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What can a passenger do if (s)he objects to the flight route? Say that after a passenger learns of or views the flight plan, she opposes it (eg due to safety). She could just refuse to board the flight and forfeit her ticket and costs, but are there less costly and dire and radical options? Despite being only a passenger, could she explain to the flight crew (plausibly via the cabin crew?) her reasons and thus request the reconsideration of the flight route? Supplementary: I elucidate that I do NOT mean for her to compel or impress a specific route (replete with all the waypoints, VORs, etc...) upon the flight crew, but only a general concern for avoidance. As an instantiation, if I were a passenger and had apprehended my flight to overfly Ukraine, even outside of the no-fly zone, then I'd remonstrate against it, in favor of a more northern one that would substantively avoid Ukraine. <Q> The passenger can in all likelihood do nothing that is going to change the route. <S> As you point out, there is always the option to not board. <S> On long range flights like this, the routing will (depending on winds aloft and other conditions) almost certainly require a fairly direct route to insure that additional fuel stops are not needed. <S> In cases where routes go over warzones or other dangerous areas, they are often rerouted, but in the case of Ukraine the conflict has until now been isolated and military in nature. <S> Either you trust the flight crew to <S> also be aware of these risks, or you don't. <S> Get on board, or not. <S> ( note: I have no idea ). <S> However, you also might be perceived as the source of the risk and detained! <A> IMO the only option is not board. <S> Passengers altering flight paths sounds suspiciously like terrorists. <S> How does the airline tell the difference? <S> Just because he looks like an Arab doesn't make him a terrorist. <S> Just because she looks like a soccer mom doesn't mean she isn't. <A> Assuming you could find a crew to listen to you, you would have to convince the captain operating the flight of your plea. <S> The captain then has to call dispatch and convince the dispatcher of the need for different routing. <S> If everyone is convinced, the dispatcher can re-dispatch you, which will probably result in a change to the ordered fuel and could result in weight restrictions due to the added weight of that fuel (and if I had to remove a passenger because of that, I know the first one I would boot...). <S> You'll also probably take a delay for the fuel people to come back out to the plane. <S> Assume this all went well, your captain got a new route filed and you are sitting back in your seat waiting to take off. <S> What you don't know however, is that many airports have preferred routing between them, and no matter what route you file between them, your clearance will always be the same. <S> So you went through all that work and now the crew is cleared back on the original routing (because dispatchers know to file these routes) and nothing has actually changed. <A> You have to remember that there is a route on the flight plan, and then there is the route the plane flies. <S> These are quite often not the same. <S> Air Traffic control can and does regularly does change routes once a plane takes off. <S> This allow ATC to control the sequence of plane to avoid congestion, reroute plane around bad weather, handle issues with weather, traffic, etc at the destination. <S> So objecting to the route based on what is planned may be an exercise in futility. <S> If you take another flight it is likely to be routed the same, or even if it is routed differently end up fly the same route. <S> There are only so many ways to get from point A to point B. <S> One way to better ensure that the flight does not fly over a certain point would be to book from point A to point C to point B. <S> But that is likely more trouble than it is worth.
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If you object to the routing, your only real option is to choose not to board the airplane. I'm sure you could raise the issue with a gate agent, and if you made enough noise or escalated it, you might be able to get a refund
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What causes aircraft to swerve during takeoff? I notice on some commercial flights that the aircraft can begin to swerve left-to-right during takeoff before we leave the ground. Sometimes this can become very exaggerated, very hard left-to-right swerving. This is typically from around mid-way through the takeoff run, becoming most severe immediately before takeoff. My first thought was perhaps it is an inconsistency in the runway from the airport I frequent but have noticed it once or twice at other airports as well, and across different carriers. However, it feels more like when driving a car and you swerve, then overcompensate the other direction and it becomes a vicious cycle. Other factors may include wind - but I've been in high-wind takeoffs before and it didn't have the same jerking motion. Any explanation to this, or am I just paranoid? *Apologies for lack of knowledge re: terminology <Q> I know you said that you don't think it's a crosswind, but honestly it most likely is. <S> As the plane speeds up and the wings start to generate more and more lift the plane is more easily affected by cross wind. <S> So, as you speed up, it gets harder and harder to keep the plane straight. <S> Throw in some gusts, and you're going to get some jerking motions as well. <S> Especially if that gust decreases the lift of the aircraft, the wheels suddenly catch the ground more and the craft is suddenly tugged harder than the pilot anticipated... <S> Here's a video of a Boeing 777 taking off in a heavy crosswind that should illustrate the point more. <A> It would be more common on turboprops as well since they have more left turning tendencies from the engines, such as torque, p-factor, etc. <S> In these airplanes the pilot has to compensate by holding right rudder, and sometimes they end up swerving a little bit as they try to find the right balance. <S> In any case, the swerving is not nearly as bad as it feels, the farther to the back <S> you are the more <S> you're going to feel it as well. <A> I am not an expert, but it could be because the main Yaw control moves from the nose wheel to the rudder. <S> During slow flight, you need to be more forceful on the rudder as there is not much control.
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Crosswind can cause it, especially if there are gusts involved.
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What's the point in escorting a threatened flight with two fighter jets? Two days ago I read in the news : Two U.S. fighter jets escorted a Canada-to-Panama flight back to Toronto after a passenger allegedly threatened the plane Friday morning. The nature of the threat or why the passenger was agitated were not specified. CBS News reported that the passenger told a flight attendant, "I have a bomb and I will blow up Canada." What's the point of escorting the flight while it has been threatened by a passenger? How do they help to eliminate the threat? <Q> Fighter jets escorting planes after various sorts of emergencies seems to be standard procedure in many countries, you hear about it quite frequently. <S> It's sometimes implied in the media that if the situation would turn into a 9/11-type hijacking it might be necessary to shoot the plane down <S> but nobody seems willing to fully clarify who could take such a decision and under what conditions on the record. <S> Now, in most cases, there isn't even a suggestion that a hijacking is happening <S> but it's difficult to determine that in a timely manner and there are still two things fighters can do in other cases: Get a visual confirmation of the situation aboard the plane (Is the plane damaged? <S> The cockpit windows obscured? <S> Who is in the cockpit?) <S> “Guide” a pilot who has lost communication to an airport. <S> Also, one factor is that being able to scramble jets is often seen as a basic requirement to assert sovereignty (witness the mini-controversy in Switzerland when it was revealed that the air force could not do it at certain times of the day) so politically it seems difficult to entirely give up on it, even if it could be argued that it's a waste of money for smaller countries to maintain an air force that does very little beside this type of missions. <A> Especially post-911 it became paramount to ensure that such aircraft form no threat to cities and other places where crashing an aircraft into them would cause serious damage. <S> Blowing it out of the sky, however bad it would be for the passengers (not to mention the psychological impact on the fighter crews and their controllers) would be preferable to having thousands of victims on the ground (and a major PR coup for some terrorist group). <S> So jet fighters are scrambled to escort the aircraft until it's on the ground somewhere or the threat otherwise neutralised (say the attempted hijacking foiled by people on board). <S> This is little different from fighters being scrambled to escort intruders into a nation's airspace (and in extreme cases shoot them down) which has been done since the end of WW2 and maybe sporadically before (without radar to detect intruders and guide interceptors <S> it's a lot harder to do so obviously, and prior to WW2 that wasn't available). <S> In this specific case it may have been overreaction to a madman with a fake bomb, but not knowing whether the threat was real or not it's easier to send up the fighters and later recall them than to have to explain to congress and even worse the press why you didn't act after the jetliner crashes into some city center during lunch hour... <S> Be happy that they have the option to send up fighters and don't have to rely on guided missiles alone, as there's no recalling those once launched... <A> In addition to @Relaxed's answer, one additional reason would be if the hijacker gets control of the cockpit and turns off the transponder. <S> ATC works on secondary radar with a signal bounced back from the plane in order for ATC to track the aircraft. <S> If the transponder is turned off, it would be very difficult for ATC to track the exact whereabouts of the plane. <S> By having escort planes, they could maintain positioning of the endangered aircraft. <A> Given the threat of "I have a bomb <S> and I will blow up Canada <S> " the cabin crew are clearly overreacting. <S> Highly unlikely a bomb big enough to take out Canada would go unnoticed, esp. <S> as the plane would be grossly overweight with it. <A> The utility of sending fighter jets is to destroy the plane before an hypothetical attempt. <S> It's unfortunate, but the point is to kill a few people to save many. <S> This can also possibly have the impact of scaring the hijacker/terrorist. <S> In the mean time, someone in the ATC can attempt to negotiate with the terrorist before any shoot-downs are needed. <S> In France, we send two fighter jets, because one jet is there to make contact with the pilot (seated on the left of the cockpit) while the other fighter stays behind the aircraft ready fire if needed. <S> The only person allowed to make the decision to fire, is the Prime Minister. <S> In fact, fighter jets take off on these missions quite often, but it's usually only for providing assistance (e.g. providing landing clearance to an aircraft with dead radio). <A> In addition to the reasons above (911-ish & transponder out), it is also an indication that somebody on the ground is aware and cares if communications are cut off and passengers do not know what is going on. <S> They may not be able to do anything and passengers may realize that, but at least you know the ground is aware and you aren't alone. <S> As far as an on board nut-job being aware of any possible "trouble" he/she may get into, I think they usually don't care if they are 911 fodder. <S> When I heard that a second plane hit on 911, on the way to work, I knew life (mostly @ airports) had changed right then.
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If absolutely necessary the plane can be prevented from making a mess of a major city, but it is basically a rather obvious visible sign to anyone misbehaving in the plane that they are in very, very deep trouble.
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During takeoff, why throttle forward then raise hand from throttle to push a button, instead of pushing button then throttling? Preface: The comments assert the video to have been horizontally flipped, probably because (I am divining) the original belonged to someone else (user 'Jb380' if I remember)? At 4 mins 3 secs of this video , the captain (who appears in the video on the right, but per the preface above, should be on the left) pushes forward the throttle, but from which he then removes his hand to use this same hand to push a button that changes an instrument display, from showing the tail view (camera) of the aircraft (to assist with taxiing???), to the primary flight display . Afterward he replaces this hand back atop the throttle. Why doesn't he instead push the button before deciding to takeoff and set takeoff thrust: this is safer than the above? For example, if abortion is decided exactly when nobody's hand is handling the throttle, then previous seconds needed to stop would be wasted? <Q> Actually he does push the button before selecting takeoff thrust. <S> Often 1 the procedure on jets during take-off is to move the thrust levers about half way, wait for the engines to spool up and only then select TO/GA or Flex thrust as desired. <S> In the video the pilot switches the display during this intermediate step. <S> So the engines are not even spooled up yet and the aircraft is still moving slow. <S> Plenty of time to stop if anything fails. <S> In fact even when nearing v₁ the reaction does not need to be that fast. <S> The calculation of v₁ includes 2 s reaction time and correct response is more important. <S> Look e.g. on this training video <S> (it's A330, not A380, but the procedure is the same). <S> The reaction is not that fast; they only retard the throttle after checking and calling the fault ("engine fire"). <S> 1 <S> It used to be that the engines could flame out if you added fuel too quickly, but that's no longer the case now when engines are managed by FADEC (full authority digital engine computer). <S> Some manufacturers/airlines/pilots maintain the procedure, most likely to avoid applying full power if one of the engines manifests some problem early. <S> Or at least the pilot in this video does it. <A> Hands off at V1 (Engine failure recognition speed) is perfectly proper in an aircraft with multiple engines. <S> The throttles still moves , however the power setting (EPR) is in the computer and the precise setting of the engines is automated. <S> The Pilot Flying the aircraft will still feel the throttles vibrating under his hand, but it's the auto throttle doing it, and not the flight engineer. <S> If Auto thrust is engaged, then there are 3 detents - Climb, Max Continuous/Flex and TOGA. <S> If Autothrust is not engaged (at any time in the flight) then the thrust levers work just like the T/Ls on any other aircraft. <S> During take off, the T/Ls are placed either in TOGA <S> (Take Off/Go Around) if the pilot is doing a max power T/O, or in Flex/Max Continuous detent if the pilot is doing a Flex power T/O. <S> When the levers are in either of these detents the FADEC (Full authority digital engine control) will give the aircraft <S> the max power available for that selection (It depends on the ambient conditions). <S> When the aircraft reach the Thrust Reduction altitude the pilot may choose to move the levers backwards to the Climb detent, and will then get Climb power. <S> The levers remain in this detent until the pilot reduces thrust to idle in the flare during the landing . <S> This means that the FADEC will give the aircraft whatever power is necessary to achieve what you are trying to do - climb power for the climb, or whatever thrust is necessary to achieve your cruising Mach number, or desired rate of descent or whatever. <S> If an engine fails, then the levers on the remaining engines are moved back into the Flex/Max Continuous detent, and the aircraft will get Max Continuous power. <S> If the pilot has to do a go-around at the destination, the pilot puts the levers into the TOGA detent and the aircraft will get all the power available. <A> Large engines, such as the ones on the A380 in the video, take time to accelerate. <S> What the pilot in the video does is apply a small amount of power to ensure correct and balanced spool up of the engines. <S> This prevents an uneven application of takeoff thrust i.e. if one or more engines are slow to spool on one side. <S> This procedure will likely be detailed in the standard operating procedures of the airline, on the aircraft I fly we advance to 1.15 EPR prior to selecting takeoff thrust. <S> He moves his hand to start his stopwatch (the Chrono button on the Airbus), this is to keep track of the amount of time the engines stay at takeoff thrust. <S> This is important to monitor as, for instance, during an engine failure you may need that power to clear terrain and your climb will be slower - <S> you don't want to damage your remaining engine(s) by maintaining a high thrust level for too long. <S> On the RB211 we have a limit of 10 to 15 minutes depending on the aircraft variant. <S> He doesn't push the button before moving the thrust levers to ensure max available time at takeoff thrust.
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This is completely normal in Aircrafts like the A380 , Boieing 777 etc .
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How are anti-aircraft missiles tested? How are anti-aircraft missiles and counter-measures tested? When they design an anti-aircraft missile, how do they test it so that it actually locks on to a target and destroys it? Do they simply fly a plane in the air and then fire a missile at it and have the pilot eject? Similarily, how are counter-measures tested? Do they fire a missile at a target and check whether it misses? <Q> These tests are still extremely expensive, into the millions per aircraft destroyed, so there are many dry runs and non-destructive tests completed beforehand. <S> Sacrificing a target drone isn't done until the project team is very confident of a positive result or they are unable to obtain necessary data by other means. <A> A large part of the complexity of any missile is in propulsion and guidance. <S> The warhead isn't trivial, but in comparison that's not the hardest part. <S> This means that in testing, you can often replace the warhead with a sensor package. <S> This applies both to missile development and counter-missile development. <S> Missile warheads additionally can be tested on test stands, without being launched first. <S> This just leaves an integration test where missile and warhead are tested in combination, and for that Brian's answer applies. <A> They also conduct many tests using towed dummy units. <S> (TDUs) <S> These will often be small in physical size but have radar reflection or heat generation to allow it to look like a normal aircraft to the missile. <S> Much less expensive to destroy. <S> The missile will also have a failsafe using the IFF technology so that it does not attack the towing aircraft, and an additional failsafe that the missile can be destroyed manually. <A> I begin with the premise that there are generally 3 different types of anti-aircraft missile systems. <S> These are (a) Man-Portable Air-Defense System (MANPADS) also called Very Short Range Air Defense Systems(VSHORADS) for example RBS-70 , Verba , Starstreak , (b) Ground based Medium-Range Surface-to-air missile systems for example <S> BUK-3 and (c) <S> Long <S> Range Air Defense Systems for example <S> Patriot MIM-104 and S-300V. <S> Now , the testing of these 3 different types are obviously different , however the cornerstone of these tests regardless of the type would include : (a) <S> Digital Simulation of launches - almost a million launches are simulated ; <S> (b) Hardware-in-the-loop simulations – thousands of tests for each system with actual missile seekers and jammers(c) <S> Flight Tests simulation (d) <S> Functional configuration audit to verify compliance with system functional requirements(e) <S> Live Fire tests - carried out on unmanned aerial vehicles that serves as targets <S> https://sites.google.com/site/samsimulator1972/home <S> There are generally 3 main parts in a missile . <S> (1) <S> The rear section contains electronic packages , a battery and the rudder mechanism (2) <S> The central section contains the sustained motor and wings (3) <S> The forward section contains electronic packages , the gyro and warhead <S> Therefore , Tests have to be conducted at the component, subsystem, or system level as well . <S> Missile Sub sections Countermeasures for air defense systems are categorized into active and passive systems. <S> (1) <S> Active countermeasures are for example flares and directed infrared countermeasures ( <S> DIRCM) (2) Passive countermeasures include infrared signature reduction, fuel tank inerting and redundant controls <S> Tests are carried out for Flares , Chaffs and Infrared . <S> The chaff cuts are tested for optimization so as to provide a broadband radar return . <S> The various tests carried out on Chaffs are related to their Performance Requirements shown in the image below <S> A Flare consists of (1) a firing cap, (2) a powder charge wadding between the charge and the bullet, and (3) a wad at the end that keeps everything in place. <S> The electrical firing “cap” creates a gas that ejects the plastic or nylon slider, 2 felt spacers that hold everything in place, and the end cap. <S> All these 3 components have to be tested . <S> For evaluation of effectiveness against two-color systems, an integrated color ratio filter system is used to enable flares and target representation to contain the appropriate amount of energy in each spectral region of interest .
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The short answer is that the final qualification tests are done against drones like the QF-4 , which are converted from retired F-4 fighters.
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What are the differences between Bearing vs Course vs Direction vs Heading vs Track? This answer from English.SE does not focus on aviation, and does not explain 'Track'. In basic, simple English, would you please compare and contrast all 5 terms in my question's title? The differences between 'course' vs 'heading' was generously explained in this answer . <Q> This is how I explain it, hopefully it helps more than hinders! <S> Track: This is my ACTUAL path traveled over ground - just like a set of tracks I would leave behind in the snow or sand, relative to North Bearing: This is the angle between the location of an object, machine or destination and either: - my heading. <S> This is called 'Relative Bearing'. <S> - or magnetic north (direction toward the magnetic north pole). <S> This is called 'Magnetic Bearing'. <S> So from the picture, if I take off from Springfield enroute to Shelbyville. <S> My course (the intended path) is due East, or 090 degrees. <S> I notice my winds are Southerly (from 183 degrees / to 003 degrees), so I make my heading 095 degrees to compensate for wind drift (or 5 degrees crab into the wind). <S> If my calculations are bang on, my track should be the same as my course , however I misjudged the winds, finding out my resulting track over the ground is 081 degrees - I must correct (by increasing) <S> my heading to get back on course . <S> Now with some airports, the navaids (NDB or VOR) are not directly at the airfield but some distance away, so if I wanted to either fly directly to the NDB or figure out my position in space during enroute nav checks, I would take the bearing to the NDB/VOR either relative to my heading or relative to magnetic north to find its position. <S> Hope <S> this helps. <A> I will try to explain as simple as possible, though I'm not a professional. <S> Heading <S> It is the value the compass shows you while you fly your plane, relative to Earth's magnetic field. <S> But your heading is not where exactly your plane goes. <S> Why? <S> because in most of the cases (if not all) there is wind. <S> Track <S> This is the aircraft's actual "path" over the ground when wind effect is "added up" to the aircraft's velocity. <S> You need track for navigation since this is where you actually go. <S> Bearing <S> If it is from north (true or magnetic) <S> : <S> Having two locations A and B, bearing of B to A is the angle measured clockwise from north to B having as angle vertex location A. <S> If it is relative: <S> Having 2 locations A and B, bearing of B to A is the angle measured clockwise from point A forward direction to B having as angle vertex location <S> A. <S> In the following picture, red is true bearing, blue is relative bearing. <S> Course <S> This is the one and only path you can follow to reach one specific point. <S> Suppose that you are instructed to "approach the XYZ point from the east" that means course 270 to the XYZ point. <S> The following pictures depicts the concept: 270 course to XYZ is the green one. <S> The red one goes to XYZ but it is not 270, the orange is 270 but doesn't end to XYZ. <S> For more information: Wind triangle <S> Aircraft heading Bearing <A> The difference between track and heading not only includes wind, but also includes flight in sideslip due to asymmetric drag (eg engine out) or pilot induced steady heading sideslip. <S> It also includes AoA during a turn; extreme case of 90degrees AoB at high AoA.
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Heading: This is where my nose points - and seeing as my nose is attached to my head, this is where my head (and thus my machine) is pointing relative to North. Course: This is my INTENDED path of travel that I have calculated taking into consideration winds, variation and declination.
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What is the minimum turning radius of an SR-71? What is the minimum turning radius of an SR-71 at Mach 3.2 and an altitude of 80,000 feet? I have heard that if an SR-71 were to cross the Pacific coast over San Francisco and pull a hard turn to the right, it would return over Seattle. I'm interested in real-world performance, taking into account things like inlet unstart (failure to capture the engine inlet shockwave in the intake) from too sharp an angle of attack. <Q> The Turn Radius of the SR-71 would depend on its speed. <S> The faster it went <S> the wider its turn radius was. <S> It was not an airframe limitation but a matter of wing area. <S> At 80,000ft, the air is too thin and the wings too small to allow for much lift to turn with. <S> At a turn radius of 80 NM, the SR-71 would cover about 145 miles, taking about 4 minutes in the process of making a 180 degree turn. <S> Details are provided in the SR-71 flight manual handbook , which is now declassified: <A> Please use the equations of this answer . <S> The numbers might be different, but the physics are the same. <S> EDIT: <S> Thanks to D_S for providing the link to the manual. <S> When flown with the maximum allowable load factor of 1.5 g at 80.000 ft (48° bank), the turn radius at Mach 3.2 (equivalent to v = 953.3 m/s in 80.000 ft) will be 83.5 km. <S> To be more precise, you will need to add the effects of earth rotation, but for now I leave this away. <S> As you can see, the turn will still need 163 km or 103.7 miles, but not the distance from San Francisco to Seattle which is more than 6 times bigger. <S> To turn this around: A circle at Mach 3.2 which has a diameter of 1092 km requires a bank angle of 9.6°. <S> That can hardly be called a turn. <A> Considering the current flight status of the SR-71 (retired) <S> it's maximum speed will depend on the tug moving it <S> and the turn radius is probably around 30-40 meters depending on how far the nosewheel pivots.
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The SR-71 had a minimum turning radius at altitude of about 80 nautical miles (NM) .
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My windsock is erect, what does this mean? I know that airport windsocks are calibrated to reach full erection at a particular wind velocity. At half that speed, the first half of the windsock should be erect and the second half should droop sorrowfully. At one third the speed it will be one third, and so on. Trouble is that not all windsocks are calibrated the same way. How do I find out what wind velocity will bring my airport windsock to a fully erect state? <Q> Windsocks come in various sizes and speeds, but an FAA Standard Wind Sock aligns with the wind at 3 knots, and is fully extended at 15 knots like CGCampbell pointed out . <S> A typical wind sock (at least around here) looks something like this: <S> The stripes are actually useful: The first stripe indicates a 3-knot breeze (The wind sock has turned and aligned with the wind - usually you should look for an anemometer near the wind sock to determine if there's any appreciable wind because often the first segment is held open by the frame.) <S> The second stripe is ~ 6 knots <S> The third stripe is ~ 9 knots <S> The fourth stripe is ~ 12 knots <S> The last stripe is 15 knots or higher If the windsock is missing you probably shouldn't be at the airport. <S> If the pole is missing you're probably on your way to Oz. <S> (You can actually get a far more precise estimation if you're willing to do some trigonometry, but this works well enough for most purposes.) <A> According to the FAA, Advisory Circular 150/5345-27E , dtd 26 Sep 2013, Paragraph 3.2.2, 3.2.2 Dimensions The taper or the fabric windsock from the throat to the trailing end must be designed to cause the windsock to fully extend when exposed to a wind of 15 knots (28 km/hr or 17 mph). <S> The paragraph, 4.2.6 Windsock Extension gives the variance of wind speed allowed which should still cause a full extension of the wind sock, but that paragraph appears to need editing to put in the starting values for mph and km/hr, 17 and 28 respectively, which are indicated above. <S> 4.2.6 Windsock Extension. <S> Test the windsock to assure that it extends fully when subjected to a wind of 15 (+2,-1) knots (+3.7,-1.8) km/hr or (+2.3,-1.2 mph) ). <S> So, for instance, the sock should be fully extended from 15.8 mph through 19.3 mph. <A> The main function of the windsock is to show from which direction the wind blows. <S> The faster the wind blows, the straighter and more horizontally the wind extends. <S> A 3-knot (5.6 km/h; 3.5 mph) breeze will cause the properly functioning windsock to orient itself according to the wind. <S> If the windsock has blown away, the wind is greater than the 75 knot design limit. <S> http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5345_27e.pdf <S> Windsocks are accurate only within a small radius . <S> In those airports where there is only one windsock and it's alongside the midpoint of the runway, the only thing of which you can be certain , is that, the wind at either end of the runway will NOT necessarily match. <S> This explains why many airports have windsocks at both ends of the runway. <S> The sock in the middle tells traffic which runway to use, but the windsock at the end of the runway tells the pilot what to expect on approach. <S> Note that the correspondence between wind speed and degree of extension and straightening will varies from one model to another. <S> You can calibrate the windsock with the help of a anemometer. <S> After installing the windsock on the ground , use the anemometer to calibrate the shape and orientation of the windsock to specific wind speeds. <S> The anemometer (wind meter) should be held at the same height as the windsock’s larger opening . <S> Point it into the wind and <S> record the wind speed reading. <A> Myth alert! <S> There is a somewhat widespread belief in the most accepted answer here. <S> It is not true that there is a 3kt relationship per segment of the windsock. <S> Those who claim so provide diagrams of this but never photographs. <S> Also the FAA does not specify this in their specification for windsocks. <S> Windsocks are designed to fly straight, it is the angle of the dangle which indicates windspeed. <S> The first segment (the one nearest the mast) is often rigid so as to keep the rest of the windsock from entangling itself around the mast. <S> But other than that first rigid section you will not see a bent windsock. <S> FAA spec: http://www.faa.gov/documentLibrary/media/advisory_circular/150-5345-27D/150_5345_27d.pdf
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As per FAA standards a 15-knot (28 km/h; 17 mph) wind will fully extend the properly functioning windsock.
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Is it possible to use thrust reversers to taxi backwards? Can commercial airliners theoretically taxi backwards using reverse thrust? If this is possible, why isn't it common? I can already imagine some safety reasons... <Q> This is called Powerback , most aircraft can do it, but it is not done very often. <S> In a jet aircraft, the three main problems are: Reverse thrust tends to throw a lot of debris into the air because the exhaust is deflected to the sides and up and down too. <S> This debris can damage the engine itself, other things on and around the aircraft or injure someone on the ramp. <S> It is less of a problem for aircraft with tail-mounted engines (so DC-9s often used powerback), but that engine configuration is not used as much any more in transport aircraft, as it is less aerodynamically efficient. <S> A related problem is that the compressor might suck in its own hot exhaust gases. <S> This might lead to temperature-induced damages in the last (high-pressure) stages of the compressor and health issues for passengers, since the air conditioning system works with bleed air from the compressor. <S> Reverse thrust is rather inefficient on jet engines, so it uses a lot of fuel. <S> As Casey mentioned in the comment below , the pilot has to be careful using the brakes during powerback: the main wheels are very close behind the centre of gravity, so harder braking can lift the nose wheel, causing the pilot to lose control and even causing damage to the tail if it hits the ground (“tail-tipping”). <S> So a tug is both cheaper and safer. <S> But a tug is still preferred because transport aircraft don't have any rear visibility, so the pilots can't see where they are taxiing. <S> With tug the driver can see behind the aircraft, and a ground marshaller walks along side each wingtip with an intercom connected to the plane. <S> Lastly, since aircraft are able to turn almost on the spot using differential braking and thrust and 180-degree nosewheel steering, at airports with few facilities there is generally enough space around the aircraft to permit the pilot to reverse out easily. <A> It can be done, in fact the DC-9 and MD-80 aircraft are approved for backing up using reverse thrust. <S> It is called "powerback". <S> It is rarely used since it is quite fuel consuming, noisy and increases the risk of sucking up debris near the gate area causing damage to the engines. <S> Here's a video of an MD-80 backing up. <A> Can commercial airliners theoretically taxi backwards using reverse thrust? <S> - <S> After an airshow at RNAS Yeovilton, Somerset in the 1980s <S> a British Airways Concorde found it could not taxi out for departure as it had been parked too close to an adjacent hangar (and didn't have the required turning circle)... there was no suitable towing gear on site, or within easy reach... <S> so after a discussion with his engineers the pilot decided to reverse taxi a short distance using reverse thrust.... <S> the centre of gravity was adjusted by transfering fuel to the forward fuel tanks, fingers were crossed, and... it worked! <S> (I was there to see it, working in the control tower)
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In propeller aircraft, reverse is more efficient and does not throw up as much debris, so it is sometimes used.
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Why do multiple planes arrive from the same airport at the same time? I'm looking at the Arriving flights page of the Vancouver Airport and in many cases there are several planes coming from the same airport, arriving at the same time, all at the same gate. Does it count for only one plane and they are affiliated companies? Here are some screenshots: <Q> Two or more airlines can agree to share the same route and operate it with only one aircraft to reduce cost of operation. <S> See the WikiPedia article on codeshare <S> Here an excerpt: <S> A codeshare agreement, sometimes simply codeshare, is an aviation business arrangement where two or more airlines share the same flight. <S> A seat can be purchased on one airline but is actually operated by a cooperating airline under a different flight number or code <S> In the case where multiple flights are listed arriving at the same time from the same departure airports, there will only be one physical airplane serving the connection but under different flight numbers and operators. <S> The different flight numbers and operators are listed to make it easier for passengers to identify their flight if codeshares are being used. <S> On busy airports or where there is not enough space on the information displays to show all flights of a codeshare, the relation is only shown once with rotating flight numbers. <A> As others have already said, those are codeshare flights. <S> Just to clarify, this means that there is only one physical plane flying this route at this particular time <S> but it has several flight numbers for marketing reasons <S> (it can also make a difference for things like frequent flyer miles, etc.) <S> Often, a three-digit flight number means the relevant airline is the “real” (or “operating”) carrier, whereas longer numbers are used by “virtual” (or “marketing”) carriers. <S> Thus the first flight in your list would actually be operated by Lufthansa, the next one by Virgin Atlantic, etc. <S> There are several entries on the arrival and departure list because different passengers will expect a different airline name and flight number (the codes like LH492 or AC9101) and need to be able to find it in the list. <S> In some airports, there is only one line on the video displays in the terminal, with the flight number rotating every 30 seconds or so. <A> As SentryRaven correctly answered, they are codeshares. <S> So to be able to offer better choice of connections, multiple airlines agree to sell tickets on the same flight and the flight then gets a separate number from each of them. <S> It is especially common on short flights.
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The reason is mainly that passengers want to buy tickets for the whole trip from a single company, because it is easier and because it makes it clear responsibility of that airline to rebook them on another flight if they miss a connection due to delay of previous flight. This has to do with codesharing or codeshare .
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Can small children be seated away from their parents/guardians on a flight? I am interested if there is any law or regulation which prohibits carriers from seating children in a seat not adjacent to their parent/guardian? I am flying with a group of 17, which includes 2 infants (without allocated seats), but seven children ranging in age from 2-5. We opted not to pay the extra charge to pre-allocate seats, and the airline has allocated us seats spread around the aircraft in a configuration which does not allow an accompanying adult to sit next to a child. I was sure there was some air law which prohibited this on safety grounds, but have been unable to find it. This question relates to the EU, but answers regarding other jurisdictions welcome. <Q> This is what I could find. <S> I looked on the Civil Aviation Authority's website and found this article. <S> Seating Allocation <S> Families, children and infants <S> Young children and infants who are accompanied by adults, should ideally be seated in the same seat row as the adult. <S> Children and accompanying adults should not be separated by more than one aisle. <S> Where this is not possible, children should be separated by no more than one seat row from accompanying adults. <S> This is because the speed of an emergency evacuation may be affected by adults trying to reach their children. <S> Whenever a number of infants and children are travelling together the airline should make every effort to ensure that they can be readily supervised by the responsible accompanying adults. <S> If there was a law then Ryanair would have been in serious trouble for charging people extra money to sit next to their kids. <S> Ryannair booking separates mum and tot <A> I don't think there a "law", but the flight staff would prefer that. <S> When my children were young, they sometimes ended up separated from us. <S> Usually they were just a row or two away from us. <S> On several occasions the cabin personnel arrange with kind passengers to switch seats so my two children could at least be seated together. <A> Although there is not a rule about that, but since you are in a large group with many children, you may call the airline directly to see if they can make a special seat arrangement. <S> Usually, they would do so.
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The seating of children close by their parents or guardians should be the aim of airline seat allocation procedures for family groups and large parties of children. From what I read, it doesn't look like there is a law set in stone, but instead it is recommended by the CAA to be put in regular practice by airlines.
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Can I fly "into" the Grand Canyon? I haven't looked at the Grand Canyon on a sectional yet, but I know that it is definitely big enough (by far) so that someone could fly a plane under the level of the rim and stil meet all of clearance requirements for VFR flight. Is it legal, and safe to take an airplane into the canyon? <Q> If you look at the sectional chart, you see this notice: Searching through the CFR (Title 14, Part 91) brings up this Special Federal Aviation Regulation No. 50-2 - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ. <S> Ther is also Supbart U of Part 93. <S> The Subpart U regulations seem to be the most current applicable regulations (please correct me if I am wrong). <S> The rule applies to everything under 18,000 feet MSL within an area around the park (like the chart says). <S> Except in an emergency or if otherwise necessary for safety of flight, or unless otherwise authorized by the Flight Standards District Office for a purpose listed in 93.309, no person may operate an aircraft in the Special Flight Rules Area within the following flight-free zones: <S> It then describes the four zones: <S> Desert View, Bright Angel, Toroweap/Shinumo, Sanup Flight-free Zone. <S> You can't fly through these, but between them are "corridors" in which you are allowed to fly above a certain altitude. <S> See this map for locations of the Flight-Free Zones and corridors. <S> There are also minimum sector altitudes for different areas, including the corridors, which are going to be the main thing preventing you from flying very low. <S> The altitudes are different for commercial air tours versus transient and general aviation. <S> Also: no person may operate an aircraft within 500 feet of any terrain or structure located between the north and south rims of the Grand Canyon. <S> There are also noise limits depending on the aircraft type. <S> For some info on the background of these rules, see this NPS study . <A> It is generally not legal to fly into the Grand Canyon - there is a SFRA (Special Flight Rules Area) over much of the canyon which is designed to keep General Aviation traffic from annoying tourists (and away from the commercial air tour operators). <S> For both GA and commercial tours there are altitude restrictions which keep flights well above the canyon rim. <S> ( You can download a chart of the Grand Canyon SFRA from the FAA ) <S> Were it legal <S> it probably would not be the safest idea anyway: <S> Inside the canyon there are strong, often unpredictable winds. <S> The conditions would be similar to flying a mountain pass, but with substantially less clearance between your wings and the canyon wall in some places. <A> Safe maybe, but not legal. <S> Not anymore - the helicopter tours did fly into the canyon years ago, but it became illegal in 1987, prompted by a mid-air collision in 1986. <S> A Special Federal Aviation Regulations (SFAR) was adopted which regulates traffic below 14,500 ft MSL. <S> This height limit can be raised seasonally to 18.000 ft, and only commercial tour operators are allowed to fly below. <S> For GA traffic three small north-south lanes allow crossing at 10,500 (southbound) rsp. <S> 11,500 ft (northbound). <S> Now even the number of fixed wing and helicopter tour flights is restricted to reduce noise.
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The answer is: no, normal flights are not allowed under the canyon rim.
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How is fuel dumping safe? The answers to this this question make it clear how modern airliners dump fuel in the case of an emergency. As far as I understand, fuel dumping might be done to lower an aircraft's weight to the maximum landing weight, particularly soon after takeoff. As far as I understand, jet fuel is typically not safe. When I, as a complete outsider, hear of fuel dumping, I imagine a whole bunch of dangerous corrosive fuel being dropped on whatever happens to be below, and it sounds like a frankly awful idea. What makes fuel dumping safe, or if it is dangerous what makes it worth it? <Q> Fuel dumping is almost always an emergency maneuver, and it is never good for the environment. <S> So the alleged danger from the dumping must be balanced with the imminent danger to the 200–400 passengers involved. <S> It is never an easy decision <S> but that's why the Captain gets paid the big bucks... <S> It is not going to explode. <S> Jet-A can be compared to kerosene <S> and I don't have that statistic <S> so let's compare it to Diesel Fuel which is not dissimilar to Jet-A. Diesel Fuel at 400°F(204°C) <S> is as volatile as gasoline is at 70°F(21°C). <S> Obviously that is a big difference. <S> Jet-A also evaporates into the air, so little if any hits the ground. <S> The biggest danger I see is to the atmosphere. <A> It's not really safe in an environmental sense, but it's not that bad. <S> Jet fuel is essentially kerosene, which is harmful, but as far as engine/industrial fluids go, it's pretty benign. <S> Additionally, when an airplane dumps it, it's diluted so much by the time it makes it anywhere that it's not a significant concern anymore. <S> On the flip side, if an airplane didn't dump fuel and landed overweight, the potential side effects could be disastrous and could result in many injuries and damages. <S> Basically, it's choosing between two bad options, landing overweight or dumping fuel, and dumping fuel is the least bad of the two of them. <S> In any case, it's quite a rare occurrence. <S> You are exposed to far more toxins just walking down the street of a city than from airplanes dumping fuel. <A> Up-voting @skipmiller <S> , I offer this addendum if it is dangerous what makes it worth it? <S> Emergency Landing <S> After Takeoff Large aircraft typically cannot land as heavily as they can take off. <S> It's a structural issue. <S> So fuel dumping would be done if an emergency did not allow the time to burn down to allowable landing weight. <S> Maintain Flight with Engine/Power Loss <S> If available power did not allow sustained flight one might dump fuel. <S> Worse if you were over mountains and needed to stay high. <S> Ditching <S> There was a case of a C-130 - a high wing plane - ditching in the Atlantic. <S> It floated for a couple days with empty gas tanks and had to be shelled to force it to sink. <S> Fuel Leak <S> If a wing tank fuel leak was causing aircraft balance problems one might dump from the opposite wing to keep the aircraft controllable. <S> Life Imitating Fiction <S> 15 minutes after takeoff we lost all thrust on 3 engines. <S> Our gross weight forced us into a controlled descent. <S> Dumping most of our fuel might very well have kept us airborne on 1 engine, if not I think empty tanks would have limited possible fuel fire in the controlled crash. <S> I was about to dump 45,000 lbs of JP-4 all over west Texas when we solved our engine problem. <A> Fuel dumping is done by many types of Aircraft(fighter etc.) <S> it is not limited to the role(cargo, passenger etc.). <S> Although the purpose may be same.(Sometimes its done to reduce the load, to avoid any accident). <S> In a fighter plane fuel is dumped to reduce the weight and increase the distance to cover(the weapons it carries already has tons of weight on the plane). <S> This could be the same in passenger but situations may vary. <S> Fuel dumping is really a serious threat to the environment or the biological impact especially if it's dumped in the water(causes damage to maritime species and irreversible damage to the coral reefs if present).
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Dumping fuel sounds dangerous but it is not.
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How can the CVR from a Cessna 560XL only contain old records and none from the fatal accident? Is it possible that the CVR from a Cessna 560XL is just showing old records and nothing from the fatal accident when the plane crashed? I´m talking about the airplane crash in Brazil, where a election candidate was killed . The investigation team said that the data in the CVR contained only old data and they could not pinpoint from when those recordings were. <Q> <A> The FDR and CVR are not magical, they can fail. <S> So can the components of the aircraft that feed them data. <S> E.g. if there were something wrong with the microphones in the cockpit, the CVR would not record anything being said there. <S> At most it'd record static. <S> Same if there were a fault in the data cable feeding the data to the recorder (I assume most of those circuits are at least dual redundant, but at some point it all comes together in a single plug). <S> If the CVR isn't properly connected to the aircraft, it won't record anything. <S> This can happen, and it doesn't have to be some malignant act. <S> A simple error in a maintenance procedure can do it. <S> It wouldn't be the first time a flight recorder holds no useful data. <S> There have been other instances where the events that eventually caused the crash themselves caused the data feed to the recorders to be interrupted some time before the crash for example. <A> Everyone Fight Data recorder(FDR) and CVR(Cockpit Voice Recorder) are both present on the Cessna 560XL; The statement made by the authorities could: Be true. <S> But for that to have happened, the airplane would have to have both Circuit Breakers(CB) pulled out by someone. <S> When pilots conduct their pre-flight checks lights would illuminate indicating the problem. <S> Or..... <S> It is indeed part of a cover up. <S> Several witnesses said they saw one engine on fire before the plane went down. <S> Having an engine fire during a go-around maneuver inside clouds is something extremely difficult and the flying pilot could have lost situation awareness and became disoriented.
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If the fuse was pulled between the previous flight and the crash then yes, the CVR can only record when it has power Pulling the fuse or going behind the panel and cutting the wire will prevent it from recording.
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How do airlines dispose of a passenger jet when it's no longer airworthy? When a plane is finally considered to not be airworthy, what happens to them? Do they take them apart bit by bit? Do they sink them offshore to make them into reefs? Are parts stripped and sold as spares? Are there legal procedures the airlines have to go through? What happens? <Q> The parts will either be removed and sold as spares, or chopped up and recycled or disposed of. <S> So a lot will depend on how easy it is to remove the part, and how much of a market there is for it. <S> Airplanes are disassembled to a large extent during heavy checks, which can provide an opportunity for substituting in spares. <S> Engines: Probably the most valuable part of the airplane. <S> These will be removed and either used as whole spares or for spare parts, depending on the condition and how many of the type are still in service. <S> Cockpit instruments: <S> These will be removed and used as spares as well, if there is enough of a market (everyone wants those fancy glass cockpits these days). <S> Interiors: <S> These may be removed as well <S> , they can be used as spares. <S> Control surfaces: <S> These can be removed and used as spares as well. <S> Windows: <S> These can be removed and reused. <S> Systems: <S> Pumps, electronics, lights, actuators, etc. <S> : Most of these can be removed and sold as spares. <S> Landing gear: <S> This can also be removed and reused, depending on the number of cycles it already has. <S> Tires: <S> The tires may be reused if not worn out. <S> The tubes may not be reused. <S> Airframe: <S> Although some parts may be able to be used, generally the effort and the fact that there are probably many cycles on the part will prevent much from being used as-is. <S> The metal will be chopped up as scrap. <S> They are already working on recycling major composite structure as well, since manufacturing scrap is already being created. <S> According to Boeing , with modern recycling processes, the metal, plastic, wires/electronics, and carbon fiber composites are used for: 15% High-grade industrial <S> 50% Low-grade industrial 35% Landfill <S> As it often is with business charts, it's not clear if these are by weight, volume, or what. <S> This company claims to recycle 90% of the weight of an aircraft. <S> There are of course cases like Steve V. mentions where the plane is donated to some institution, but this doesn't happen to most planes. <S> There are also ways that airplane parts find other uses . <A> They send it to a professional demo team that drains the fluids, grabs the spares and cuts up the hull for the materials and send it all to be recycled as possible. <S> There are plenty of youtube videos detailing the process like https://www.youtube.com/watch?v=xDxJAO__6t8 <A> FedEx has lately been donating their 727 retired fleet to flight schools and training departments. <S> FedEx Donates Boeing 727 to Trinidad & Tobago Civil Aviation Authority <S> FedEx Donates Retired Boeing 727 <S> To Broward Aviation Dept <A> Very few end up in a career as firefighter training objects.
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Generally the planes are scrapped by a recycling company .
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How to find polar curves of airliners? The pilots operating manual of our Cessna 182 contains the lift-versus-alpha and lift-versus-drag data of the airplane, so I assume this is data that should be publicly available. Is there a trustworthy resource where I can get the polar curves of different aircraft, especially airliners? I'm looking for that of the Airbus A350 XWB in particular. <Q> Polar curves for older airliners can be found in lecture notes or technical publications. <S> The drag polars of the most recent ones, where no independent measurement is yet possible, are a closely guarded secret. <S> If you see something, it will be restricted such that an important part of the puzzle is missing. <S> For the polars to be meaningful, you need aircraft mass and flight conditions, air temperature and density and sometimes also engine thrust information to make any meaningful comparisons. <S> Also be aware that the Airbus method to determine the reference area is different from Boeing's, but at least those methods are published. <S> Full disclosure is only available to potential customers on the basis of an Non-Disclosure Agreement (NDA). <A> You may choose to download this Excel spreadsheet which contains a list of over 100 glider performance figures in the tab "Gliders" . <S> The spreadsheet allows comparison of two aircraft <S> **Polar Curves <S> *. <S> Boeing and Airbus does not make public the figures pertaining to Drag Polar Rates. <S> You can find some assumptions here . <A> I know of no source for the A350. <S> They will in all probability not be 100% accurate, but they work much better than required for your run-of-the-mill back-of-a-napkin calculation. <S> Keep in mind that for any meaningful analysis, you need a fairly accurate engine model, too, and before going into even more detail you need to be sure whether engine nacelle drag is included in the drag curve or the engine model or (worse!!) <S> in both or neither. <S> Also, if you just need some independent data to innocently play with, google "Piano X 787 sample analysis".
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I was moderately surprised to learn, however, that there are surprisingly well-modelled drag curves for many modern jet transport aircraft including the Boeing 777 in a book called Aerodynamic Design of Transport Aircraft by Obert.
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What are the major non-pilot causes of GA accidents? I'm considering getting a private pilot license. From what I've read, pilot error is the leading cause of major airline crashes -- such as on this page , but that's for major commercial carriers. As the pilot, pilot error is something that I can address myself. One of the things that concerns me is the chance for an accident due to circumstances beyond my control. What's the cause breakdown for general aviation accidents? What are the most common mechanical failures? <Q> For a statistical overview of General Aviation accidents I suggest checking out the Joseph T. Nall Report prepared by the AOPA Air Safety Institute. <S> Everything I'm citing below comes from the most recent report (the 23 rd report, covering 2011). <S> The leading causes of accidents in 2011 were: Pilot Error - About 77% <S> This includes poor flight planning, weather encounters, and a host of other things that we could at least theoretically avoid <S> if we actually did the things we were taught to do in training. <S> Mechanical or Maintenance related - About 13% <S> This includes engine failures, control system problems, landing gear failures, etc. <S> The largest chunk of mechanical failures are "powerplant failures", which account for 38% of the mechanical failures, or a bit under 5% of total accidents. <S> Everything Else - About 10% <S> This includes freak occurrences like a flight instructor "walking into a moving propeller" <S> (I kid you not, it's in the report!). <S> A large chunk of these are also engine failure for causes that could not be determined. <S> If we add all the engine/powerplant failures together (the explainable ones from "Mechanical" plus the unexplained ones from "Everything Else") they come out to be 11.5% of total accidents, and are statistically the number two cause of Non-Commercial General Aviation accidents after "Pilot Error". <A> Here is a good analysis that is a bit dated but should be relevant. <S> The data is from 1985-1995, 160,000 planes and 20,000,000 flight hours <S> Accident causes: Pilot related: 80% Mechanical/maintenance: 16% Other: 2% Unknown: 2% <S> The focus is mainly on pilot error (which is an interesting read). <S> The breakdown of the mechanical/maintenance issues is as follows: Engine <S> /Prop: 70% Gear/Brakes: 15% Oil system: <S> 5% Controls/airframe: 2% Fuel System: 3% Electrical/Ignition: <S> 3% Vacuum Sys/Instruments: 2% <S> The NTSB has a lot of data available either in reports or by database query . <S> The reports only break mechanical issues down to powerplant/non-powerplant. <S> During 2007-2009 it was about 80% powerplant, 20% non-powerplant for personal flying. <S> Other types of flying had various distributions. <S> If you consider oil and fuel as powerplant systems, then it's about the same as the data above. <S> Anecdotally, from reading through many GA accident reports where maintenance was a factor, a lot of things come up after a maintenance visit. <S> Things not attached properly/securely, not done correctly. <A> My experience as a long time pilot and mechanic <S> If the powerplant is repaired or overhauled properly according to manufacturers recommendations and all the parts are approved and within tolerance the power plant can be expected to last until TBO. <S> External components often fail much sooner than TBO. <S> Items such as exhaust baffles blocking exhaust outlet, Magneto failure, starter drive coming apart, vacuum pump attachment failure, fuel pump failure, fuel injection or carburation problem, alternator failure and the list can go on. <S> Preventive maintenance and detailed inspections can prevent failures.
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So having good maintenance, and doing a very thorough check afterwards, will help. I have seen engine failures caused by accessories or other components external to the actual internal powerplant.
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Can cabin pressure be lower than outside pressure? In order to allow adaption to changed pressure, the pressure change in an aircraft cabin is stretched out over time. My observation is that the cabin pressure drops even before the plane takes off, and has not yet reached ground level at the time the aircraft lands. This would make sense, allowing for longer adaption times, but needs better sealing which is able to work both ways. My question to the systems specialists: Can an aircraft cabin have a lower pressure than outside, and is the technique of stretching out the pressure change as explained above actually used? <Q> Besides the sealing the aircraft would also need a vacuum pump that is able to pull air out of the cabin which means extra weight. <S> The way aircraft maintain cabin pressure is through a air cycle machine that pushes air into the aircraft and outflow valves. <S> There is no facility to pull air out of the craft. <S> Any pressure drop <S> you may experience on the ground <S> is probably because the pilot increases air pressure on the ground slightly to test the seals and then releases it before takeoff. <A> The A320 family as well as the B737NG series of aircraft start to pressurize during the takeoff roll. <S> The cabin pressure is increased by about 0.1 Psi as this makes pressure changes on the outflow valve during the roll and the rotation less noticeable. <S> Only during a descent with the outflow valve closed, the cabin pressure could become lower than the ambient pressure. <S> To prevent damage due excessive under pressure aircraft are fitted with inflow valves that open automatically if the pressure differential exceeds a threshold. <A> Can an aircraft cabin have a lower pressure than outside <S> Yes, absolutely is CAN. <S> It's not desirable, but if the seals are all tight enough & you descend quickly enough, it can happen. <S> Because the effects on the structure would be bad, aircraft typically have a negative pressure relief valve to <S> prevent this from happening. <S> By definition, you don't need to prevent something that can't happen, so yes, a negative pressure differential is possible. <S> What you want to avoid, and with modern pressurization controllers, you probably can't reach, is a situation where you descend quickly enough to "catch the cabin" and the cabin altitude matches the aircraft altitude. <S> (Which is to say, you're depressurized -- with or without the negative pressure relief valve opening -- a few thousand feet above the ground.) <S> At that point (assuming you're still descending quickly), the cabin rate goes from something mild, a couple hundred feet-per-minute, to something much greater, perhaps a couple thousand feet-per-minute. <S> If you aren't used to dealing with that sort of a rate of change, it is disconcerting & uncomfortable, and for somebody who is flying with a minor head cold who could keep up with a gentle rate of change, it could be pretty painful. <S> And since nobody wants to scare Grandma, this is undesirable! <S> Thankfully, with modern pressurization controllers, you probably won't ever get there -- they'll manage the rate to keep things on schedule regardless. <S> With an older analog controller, it's possible, although probably pretty rare. <S> As explained in other answers, the modern controllers start to pressurize so that the cabin altitude goes slightly below the airport elevation (i.e. the cabin pressure rises slightly) at some point before liftoff ( <S> when throttles are first advanced, typically -- it's all automatic). <S> And on landing the cabin is likewise slightly pressurized, and that pressure bleeds off slowly after you have weight-on-wheels. <S> This is done so that the system transitions into and out of pressurization gradually, instead of immediately upon liftoff or on landing. <S> The outflow valve moving at full speed can give you a pretty good "pop," and that's not comfortable, so gradual transitions are designed in. <S> It's all about keeping the paying passengers comfortable & happy! <A> No aircraft is capable of reducing pressure below ambient - that would require pumps going the other way, and there's zero reasons to do it. <S> Your observation of the cabin pressure dropping is an illusion, probably the pressure increasing a small amount as the pressurization system comes online. <S> If it descends very quickly it could have in internal pressure of 8,000 feet (normal cruise pressure) but be below that altitude. <S> The difference would not last long, but it does take time to pump up a widebody - a fully pressurized 747 holds an extra ton of air, engines are at idle and the outflow valve (inflow in this case) isn't all that big. <A> However, as previously mentioned, it is possible to descend at a rate that results in a lower pressure inside the cabin. <S> In the T-38 <S> we will actually RAM DUMP before opening the canopies for this exact reason. <S> The pressurization schedule is such we are at ambient pressure until reaching 8000' before it begins to pressurize to stay at a cabin altitude of 8000' until 23000'.
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To my knowledge there is no aircraft that has the equipment to purposely create a lower pressure inside the cabin. It is conceivable that an aircraft could have a negative pressure differential on descent.
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How are credit cards processed during flight? If telephones/smartphones/tablets are not allowed on planes, how comes when you buy duty free items from the cabin crew and pay by cc they will use the card reader? I suppose that in order to remove credit there must be some sort of connection to the various credit cards circuits in real time in order to achieve this? <Q> Presumably, they use an off-line transaction. <S> The reason your credit card has raised numbers is that, in the old days, before ubiquitous data connections, a card transactions used a machine like this to transfer an imprint of your card details onto a form, using carbon paper. <S> You would then sign the form and the merchant would send it off to the bank to get paid. <S> It wasn't possible to verify in advance that you had enough money in your account but <S> the deal was that the bank would honour the transaction and then come after you with a big stick. <S> The point of my mentioning this is that, although we're now very used to the idea that the merchant talks to your bank while you make a card transaction, this wasn't the case even 20 years ago. <S> Today, it's still possible to make a card transaction without verifying in advance that the card has sufficient funds, so that you can still buy stuff on your card even if the merchant's phone line or internet is broken. <S> In fact, the last-case fall-back is to go back to the swipe machines and carbon paper. <A> It will either go through the airline's existing air-to-ground system (like the seat-back phones you pay $5/min for) or they've got a store-and-process-later arrangement with the card companies. <S> (Just because you can't use a phone doesn't mean the airline can't, they just follow certain conditions better) <A> What is it called? <S> Buying stuff on an airplane during flight is know is in-flight commerce (IFC) . <S> How it works? <S> Limitations <S> Because of this billing mechanism – which sometimes results in fraudulent transactions – there is a ceiling of the value of items that can be comfortably sold today. <S> Read more here and here . <A> I worked with the credit card processing at one of the bigger airlines a few years ago. <S> We used handhelds that stored the info from the magnetic strip of the card. <S> The transactions were uploaded to our back office system and then to the payment service provider after the flight landed. <S> The only "hard" protection is the modulo 10 checksum of the credit card number ( http://en.wikipedia.org/wiki/Luhn_algorithm ). <S> The fact that the airline knows exactly who is on a flight also makes it much harder to get away with this type of fraud. <S> During my time at the company I don't think I heard of a single case of attempted credit card fraud (that doesn't mean there weren't any). <S> I think theft is a much larger problem in on-board retail. <A> Transactions are offline. <S> The data is sent to the payment gateway on connection between the POS and wifi/GSM network on the ground. <S> Fraud happens, a lot. <S> Airlines have dedicated departments to chase these failed payments with varied success. <S> One Dutch airline, once the card ceiling was crossed (e.g. upgrades for a family might cost over €1000 which might be the ceiling limit set) would have the captain make a call to have the card payment cleared. <S> You're welcome,Mr J.
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Credit cards are swiped via wireless handhelds on aircraft but the transactions are processed when the aircraft gets on the ground.
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How are off-wing jet engines transported? One of the optional services in Rolls-Royce TotalCare is "Engine Transportation" This service includes routine transportation of engines between the customer’s main base (or designated station) and the engine shop, and/or remote site transportation. Jet engines can be very large heavy and expensive items. How are they transported? Are they flown or do they use road transport? Are there dedicated vehicles? <Q> They have the usual transport options: shove into cargo area, on a flatbed truck, shipping container,... <S> They can also be attached below the wing of a large aircraft and flown with if there is no room in the cargo area. <S> (stolen from this question ) <S> Notice the extra engine on the near wing. <A> The Conroy CL-44 <S> "Skymonster" was built for the purpose of transporting three Rolls-Royce RB-211 engines. <S> It was a derivative of the Canadair CL-44 and was meant to transport the engines for the Lockheed Tristar . <S> Jack Conroy had before modified old C-97s to Super Guppy transporters, and those initially transported Saturn rocket stages for NASA. <S> The picture below was shamelessly copied from the Wikipedia article. <S> Note the bulges near the tail: They cover the hinges for the sideways opening fuselage. <S> Today, Boeing 747 freighters can swallow most engines, so in the age of widebody transporters there is no more need for special aircraft for engine transport. <A> Having lived for nearly 15 years around the Boeing factories in Seattle, it was a common sight to see a flat-bed truck with a tarp-covered engine driving up and down the freeway. <S> Just like other big industrial machinery, they build a mounting for it, put it on a truck, and drive it down I-5. <A> It's apparently pretty hard to get outer engine dimensions, but based on fan size and adding a bit, all but the largest engines will go on a standard truck. <S> Oversize permits are readily available. <S> Rolls-Royce makes engines in Derby (amongst other places) but not at the airport. <S> ( East Midlands airport has one runway, 8200 feet, which is a bit tight for a 747.) <S> Therefore, engines must leave the factory by truck at least once. <S> I expect that the decision to send the dud engine for service by truck, boat, on the wing or in the hold will be purely economics. <A> It is important that the transport company uses fully air-ride trailers and advanced load securement techniques to ensure zero stress on sensitive engine components. <S> Peter Kämpf - While you are correct that some engines can fit inside of an aircraft for transport, the cost for this service is enormous when you compare it to a truck and trailer. <S> Also larger engines such as the Trent 1000 <S> (Fits on a 787 Dreamliner) will not fit inside of an air cargo carrier.
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Jet engine transportation is a highly specialized task, the primary method is ground transportation via truck and trailer.
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Why does the Boeing 737 have 5 x the passenger fatalities of the Airbus 320? I thought I'd compare the accident rates of these two similar, competing, very successful aircraft. 737 A320Introduced 1968 1988Number Built 8104 6171Accidents/Incidents 329 60Hull Loss Accidents 154 23Fatalities 4287 782 These figures are from the respective Wikipedia pages. I assume they have not been the subject of edit-war falsification by fanboys of planemakers. I wondered what might be the reason for the 737 seeming a much less safe plane. The 737 design is 20 years older? But it's still in production, so 1988...current 737s can be built with many of the same safety features found in an A320 produced the same year. Were 3,500 of those fatalities in the first 20 years? There are lots more older less-safe 737s being flown by corner-cutting budget airlines in third-world kleptocracies? Are there that many 40-year old 737s in the hands of incompetent airlines? The 8,104 737s have, on average, flown many times more cycles than the 6,171 A320s? But they address the same market, why would their usage differ so markedly? The 737s have, together, flown many times more passenger-miles than the A320s? See above. Plus I imagine older 737s have mostly been retired. My speculation doesn't seem very convincing to me. Is there a better explanation supported by reputable studies? <Q> For one, the early 737s had a design flaw which allowed the rudder to reach a hard-over position, and get stuck there. <S> Boeing initially dragged their feet in rectifying this, so it took a number of accidents before this design flaw was corrected. <S> This is a major contributor to the high number of fatalities in the early operational years. <S> To have a more meaningful comparison, I would suggest to compare the fatalities per year, so the status in operational procedures can be excluded as a factor. <S> As others have pointed out, this should give a more equal basis for a comparison. <S> If you look at fatalities per year , beginning in 2000, these numbers emerge: <S> Now you need to factor in the number of flight hours per type per year, which I do not have available. <S> But I would expect that the low fatality rate in the early 2000s is more due to the small number of A320s around. <S> But if we just compare the 737 NG with the A320, this advantage is reversed, and still the A320 comes out slightly ahead. <S> But thankfully, there are very few accidents for each type per year, so <S> the statistical base is too low for a meaningful comparison. <A> Raw numbers like this are more-or-less useless. <S> You would have to plot the accidents against the year to even begin to have something reasonable. <S> You also need to remove non-airframe accidents like: under-full-control crashes like controlled flight into terrain (pilot screwups have nothing to do with the airframe, and account for a lot of accidents) weather-related issues that are not pilot screwups <S> (e.g. microbursts downing Delta 191) ground collisions that resulted in insurance writeoffs ( a "hull loss") <S> maintenance whoopsies like not tightening the fuel lines operational errors (Tenerife put a major dent in the 747's accident statistics, nothing to do with the plane) External forces ( WTC attacks, various shoot-downs like Malaysian and Korean Air etc. ) <S> Once you look at 3rd-owner and beyond you may find yourself in the less developed countries with poor maintenance, training etc. <S> and then it gets a lot harder. <S> It's even tricky with first-line carriers. <S> Was Aloha Airlines Flight 243 (the Sunshine Roof flight) <S> a design flaw, maintenance not fixing it properly, operations not grounding it for maintenace etc. <S> etc. <A> As I mentioned in a comment earlier , there's no real way to answer this for certain: there are simply too many contributing factors to control for (many of which have nothing to do with the airframe). <S> Broadly speaking I suspect the 20 years more service time, much of it back when aviation accidents were somewhat more common, is a large part of it. <S> Boeing has a great presentation covering the commercial fleet accident rate from 1959-2012 , and just looking at the accident rate graph shows how far commercial air travel has come in cutting their accident rate. <S> That being said while I do enjoy mercilessly mocking Airbus aircraft <S> the A320 series has an enviable safety record, and certainly some part of that can be credited to the airframe and crew training programs in addition to the broader safety improvements in commercial aviation - just don't ask me to be specific as to how much ... <A> I'd suspect that the answer is a combination of a lot of factors, including all of the ones mentioned in the question. <S> •There are lots more older less-safe 737s being flown by corner-cutting budget airlines in third-world kleptocracies? <S> •Are there that many 40-year old 737s in the hands of incompetent airlines? <S> In short, yes. <S> They might not all be 40 years old, but, yes, there are tons of older 737s that were sold off to third-world airlines and/or airlines that simply operate in more dangerous areas. <S> It's probably the single most common jet airliner in such situations. <S> •The <S> 8,104 737s have, on average, flown many times more cycles than the 6,171 A320s? <S> •But they address the same market, why would their usage differ so markedly? <S> While I'm not sure that their average use cases are very different for aircraft of the same age, there are far more old 737s than old A320s. <S> A lot of the 737 fleet already had flown many cycles before the first A320 ever rolled out of the factory. <S> The average 737 is significantly older than the average A320 <S> and, thus, has flown more flight cycles. <S> While the first A320 delivery was in 1988, the vast majority of A320 deliveries have been since 2000 ( 5,029 A320s out of 6,171 in service were delivered 2000 or later .) <S> Based on their respective Wikipedia Orders and Deliveries numbers by year, the average fleet age of the 737 is a little over 16 years while the average age of A320s is only about 8.5 years . <S> Of course, this also means that there are a lot more old 737s to be sold to the aforementioned third-world airlines than A320s. <S> •The 737s have, together, flown many times more passenger-miles than the A320s? <S> •See <S> above. <S> Plus I imagine older 737s have mostly been retired. <S> In addition to the average 737 being significantly older (and, thus, having significantly more flight-cycles) than the average A320, you still have to consider that there are <S> 31% more delivered 737s than A320s. <S> In total, the B737 fleet has about 131,000 aircraft-years of history compared to about 52,800 aircraft-years for the A320. <S> So, aircraft-years of service alone explains a factor of 2.5 (half the difference.)
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So, in short, I don't think any one factor explains the difference, but the sum of several factors, most of them being related to age, does explain the difference. If we want to draw any conclusions, it could be that the A320 is indeed a safer aircraft, but the certainty of this conclusion is very low, being based on a very small number of accidents.
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Do stealth airplanes need to limit contrail generation? Stealth aircraft have low visibility on radar. I assume that they strive to achieve low visibility optically as well, e.g. spend some effort to not stand out too much visually from the surroundings. A condensation trail (during daytime against a bright sky) could definitely make an invisible aircraft visible. So what do stealth aircraft do against condensation trails? Do they have technology aboard to avoid or minimize them? Or it just a matter of choosing the right conditions (clouds, humidity, altitude, temperature) to fly? <Q> Do stealth airplanes need to limit contrail generation ? <S> Contrails form due to moisture in the aircraft's exhaust. <S> A tried and tested method by NASA is NOT to fly in regions of air that support contrail formation. <S> Ophir's Pilot Alert System which is used by the B-2 stealth bomber uses LIDAR (light detection and ranging) to differentiate contrails from clouds and tells the pilot to change his altitude as/when necessary. <S> That being said, it is essential to remember that though contrails are visible to the naked human eye they are NOT visible to Radars . <S> Ergo, until the stealth aircraft is really close (assuming it is on a SEAD/DEAD mission) one cannot see the contrails and by the time they do, it is too late. <S> Moreover, stealth aircraft generally operate during night when contrails are less visible. <S> Stealth aircraft have low visibility on radar. <S> Not necessarily. <S> VHF radar should be able to detect them at long range. <S> Moreover, RCS of aircraft is a complex phenomenon, depending on many stuff (frequency, aspect angle, polarization of signal etc). <S> You will never find a "static" figure for this. <A> Stealth aircraft include options to reduce visual signatures, so yes. <S> This is achieved as a side effect of reducing the infra red signature, which is done by mixing the engine exhaust with environmental air before it is ejected, cooling the air a lot and thus making contrail generation far less likely. <A> To directly answer your question, stealth aircraft have no special equipment to limit their contrails. <S> The military does though incorporate atmospheric data into their flight planning to minimize the creation of contrails especially during daytime operations. <S> This is true not just for stealth aircraft, but any aircraft which is concerned about being detected visually (such as reconnaissance aircraft, etc). <S> NASA has a website <S> that projects the formation of contrails. <S> Essentially it looks at the relative humidity with respect to ice (RHI) in the atmosphere, and if it is greater than 70% the region is flagged. <S> Areas with greater than 100% <S> RHI are very likely to support the formation of contrails.
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Not just stealth aircraft, most military aircraft are required to avoid contrails.
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Why do pilots disable the air-conditioning 'packs' during takeoff? I've realized that some pilots turn the air conditioning units (also called 'packs') OFF during takeoff, like in this video: LH456 Takeoff Video Is there any operational reason for that? <Q> The "packs" (or A/C on the aircraft) are powered by engine bleed air. <S> When bleed air is extracted from the engines, less thrust can be produced. <S> This may be a problem if the airplane is taking off at a high elevation airport or the departure path requires a certain climb gradient to clear obstacles. <S> This action does create some discomfort in the cabin <S> so it's usually not preferred unless required for safety. <S> Some newer airplanes are manufactured with an "APU to pack" configuration - i.e. the pilots leave the APU running during takeoff, which provides bleed air to power the packs. <S> The workload on the engines are now reduced. <A> Pilots will turn off the packs for takeoff if maximum engine performance is needed or if there is a need to prioritize a high demand bleed draw. <S> The particulars of the situations calling for a packs-off takeoff is airframe specific. <S> In the EMB-145, normal takeoff was with the APU bleed powering the packs. <S> The specific configuration calls for engine bleeds off, APU bleed on, cross-bleed valve open and packs on. <S> This lets the APU be the sole source of bleed air and the packs the sole consumer of bleed air. <S> This is a typical configuration, but assumes that the APU is operational and that anti-ice will not be needed. <S> If the APU is inoperative or anti-ice is called for, then the takeoff configuration becomes engine bleeds on, APU bleed off, cross-bleed off, packs off. <S> This isolates the APU from the bleed system (but keeps it available as a 5th generator) and makes the engines the bleed sources with no draw from the packs. <S> This configuration with the APU inop allows the engines to avoid a performance hit from the bleed air taps (drawing compressed air at the 9th and 14 compressor stages of this particular engine). <S> For anti-ice takeoffs, this configuration provides the ability to provide anti-ice as the APU bleed source is not powerful enough for this on the EMB-145. <S> The particular pneumatic configuration details will vary by airframe, and as mentioned in comments to the other answers, some airplanes have limitations on bleed valves being closed (e.g. to keep a pneumatic powered hydraulic pump operational) and some do not. <S> In summary, the reason for a packs off takeoff is likely for takeoff performance or for high demand needs such as anti-ice. <A> When I did my dispatcher certificate, we used the 727... and from my notes, you'd get a 1500 lbs increase in runway limit performance, with the Packs off.
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Best answer that I can think of, without the exact engineering or design info, is that since the A/C packs are run with engine bleed air, if you need the extra thrust from the engines, you'd turn off the packs for that extra power for take off...
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Why is the fatality rate in the Diamond DA40 so remarkably lower than the SR20/22? I assume it has a lot to do with the stall characteristics, but with the SR20/22 having a combined 1.6/100,000 Fatal rate and the DA40 having .35/100,000 Fatal, it seems like a very stark difference. Additionally, the SR-- has a ballistic parachute and the DA40 does not. <Q> Every added safety feature tends to make people more careless. <S> Was the same when airbags were first introduced in cars, accident rates shot up for a while before slowly trending down again. <S> Also, the DA40 is used more often as a trainer, while the SR22 is more often used by relatively inexperienced pilots who do have a license. <S> Might well make a difference (student pilots tend to be more aware of the limits of their skill and knowledge than cocky fresh graduates who think that now that they are certified to know it all they really do know it all). <S> And often that student will have an experienced instructor in the cockpit with him as well. <A> Compared to other 180 hp airplanes the DA40 handles strong cross-winds better. <S> It also has good visibility because the canopy bow is so far aft. <S> http://philip.greenspun.com/flying/diamond-da40 <S> In defense of the SR20 <S> what can be said is that the SR20 has a split-airfoil wing design that guarantees the wings will stall near the fuselage first, leaving the outer wings and ailerons unstalled. <S> The result is very controllable performance right up to and including the stall. <S> http://philip.greenspun.com/flying/plastic-airplanes <S> That being said, a majority of accidents involving the DA40,SR20/22 or any 4-seat GA airplanes is almost always caused by Pilot error . <S> So , it is not about the DA40 being more safe than the SR20. <S> Splitting high and low fleet hours may result in too high a number. <S> Ergo, the math is not precise. <A> Suggest you look at the design of the DA-40 vs the Cirrus aircraft. <S> Also compare the number of post-crash fires in each aircraft type (DA-40 has zero). <S> The Diamond's have dual spars in their wings, with fuel tanks between the spars (for crash protection). <A> If I had to place the blame on this one, it’s in the fact that the Cirrus aircraft are faster and more capable. <S> I suggest reading The Next Hour by Richard Collins about GA accidents and safety. <S> He talks at length about how faster, more aggressive airplanes tend to attract aggressive pilots who may lack the discipline to fly them properly or have extreme hubris in regards to their piloting abilities. <S> Add into this Cirrus’ somewhat deceptive marketing strategies where they seemingly tout the airplane as safe, almost to the point of invulnerable, with the CAPS system. <S> The general public’s and GA pilot pool’s ignorance of the capabilities and limitations of safety features combined with the high performance of the airplane as well as the large scope of private pilot privelages in terms of airplane performance also aggravates this. <S> This make for a situation ripe for accidents to happen. <S> To be fair <S> the Cirrus SR20 and SR22 are excellent, docile and safe airplanes IF OPERATED PROPERLY. <S> And the SR20 has an excellent safety record, comparable with the DA40. <S> But the fly faster and operate faster in the pattern than does the Diamond. <S> And considering that 50% of GA accidents happen on approach and landing, at low altitudes at higher speeds with more impact energy where the chute is inefficitve as an escape system, it’s <S> no wonder an SR-22 has a higher accident rate associated with it.
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Not sure how true it is, but one theory I've heard about the high accident rate of the SR22 is the parachute. The Diamond's also have robust fuel lines that resist pinching and breaking in the event of a crash.
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What is the advantage of the two-part rudder and how does it work? I saw that some aircraft's rudder is composed of an upper rudder and a lower rudder (B727, A380, ...) as illustrated: Image Source I wonder how does it work compare to a normal rudder and what are the pros and cons of the two-parts rudder over the one-part rudder? <Q> This is called Split Rudder and it provides redundancy. <S> They run on different systems so if one fails, the other one can be used. <S> Here is a picture of a split rudder: <S> Very importantly, there is a structural benefit. <S> When we use the rudder it imposes a twisting load on the vertical fin. <S> By only using the lower rudder, when the aircraft is at high speed, we reduce the twisting moment and transfer that load to a bigger, stronger, part of the airframe. <S> The principle is the same as why the outboard ailerons are disabled at high speed. <S> The patent information is here . <A> As pointed out by Farhan, it adds redundancy to the aircraft. <S> A 747 once experienced a rudder hard over . <S> Even with the split rudder design, the crew had to rely on asymmetrical thrust to control the aircraft. <S> If it had one very large rudder surface, control would be much more difficult, or may even be impossible. <A> It allows one part to jam while the pilot retains control over the other part. <S> Also the higher portion of the rudder induces roll <S> when deflected, at high speeds (where control surface deflection is more effective) <S> only the lower portion can be deflected to minimize this effect.
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Split rudders also provide a finer high speed control, in that only the lower one moves at high speed, reducing the exposed surface area and therefore the control effect.
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Where does the APU draw its intake air? In an airliner, where does the APU draw its intake air? Is it a similar location for all airliners, or do different options exist? <Q> Aircraft place the inlet in different places though, and some even put the APU somewhere different. <S> For some examples: 737 intake, the small NACA inlet at the bottom <S> E145 <S> (the place they don't want you to put de-icing fluid) <S> B777 <S> (the scoop that opens upwards) <S> A330 <S> (a scoop on the underside of the tail) <S> B727 (inside of the wheel <S> well) <S> Here is an interesting thread including other examples. <A> The specific location varies a bit with each aircraft, but in general, they are located close to the APU - so in the tail. <S> Many aircraft will have a door on the top of the fuselage that opens when the APU is running, while others have an inlet that is always open, like on the 737. <A> The Boeing 737NG APU inlet is on the right side of the tail cone and the exhaust is Through the tail.
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The APU is usually located at the rear of the aircraft, in the tail, so the intake is generally somewhere on the side of this location.
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Why are the lights inside commercial airplanes turned off during take off and landing? Before landing and taking off, I notice the lights inside commercial aircraft are greatly reduced. I don't buy the explanation of power saving in case full thrust is needed as nowaday lights don't need a lot of energy and the crew says we can use the smaller reading lamp to continue reading. I suppose this is something to do with security but I don't understand what. <Q> This is for safety reasons. <S> Take-off and landing are the two most critical phases of flight and thus, every additional step to ensure survivability, be it even just adjusting the light, is taken. <S> The interior lights or cabin lights are adjusted to match the exterior environment, so that in case of an emergency, especially if the interior lights fail, your eyes are already accustomed to the light setting and you do not require additional valuable seconds for adjustment to a possibly darker or brighter environment. <S> The lights are usually adjusted at dusk, night or dawn to match the exterior environment. <S> 1 <S> The bright emergency lighting is more prominent to identify when the cabin light is dimmed, saving valuable seconds as the aircraft is evacuated. <S> This also ties in with having to raise the blinds on the windows. <S> The blinds need to be raised during take-off and landing irrespective of the outside light situation, however, with a darker cabin, any outside light source, especially from fires or other hazards is easier to identify by the crew, making the decision process of whether one side could be inappropriate to use for evacuation faster, e.g. fire on port side -- <S> > <S> no evacuation on that side. <S> The blinds are therefore raised to allow a better view for cabin crew of the outside area and external aircraft parts, such as engines, wings, etc. <S> See also this related question: Why open up the window shades before takeoff and landing? <A> My flight instructor told me that also, when taxiing at night (that is, before taking off or after landing), lights should be kept at a minimum as a courtesy to other pilots. <S> A bright line of full lit cabin windows could distract or mask other dimmer lights like the taxiways blue ones. <A> You are right. <S> The 'power saving' theory is nonsense. <S> Most of the time, except at 'hot and high' airfields, aircraft take off using much less than maximum engine thrust (known as de-rated or 'FLEX' thrust setting), so turning off the lights to reduce the generator load doesn't make any sense. <S> It is also worth noting that cabin crew require the lights to be dimmed during landing as well, not just take off, and that would have no 'power saving' benefit whatsoever. <S> The A/C packs may be turned off during take off because they use bleed air from the engines, which does have an effect on thrust output. <S> This would only really be necessary with a high take off weight or short runway. <A> Cabin lighting has no impact whatsoever on takeoff power. <S> None. <S> Reducing cabin lighting does not increase power available for takeoff. <S> Cabin lighting is dimmed for takeoff to help ensure that emergency lighting is most visible. <S> Reduction of cabin lighting aids in dark adaption. <S> I have never seen an aircraft performance chart or program that accounts for cabin lighting on or off to determine available power for takeoff... <S> because with respect to available takeoff power, cabin lighting is irrelevant. <S> And yes, we do dim lighting during arrivals and departures in Afghanistan. <S> It still has nothing to do with takeoff power.
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If the cabin lights do not fail during an emergency, the dimmed light also makes it easier to identify the "EXIT" signs which illuminate and make the guidance lighting on the floor easier to follow.
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How can I take 360° panoramic pictures in an aircraft or helicopter? I would like to receive some answer or advice on how to create 360 panorama images.My plan is to use Cessna or Helicopter. <Q> This is as much a photography question as an aviation one. <S> The type of aircraft you might want depends on the type of picture you want. <S> This would let you hover in one spot, and rotate to cover the full panorama. <S> The movement of the aircraft could easily be compensated for in processing the photos. <S> A quadcopter holding a position by GPS should be very stable for long enough to take the photos. <S> If your picture is at a higher altitude, focusing more on things further away, a small plane could work. <S> Many general aviation aircraft can fly fairly slow. <S> With only more distant objects as the subject, a plane in a turn at under 100 knots should be slow enough that the perspective change would be negligible. <S> If you could get something like a simplified version of Google's street view setup, and send it up on a quadcopter, that would probably give the absolute best result. <S> See also this more general question: What is a good plane for aerial photography? <A> My advice would be an aircraft is a lousy tool for this - airplanes in particular. <S> An aircraft is always moving - airplanes have to move in order for the wings to generate lift, and even a helicopter hovering is going to be moving based on wind, thermals, and downwash from its own rotor. <S> Movement makes panoramic imaging difficult since a lot of the modern camera tricks we use to capture panoramic images "in camera" involve rotating the camera (think iPhone/Android "panorama" shots, or the old-school camera-on-a-stick systems used for film photography). <S> With a fixed-wing aircraft that motion would cause misalignments that would make stitching the images together difficult (because the perspective would be changing between shots). <S> Difficult doesn't mean impossible though - <S> It's been done on quadcopters ( Adobe even has a tutorial where they stitch together a panorama using GoPro camera images), and you could do the same thing with a camera mounted on a full-size helicopter. <S> You could probably make it work for a fixed-wing aircraft too, but it would be better if you had a rotating camera mount (rotating the whole airplane would change the perspective, but flying very slow and spinning the camera reasonably fast you'll probably get usable images). <A> Phantom 2 Vision are VERY high-quality drones, perfectly suited for what you are looking for, and I believe they come with their own imaging equipment.
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If you want a picture from low altitude, showing the area nearby, a helicopter or a quadcopter (depending on local regulations) would be ideal.
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What can I do on the ground in order to help my body acclimate to aerobatics? I've just started aerobatics training! Unfortunately, my middle ear really messes with me, particularly during loops. Strangely, aileron rolls give me no trouble at all. I know from other experienced aerobatic pilots that you can get used to aerobatic flying, and my tolerance will build up over time. However, is there anything I can do on the ground in order to help build up my tolerance more quickly? <Q> The way the Air Force introduces people to the disorienting effects of aerobatics on the ground is to put them into smoothly spinning chairs called Barany Chairs . <S> And it doesn't just involve spinning in one direction, but smoothly and gently changing directions repeatedly. <S> Since I never suffered from airsickness, I don't know what they do (i.e. do they blindfold you, <S> are there more than one axis of motion <S> , do you have to tilt and move your head, etc.) <S> While an actual Barany Chair may be expensive, you could perhaps accomplish the same with a friend and a nice heavy office chair. <A> As you've mentioned, your tolerance will build up over time so a simple, partial answer is to be patient and fly in small doses . <S> Two 20 minute flights with a break between is much much better than a single hour long flight. <S> You'll learn more, stay focused, and acclimate faster. <S> Try not to move your head much during maneuvers . <S> For a loop, I typically look at my left wing tip until I'm about 3/8's through the loop, then I transition to looking "up" to catch the horizon as I approach the top of the loop. <S> Any more movement than that might be a problem. <S> Bill Thomas's classic book Fly <S> For Fun describes where to look for many of the basic maneuvers. <A> I used to feel strong motion sickness when flying aerobatics. <S> I got to the point I could burn off the acro tanks in an Extra 300 without getting sick. <S> I did 3 things: 1) Repeatedly spinning in an office chair until I felt dizzy then getting up and walking. <S> 3) <S> If you're in a car and not driving, try reading until you start feeling sick. <S> Somehow I never threw up flying aerobatics, but I did come really close a number of times. <S> I tried to relax, control my breathing, bring a little water with me, and always push myself a bit. <S> And somehow that worked for me. <S> Also if you do some aggressive maneuvers like lomcováks, long tail slides, push humpty-bumps, and accelerated spins, most other maneuvers will seem much more tame and you'll be able to relax and enjoy them. <S> Good luck and have fun!
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2) Flying as much as I could, and when I did, I would fly until I felt sick, then fly straight and level until I felt a bit better, then would do an avalanche maneuver (snap-roll at the top of a loop), then would fly straight and level again... and do it again, gradually pushing myself.
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Why is the "Dutch" roll called so? Why is the "Dutch" roll called so? When did this name enter common usage, and what is its origin? Please cite sources if possible! <Q> According to Wikipedia : "The origin of the name Dutch roll is uncertain. <S> However, it is likely that this term, describing a lateral asymmetric motion of an airplane, was borrowed from a reference to similar-appearing motion in ice skating. <S> In 1916, aeronautical engineer Jerome C. Hunsaker published the following quote: "Dutch roll – <S> the third element in the [lateral] motion [of an airplane] is a yawing to the right and left, combined with rolling. <S> The motion is oscillatory of period for 7 to 12 seconds, which may or may not be damped. <S> The analogy to 'Dutch Roll' or 'Outer Edge' in ice skating is obvious. <S> " <S> By 1916, the term had been imported from skating to aeronautical engineering, perhaps by Hunsaker himself. <S> 1916 was only five years after G. H. Bryan did the first mathematics of lateral motion of aircraft in 1911." <S> Sadly, this question is probably not answerable beyond what wikipedia has on this site (unless there is an English Major looking for a Ph.D. thesis. <S> ;) <A> An early use of "Dutch rolls" in aeroplaning is 1910: <S> Fancy aeroplaning was on the programme at the Harvard Aviation Field the next day, with Ralph Johnstone and Walter Brookins as the star performers. <S> They demonstrated their skill with the biplanes until Wilbur Wright feared for their safety and ordered them to desist. <S> Johnstone's favorite stunt was to indulge in steep volplanes, shutting his engine almost completely off and floating lazily for a moment on an even keel, then suddenly shooting down through space until het almost touched the ground. <S> Then would follow a series of Dutch rolls as he swooped up and down close to earth. <S> Conquest of the Air by Airships and Other Flying Machines, Jay Henry Mowbray, 1910. <S> (Link) <A> In Dutch, this motion is called zwierbeweging: swaying motion. <S> Indeed the motion that can be observed during ice skating on modern metal skates. <S> I unfortunately have no official reference other than videos of for instance this event . <S> Swaying Dutch roll everywhere.
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In 1916, Dutch Roll was the term used for skating repetitively to right and left (by analogy to the motion described for the aircraft) on the outer edge of one's skates.
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What's that component between the engine and wing? It's on most commercial aircraft and large aircraft with turbofan engines... Is there a specific name for it? Does it serve any other functions apart from attaching to the wing and feeding the engine the essentials? Has there been any aviation incidents that involved something malfunctioning or breaking inside of it? Or some other interesting things about it? Just out of curiosity! Thanks! :) <Q> And yes, some designs use specific points designed to fail if there is excessive force, allowing the engine to separate from the aircraft without ripping the entire wing apart which would obviously be a catastrophic event. <S> It has happened on a few occasions. <S> The above image is from the Wikipedia page on the American Airlines 191 accident , where, due to a faulty maintenance practice of using forklifts for removing and reattaching the engine/pylon assembly, the aft bolts were damaged. <S> The pylon eventually failed, allowing the engine and pylon to push up and over, separating from the wing. <S> Other examples include China Airlines 258 and El Al 1862 . <A> It's a pylon and indeed just hold up the engine and connects it to the craft. <S> They are designed so that excessive force will cleanly separate the engine without damaging the wing. <S> American airlines flight 191 had the pylon fail in midair due to mishandling of the engine during maintenance. <S> 2 engines separated in El Al flight 1862 ; in this case the inboard engine separated cleanly but then slammed into the outboard engine where it did damage the wing. <S> The same thing happened a year earlier in China Airlines flight 358 . <A> This part is called the "pylon" or "strut" for the engine. <S> The strut is designed to prevent a fire in the engine area from spreading to the wing. <S> Mounting the engine below and forward of the wing leading edge provides some advantages over other options . <S> Once the strut is installed on the wing, it is intended to be permanently attached there. <S> As shown in falstro's picture , the engine mounts are installed on the engine, and allow engines to be installed and removed as needed. <S> When no engines are installed, a weight is suspended from the strut to balance the aircraft and prevent the plane from tipping backwards . <S> There are differences in design between manufacturers. <S> Boeing struts are designed to break away from the wing under extreme loads. <S> The strut attaches to the wing using fuse pins, which will fail at a specific loading, lower than the strength of the wing. <S> This prevents the wing from breaking under the load, which could cause the fuel tanks to break open and start a fire. <S> Examples of engines breaking away as designed are the Asiana 214 and Lion Air 904 incidents last year. <S> Airbus struts are designed to remain attached to the wing . <S> This actually allows the structure to be less complex, and Airbus struts tend to be noticeably more narrow than comparable Boeing struts. <S> Other methods are used to maintain safety in a crash, such as keeping the area directly above the engine as a "dry bay", which is not used to store fuel. <S> Here is an Airbus patent for a strut design using composite panels, which describes the strut. <S> As mentioned by falstro, there are multiple incidents where the structure in the pylon has failed, resulting in the engine coming off of the plane in flight. <S> There have been both design and maintenance causes for such incidents, and both design and maintenance changes have been made to address those issues.
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It's a hard-point called an "engine pylon". It holds the engine on the wing, provides a path for all of the engine systems to connect, and includes the aerodynamic fairing to cover it all.
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How are maps loaded in UAVs? My question intends to find out how maps are downloaded/buffered at Ground Control Station's for UAV operations. I understand GPS transmitters relay the exact location of an aircraft on a map. However, the map needs to be loaded/buffered in real time as the UAV covers ground. For a UAV as large as the RQ-4 Global Hawk , with a range of 14000 kms, how is the map loaded in real time? On the other hand, for amateur or small scale UAVs/ MAVs , is the map updated in real time as the aircraft/rotorcraft covers more ground? Or is that the map is downloaded pre-flight, based on the range of the aircraft? This would be preferable in terrains with poor or no signal connectivity. <Q> You seem to assume the maps are being transmitted from the UAV. <S> They are almost certainly not (and if they are that's a poorly engineered system and <S> I would be embarrassed that my government wasted my tax dollars on such a lousy design). <S> Maps are relatively static data, so it would be logical to store them on the computers at the ground control station (where you could have the entire world's terrain and likely aeronautical charts/airspace boundaries on your hard drive, along with current weather data and other useful information). <S> Moving the map to keep up with the position being relayed from the UAV is computationally trivial: iPads do it for real aircraft ( ForeFlight & similar products) and <S> your car's GPS system does it when you drive - neither system is as powerful as the typical desktop computer. <S> All the UAV would relay to the ground station is its position (and any other pertinent data dictated by its mission, such as photos/video). <S> This arrangement minimizes the bandwidth required to control the vehicle, as well as its RF signature (less stuff to transmit back to base). <S> For autonomous UAVs, particularly ones which have to avoid airspace incursions, some subset of airspace data appropriate to the route of flight may be loaded on the vehicle, but I wouldn't call these "maps" <S> - it's a much more compact representation of coordinates marking boundaries in 3D space (similar to the Jeppesen NavData products - possibly even using those products) . <S> Such vehicles may also have terrain data loaded before flight if they lack other means to avoid collisions with terrain while operating autonomously. <S> Disclaimer: <S> I have no experience with the RQ4 or any other military UAVs - this is just a common-sense engineering assessment. <A> For an application that were controlling a hobbyist UAV one could use something like the Google Maps API. <S> It provides services and data that will scale as the user scrolls in and out and as the UAV transitions to different areas. <S> It also has the advantage of having visual and road data as an option. <S> The downside is that unless you download enough data ahead of time you must have some sort of data connection to the application. <S> But, with the greater availability of the fast cell based data connections this is becoming less of an issue. <A> Formal flying charts are loaded underneath a 'moving map' display. <S> The pilot can select a wide variety of charts from a small scale GNC to a large scale VFR chart. <S> There is a limit to the buffering obviously, and if the aircraft flies outside of the buffer than the pilot just manually loads a new map for the new area. <A> Amatorial drones: normally these boards have flash memory as not-mandatory <S> , everything has to be loaded in to RAM or on limited space on-board. <S> Also communication between UAV and GCS is not mandatory. <S> Most complete (open) GCS + software seems to be ArduPilot, and its trick is that the map is only PC-based; you set your travel point (waypoint) on GCS, connect the UAV by cable if no wireless link is present, upload the waypoint GPS coordinates, and let the mission begin. <S> If you have a wireless link you can obviously load or edit waypoint on-the-fly. <S> Now think about this: how a map should be helpful to a drone? <S> Because he may recalculate the route on its own. <S> But why should it do so?Drones normally are "blind" to environment, and <S> radar/lidar/vision items are complex, expensive or require a lot of computing power and space on the drone. <S> In that case adding a microSD with the map in full precision of the region you are gonna fly is not a problem (OpenStreetMap planet map is about 40GB), but again I assume the pathing algorithm would just override the waypoint setting every time <S> a course correction is needed, and another specialized algorithm would kick in to avoid low-term collision, which ignores completely the route. <S> Please note that many drones have a "return to home" function, that when the link is lost and mission complete, the drone heads directly to home. <S> And as many amatorial drones are blind, that may have unexpected results.
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Military UAV's have a library of maps (on a hard drive associated with the ground control station) that the pilot chooses from while flying.
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Why tail wheel rather than tricycle? I'm working towards my tail wheel rating and enjoying it greatly. But, people ask me why some planes have a conventional landing gear (tail wheel). Why indeed? I understand perhaps why they had them originally, but is it just historical reasons? Seems like maybe it can have slightly lighter gear and perhaps simpler design, but I'm wondering if there are deeper reasons. <Q> Ratchet freak gives already most of the reasons. <S> I might add that on a grass field the taildragger is easier to handle. <S> On a hard surface, however, the tricycle gear is easier to handle. <S> If you look at modern airplane designs, those where weight must be kept low (like aerobatic planes) still have a taildragger gear. <S> It is also used in gliders and motor gliders, because they will operate mostly from grass strips and do not want to include internal space to accommodate three retractable wheels. <S> Big taildragger designs from the early days vanished with the emergence of concrete runways from the 1930s on and the need to brake more during rollout when wing loadings and landing speeds went up. <S> On concrete runways, the tricycle gear handles better and gives much better visibility . <S> Without the ability to brake hard, the rollout lengths of taildraggers would prohibit todays wing loadings. <S> With retractable gears the drag disadvantage is no more, and the increased weight can be tolerated. <A> It's a fiery debate. <S> One of the reasons for the taildragger design is indeed weight. <S> There is also that the plane will naturally sit at a positive angle of attack and will keep the propeller further off the ground. <S> Rotation is assisted by gravity because the CoG is behind the wheels. <S> Also getting a tailstrike on takeoff isn't critical. <S> The reasons for the nose wheel design is increased control during takeoff (with the tail dragger there is a period where the tailwheel is off the ground and yaw control is up to the rudder) <A> Some nose wheel gears are fragile and would not survive well on unpaved runways. <S> Also the distribution of weight is a factor. <S> There is less weight on a tail wheel than a nose wheel. <S> Therefore most of the weight of a conventional gear aircraft is split between the mains. <S> Use of a conventional gear on an soft runway eliminates the issue of the nose wheel digging into the surface.
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The relatively high drag and long lever arm of the tailwheel or skid will help to pull the aircraft straight at low speeds when rudder control power is low. Also, not only the weight, but also the drag of two wheels is less than that of three.
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Do aeroplanes have to balance torque like helicopters? Helicopters need a tail rotor to balance the torque reaction that tends to rotate the main body sideways. Doesnt a single-engine plane suffer the same problem? I would imagine that (for example) the left wing would dip lower than the right due to the torque. How is it countered? <Q> A single engine plane can suffer from control problems due to torque. <S> An early famous example was the Sopwith Camel <S> Some aircraft had extra-large ailerons because of this issue. <A> In contrast to what happens in helicopters, the static and dynamic stability will prevent big movements of propeller aircraft due to engine and propeller torque. <S> The biggest consequence, the rolling moment, is taken care of by roll damping. <S> When the propeller torque rolls the aircraft, the downwards-moving wing will see a higher, and the upwards-moving wing a lower angle of attack. <S> Both wings will create a rolling moment which will quickly stop the rolling motion. <S> All the pilot has to do <S> is to restore the correct roll attitude using the ailerons. <S> The lift difference of the rolling aircraft also creates different drag on the left and right wings, so a small yawing moment will turn the aircraft slightly sideways when the rolling starts. <S> This has to be corrected by rudder input. <S> If we look at other secondary effects, the yawing motion will cause a slight pitch change by way of engine and propeller precession. <S> This also will be stopped quickly by pitch damping (the pitch movement changes the angle of attack on the horizontal tail surfaces), and the pilot needs to correct the pitch attitude again. <S> In consequence, changing RPM will induce slight movements around all three axes in a single-engined propeller airplane. <A> It is countered by the natural stability and the roll control provided by the ailerons. <S> If you have insufficient airspeed for roll control then you will be on the ground and your gear will prevent excessive rolling. <A> There is a big difference between the amount of torque delivered to the main rotor of a helicopter and that delivered to the propeller of a comparably-sized fixed wing aircraft. <S> Also, without the tail rotor, a helicopter in a hover has nothing to "push against" in order to deliver the needed torque to the main rotor. <S> If not for the tail rotor, torque delivered to the main rotor would cause the rest of the vehicle to spin up in the opposite direction. <S> Hovering flight would be pretty much impossible without something to aerodynamically generate opposing torque (tail rotor, second counter-rotating rotor, etc.). <S> Torque delivered to the propeller of a fixed-wing aircraft is opposed either through the ground (when stationary, taxiing or on take-off roll), or by the wings (with minor roll trim or control input) when in flight. <S> As explained in the other answers, propeller torque does induce certain effects, but they are of much less significance than that of a helicopter main rotor, and are dealt with by trim and pilot awareness/handling. <A> Torque is more noticeable in aircraft with tail wheels (tail draggers) which also have large engines ( <S> e.g. world war 2 vintage) for two reasons: <S> If the throttle is advanced too quickly, you might not have enough airflow over the rudder to be able to counteract it and a swing followed by a ground loop could result. <S> At the point when the tail is lifted off the ground during the take off run, gyroscopic effects occur that could cause a swing (try holding a spinning top and then move it around - it exerts forces in unexpected directions). <S> Also on aircraft with the largest engines, the torque could make one wing lower than the other during the take off run. <S> You also have the problem going around to be very careful with both throttle and rudder because these effects are more pronounced at lower airspeeds where airflow is less. <S> An aeroplane with a nosewheel is generally more stable on the ground (due to the CG being ahead of the main wheels rather than behind), so these effects are less noticeable.
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As others have pointed out, torque effects have to be countered using the normal aerodynamic controls available to the pilot.
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Is the climb rate different for short-haul flight and long-haul flight? A short-haul flight does not spend much time in its cruise level (let's say less than two hours). Thus, it is important to rapidly reach the optimal flight level and I think this kind of aircraft should be optimised to climb. On the opposite, on long-haul flights there the climb and descent reprsent a tiny portion of the whole flight. The aircraft should then be optimised to consume as little fuel as possible during cruise, even if climb rate is less important. That's why I wonder if my thinking is right and if there are significant differences in climb rate between short and long-haul aircraft. Related thinking: On average, does a short-haul flight descent more rapidly than a long-haul? I think not as this diving has no reason to be related to climb/cruise performance and all commercial aircraft are made to use the same airports with the same approach pattern; but that's only an assumption. EDIT: OK, the quantity of fuel is quite important. I suppose an aircraft designed to be heavier (long-haul, carrying lots of fuel and payload) is equipped with more powerful engines and thus if it is lighter than designed for (lets say a B777 or a A330 used on short-haul flights), it climbs faster than the same aircraft in a long-haul flight. But the long-haul aircraft is designed to make long-haul flights. Maybe I should have asked if there is a significant difference in climb rate between short and long-haul aircraft at their maximum operating take-off weight. <Q> Different climb performance is indeed indirectly linked to the length of the trip, but this has to do with the number of engines. <S> All airliner's engines are sized to support flying with an engine failure right after take-off. <S> Twin-engined aircraft enjoy slightly less stringent rules, but will basically carry twice the thrust that they need to stay aloft, so more excess power is available than in four-engined aircraft, which have only 33% excess thrust. <S> Generally, the best performance is achieved when running the engines at their maximum continuous thrust setting and when climbing as fast as possible. <S> That is the reason why an A-320 or a Boeing 737 will climb faster than an Airbus A-340 or a Boeing 747. <S> The link between engine numbers and range was strongest in the early jet age; now it is less clear-cut with long-range airplanes like the Boeing 777-200 <S> LR or short-range airplanes like the BAe 146 . <A> No, not for the reasons you ask about. <S> Absent restrictions due to other traffic, terrain or weather, pilots will always choose to maintain the best rate of climb speed ($v_y$, a.k.a. "green dot speed") and run the engines at the recommended climb power, simply because that's when the plane flies most efficiently. <S> The actual performance differs due to weight and weather, but that is not directly related to length of the flight leg. <S> Similarly the descent is again flown in a way that makes it most efficient (I believe that means close to maximum rate without speed brakes), which is again not directly related to length of the flight. <A> Short answer: <S> yes. <S> Long answer: on a long haul aircraft, it carries a lot of fuel for the next 12 hours. <S> That extra weight has quite an impact on climb performance. <S> E.g. it takes more time for a fully loaded B777 to climb to 10000 feet, compared to a B777 configured for short haul. <S> (Yes, many Asian airlines use B777 for short haul trips. <S> The shortest one I can think of is CX flying Hong Kong to Taipei, a trip less than 2 hours) <S> Long haul flights also just cannot climb that high. <S> The pilots can crank the engines max <S> and it'll just go perhaps FL270 - FL300. <S> Once after few hours, they burn up some fuel than climb, up to FL390 or higher. <S> These are called step climbs : burn some gas, climb a bit, burn some more gas, climb again, and so on.
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What short flights do is stop the climb at lower altitude (than permitted by load), because the time spent on higher level would be too short for the lower fuel consumption to offset the additional fuel needed to get there. On descent, the number of engines is less relevant, so the descent speeds of all types are similar.
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What can pilots do to spot the onset of hypoxia? If there is a loss of/lack of air pressure at high altitude, without an explosive decompression (for instance as on Helios 522 or N47BA ) are there any signs that pilots can look out for that they might not be getting enough oxygen? Does an audible alarm exist on any commercial jets when cabin pressure is at a dangerous level? It's my understanding that the brain is impaired, and reaction times are increased with oxygen deprivation. Are there any techniques to combat this, after noticing hypoxia onset? e.g. slowed breathing <Q> Yes, all pressurized aircraft have cabin altitude (= altitude at which the same pressure as currently in the cabin normally occurs) indicator with alert when it exceeds safe value. <S> On Helios 522 that alarm did sound. <S> The crew however mistook it for configuration alarm which only makes sense during take-off roll and thus considered it spurious. <S> When the technician they called realized it was cabin altitude warning, the pilots were already too confused to carry out his orders. <S> The symptoms are already listed in the other answer. <S> The problem is that the initial symptoms feel just like fatigue. <S> One starts to feel sleepy and at that moment one might not realize it could be due to hypoxia as mental capacity is already reduced. <A> A good amount of information can be found in the Operator's Guide to Human Factors in Aviation : <S> Hypoxia can be recognized from both objective (i.e., capable of being perceived by an observer) and subjective (i.e., perceived by the pilot only) symptoms. <S> Objective signs include increased rate and depth of breathing, tachycardia, cyanosis (blue-colored lips and nails), mental confusion, anger, euphoria, poor judgment, loss of muscle coordination, slouching and loss of consciousness. <S> Behavioral changes may be noted by the hypoxic individual, as well as by the observer. <S> The subjective symptoms include breathlessness, apprehension, headache, dizziness, fatigue, nausea, hot and cold flashes, blurred vision, tunnel vision, tingling, and numbness. <S> The only way to reverse the effects of hypoxia is to provide the lungs with a greater partial pressure of oxygen. <S> This can be done using either supplemental oxygen (mask), or descending to a lower altitude. <S> Corrective action must be taken quickly, as any delay makes the effects of hypoxia worse. <A> The FAA offers a training course for this: http://www.faa.gov/pilots/training/airman_education/aerospace_physiology/
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One option is to experience hypoxia in a controlled setting first, such that you know what altitude you might start feeling symptoms around and which symptoms are the ones you tend to express.
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Is the hydraulic fluid artificially colored? A normal aircraft has multiple hydraulic circuit, identified by colors (e.g. according to the ATSB final report of the QF32 the green hydraulic line was disabled; according to the BEA final report of the AF4590 the Concorde had a yellow, a blue and a green circuit, ...). I understand the need to be equipped of several independant hydraulic system (redundancy) and the need of being able to identify those. Thanks to the previous example, I figured out the hydraulic circuits are identify by colors. Does it mean the hydraulic fluid is colored (useful in case of leak)? Does it means the elements of each circuit is painted accordingly (usefull for maintenance)? <Q> A common hydraulic fluid used in aircraft is called Skydrol . <S> The FAQ on the manufacturer's site addresses the color. <S> Skydrol fluids are given a purple dye to make it easy to distinguish them from other fluids. <S> But the dye does not usually last as long as the fluid does. <S> The color may change from purple to gray or yellow or green, yet the fluid can still meet all used fluid specifications. <S> A dark amber color, however, is a cause for concern, and can indicate a severely stressed fluid. <S> Call Solutia's Technical Service for assistance if you are unsure about a fluid's color. <S> Our technical bulletin has a color chart to use as a guide. <S> Initially the color helps to distinguish from other fluids, and <S> having multiple colors would make it more complicated. <S> It notes that the color also does not remain constant, so even if it were colored initially, it would probably end up changing anyway. <S> It also mentions that a dark amber color can be an indicator of issues. <S> I can't find any good pictures, but the lines are probably not color coded. <S> The lines themselves can be labeled , but the standard for hydraulic lines is blue and yellow . <S> The end fittings are colored to identify the tube material type. <S> The maintenance manuals will show the layout and label the different lines. <S> Also, on this ASRS page , one report is from a mechanic that confused the green and yellow system fittings, which probably wouldn't have happened if they were color coded. <A> It is just the components that will be labeled accordingly. <S> Having each fluid be colored differently is a maintenance nightmare, you need to have all 3 colors available in the hangar and each system must be fully isolated (3 different pumps, buffers, actuators etc.) <S> to avoid contamination. <A> The colour codes of hydraulic systems referred to, common for 1960's-1970's British Jets, and since then all Airbus aircraft, do not refer to the colour of the fluid! <S> It is just an identification system for each separate hydraulic branch, the fluids themselves have nothing to do with 'green, yellow, blue' system identifications. <S> It should also be noted that the American convention is not to use colour codes, on Boeings they typically refer to 'left, right and center' systems. <S> In terms of the fluid itself, the original question mentioned Concorde. <S> Concorde used Chevron M2V 'Oronite' fluid, which is silicate ester and is a light straw colour. <S> Almost all civilian airliners used one of the main fire-resistant phosphate ester fluids, either Skydrol or Hyjet - phosphate ester is also naturally a light straw colour, but as specified it is artificially dyed purple for identification. <S> However, phosphate ester aviation hydraulic fluid changes colour when overheated, getting darker, turning from purple to dark purple to grey, to black in extreme cases - or if it leaks and becomes oxidised it turns back to the normal straw yellow colour. <S> Final mention is for many business jets(Gulfstreams and Citation X excepted) and <S> military aircraft, they use 'red oil' hydraulic fluids, either Mil-5606, 87257 or 83282. <S> They again are probably a straw colour to begin with, but are artificially dyed red per their relevant specifications. <S> You can generally mix the different red oils, or you can mix the different phosphate esters, but never ever mix red oil and phosphate ester - they have different seal swells etc. <S> Getting back to the original question: you don't use fluid colour to identify the system, you use the system schematics and the tube/hose identification labels. <S> The colours 'blue/green/yellow' are primarily for illustrative purposes in the pilot operating manual and system descriptions - go to smart cockpit dot com for exmaples.
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Any colored hydraulic system components are generally purple (like the fluid). The fluid is artificially colored, but this does not depend on which circuit it is in. Color is not a reliable indicator of fluid quality , and we recommend that the system be sampled for chemical analysis to determine if it is suitable for use.
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What is the purpose of VFR-on-top? VFR-on-top is an IFR clearance in the US that a pilot can request to allow an IFR flight to use VFR altitudes provided that it can remain in VMC. Requesting and receiving a VFR-on-top clearance doesn't cancel the IFR flight plan. When is this clearance useful? It allows the pilot a greater choice of cruising altitudes, but why would a pilot prefer to use VFR-on-top rather than request a different IFR altitude? VFR-on-top adds at least one task to the pilot's workload - maintaining VFR cloud clearance - without reducing the IFR workload. <Q> The VFR on top clearance is often given with a block of altitudes. <S> Such as this from the reference document "Maintain VFR-on-top at or between six thousand and one zero thousand.” <S> This flexibility can be useful with the conditions are such that the clouds come and go as you fly along. <S> So if you are cruising along at 6500 and encounter a cloud and need to climb to 8500 to maintain clearance you just do it. <S> No need to contact ATC and wait for them to ensure they can clear you higher while the clouds keeps getting bigger and bigger in the windshield. <S> Even if there are not cloud issues, the ability to change altitudes may be useful in seeking an altitude with more favorable winds. <A> Being in VMC has several benefits over hard IMC, especially if you don't have an autopilot, so being on top has advantages. <S> : <S> Manual flying with visual reference to the horizon is much easier and less strain than manually flying using instruments for attitude control Being out of cloud <S> enables a pilot to see and avoid traffic <S> Flying in cloud can be bumpy, VFR on top is often much smoother <S> Icing is a hazard when flying in cloud, <S> being on top of them means you won't ice up VFR on top works <S> well when you have a stratus layer that has an even top, <S> not so well when you have clouds at differing levels, so it's not always a viable option. <A> In a training environment, VFR-on-top is fantastic. <S> You can use your IFR clearance to punch through a cloud layer to clear skies on top, practice maneuvers (or what have you), and then shoot an approach back down.
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VFR-on-top can turn a bad weather day into a training day, and anytime you can do that (and get real-world actual instrument experience on top of it) is a good day. With this clearance the pilot can fly any altitude they want within this block of altitudes without having to contact ATC for further clearance.
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What is the name of the maximum altitude at which a helicopter can fly? What is the name of the maximum altitude at which a helicopter can fly? I recall it as "vertical limit", but I can't find a Wikipedia page for it other than a movie of the same title, which seems to concern mountain climbing altitudes. <Q> Usually two ceilings are distinguished; service ceiling , where the aircraft can still achieve a positive rate of climb of either 100 fpm (propeller) or 500 fpm (jet). <S> absolute ceiling , the theoretical altitude at which no positive rate of climb can be achieved. <S> In other words: the maximum altitude at which the aircraft theoretically can fly under maximum engine power. <A> Helicopters also have a stat you might have seen called In Ground Effect (IGE) and Out of Ground Effect (OGE) <S> Hover altitudes. <S> This is the maximum altitude (MSL) <S> the helicopter can hover at when it is in or out of ground effect. <S> Essentially, when IGE, a helicopter can hover at higher Mean Sea Level (MSL) altitudes because they get a little help from the proximity of the ground, which reduces the rotor tip vortices (reduces the drag on the rotor). <S> This site has some good info on ground effect as it relates to helicopters. <A> Under 14 CFR Part 29.1527 , the Maximum operating altitude for a transport-category helicopter is: § 29.1527 <S> Maximum operating altitude. <S> The maximum altitude up to which operation is allowed, as limited by flight, structural, powerplant, functional, or equipment characteristics, must be established. <S> So its not just a matter of power or thrust, or even just retreating blade stall, but rather the entire design envelope for the helicopter must be taken into consideration for maximum altitude. <S> For example, the Robinson R-66 has a number of operating limitations that pertain to factors other than maximum thrust: <S> And there is a Vne chart which limits forward speed to prevent retreating blade stall at high density altitude:
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Like with fixed wing aircraft, it is called the ceiling .
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What's the purpose of partial autopilot disengagement after applying certain force to the control wheel? Aeroflot Flight 593 crashed after the autopilot was partially disabled by applying certain force to the control wheel but the only function which was disabled was controlling the ailerons. This partial disengagement went unnoticed for a number of reasons. I'm reviewing the official accident report (text is in Russian, linked to from the Wikipedia article) and here're my findings from there so far. The flight manual (cited in the report) is claimed to say that manipulating the control wheel to contradict the autopilot is definitely abnormal and should be avoided. The mechanism for overriding the autopilot is a safety device that engages outside normal operational conditions. So it looks like there some functionality that allows to override the autopilot and partially disconnect it (so that only ailerons are no longer controlled) and it is claimed to be a safety measure. What's the purpose of this functionality? <Q> On Boeing planes, the controls will physically move along with the autopilot. <S> If the plane starts doing something you don't want it to do, the instinctive action is to grab the controls to correct it. <S> While the autopilot button would normally be the way to disconnect the autopilot, it may not be the instinctive way in an emergency, and it can be helpful to already have both hands on the controls when the autopilot disconnects, rather than having one hand disconnecting the autopilot. <S> The reason for only disconnecting one part of the autopilot could be to help the pilot. <S> Maybe there is a problem with the elevator controls, or an upset that affects the aircraft primarily in pitch. <S> Maybe the TCAS gives a "climb" command. <S> The pilot wants to take over pitch control to address this situation, but other controls are fine. <S> While the pilot now has control of just pitch, the autopilot is still taking care of the other controls. <S> The autopilot only gives the pilot control of the modes that are being overridden, instead of just turning off and requiring the pilot to deal with all control modes. <A> Although it doesn't address partial disengagement, this SB gives the reasons why forces on control columns could be used to disengage the autopilot. <S> Airbus Service Bulletin (sb) <S> No. <S> A300-22-6021 says 2) <S> Objective/Action To provide autopilot disengagement by applying a 15 daN force on the control column in go-around mode above 400 feet (radio altitude) <S> this Service Bulletin recommends to modify the software at both flight control Computers. <S> The modified Flight Control Computers will also include improvements which have been identified from the last standard. <S> (3). <S> Advantages Operational benefit and/or passenger comfort by : autopilot disengagement by 15 daN force on control column during go-around above 400 feet (radio altitude), avoidance of unwanted atopilot disengagement when the pilot takes firmly the control column, nose dowm improvement to avoid the pitch attitude increase after main landing gear touch down, improvement of "LEVEL CHANGE" mode; to avoid the "VMO" overshoot, "ALT HOLD" mode improvement in heavy turbulence. <S> improvement of autopilot capacity to counteract strong vertical gust in cruise. <S> n.b. 15 daN = 15 <S> deca-Newtons = <S> 150 Newtons = <S> ~34 lbs. <A> The reason for this kind of functionality is that if you are handling the controls with that much force, the autopilot assumes you want to fly and gets out of the way. <S> The forces needed to do this typically are not the kind produced by incidental contact but rather from purposeful contact. <S> In the planes I'm familiar with the aural warning system will start announcing "AUTOPILOT" until you hit a button to silence it. <S> In addition, the autopilot annunciation area will indicate the change in autopilot mode or disconnect. <S> These indications should be monitored at all times the autopilot is flying and the chain of errors here is: inadvertent autopilot disconnection (partial), and failure to properly monitor the airplane.
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The autopilot will disconnect on large control inputs because this is the most intuitive way to control the plane.
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Has Airbus planned to build a larger version of the A380? The current Airbus A380-800 could carry over 800 people. Has Airbus planned to build a new, larger version that could carry 1000 or more passengers? <Q> Has Airbus planned to build a larger version of the A380? <S> Yes, <S> In 2012 they planned to build a larger version of the A380. <S> "Airbus says 1,000 seat A380 due 2020" <S> However, manufacturers do change plans from time to time, sometimes in response to market conditions. <S> "Has planned" is not necessarily the same as "is planning" . <S> Those plans are not currently (8 Jan 2015) being pursued and consequently, as time goes by without a resumption of those plans, it is increasingly likely that any target dates in those plans may no longer be attained. <S> If you want to know do Airbus in January 2015 have active plans to build a larger version of the A380 - that would be a new question. <A> The answer is clearly yes : The ratio of wingspan to fuselage length is unusually large for modern transport aircraft. <S> The A380 has a wingspan of almost 80m and a fuselage length of less than 73m, whereas in other modern transport aircraft the fuselage is longer than the wingspan is wide. <S> Airbus designed the A380 with lots of stretch potential. <S> With the cooperation of engine manufacturers, the A380 may one day have a fuselage length of around 100m. <S> This is greater than the maximum length of 80m used in current airport layouts, but Airbus is betting on operators to urge airports to accomodate a stretched A380, just like they did for the current model's wingspan, weight and height . <S> The A380 will be the biggest Airbus for the next 30 or maybe even 50 years, so it better offers some growth potential. <A> Demand for the A380 has been soft, leading Airbus' own CFO to suggest to investors last month that the A380 might be discontinued entirely unless they can find enough customers willing to buy a re-engined version of it soon. <S> Orders for large, quad-engine airliners, including the A380, have been light lately. <S> Since taking the first order 14 years ago and over 7 years since the first delivery, only 318 A380s have been ordered , nearly half of which were from Emirates, and many of the A380's orders will likely be cancelled . <S> While the Boeing 747 has had over 1,500 deliveries over its long lifespan, it, too, currently has a small order book with only 16 net new orders since 2008 . <S> In contrast, twin-engine wide-bodies have been selling very well lately. <S> The A350 just delivered its first aircraft and already has 778 orders . <S> Similarly, the first 787 was delivered a little over 3 years ago and it has 1,055 total orders , so far. <S> The 777X, currently scheduled for production in 2020, was first offered for order a little over a year ago and already has 286 orders . <S> Total 777 orders so far <S> number a whooping 1,807 . <S> The long-haul wide-body market has been trending very strongly towards twin-engine aircraft like the 777, A330, 787, and A350 lately rather than mammoth quad-engine aircraft like the 747 and A380. <S> As such, it seems unlikely that Airbus is going to be sinking billions of dollars into a stretched A380 any time soon. <A> Actually I think they don´t have any plans for a stretched version of A380. <S> Tim Clark, CEO of Emirates, wants a larger A380 but Airbus said (last time when this topic came up) that they would rather improve the current A380 and increase the performance. <S> They are making a change by increase the lower floor height to add extra seat in each rowon economy <S> but thats it. <S> Now Tim Clark is pressuring to make a neo-version af A380 and and Airbus is consideringthat option. <S> Emirates say that they would order up to 70 A380neo if that plane will be launched but Airbus has to calculate the cost and if it´s will be profitable for them. <A> Yes, and in the short-term they're also talking about re-engining the existing A380 with engines based on those on the A320neo as outlined here .
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Airbus has certainly made preliminary plans for a stretched version of the A380 ( the A380-900 ,) but no plans currently exist for that model to go into production.
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How often is communication lost with aircraft? I just read the NTSB press release of Northwest Airlines Flight 188 that flew more than one hour without making any radio contact. I imagine there may be many causes for losing radio contact with the ground (distraction, electrical failure,...) and I found a video (in French) saying that one way to solve the situation is to send a fighter to have a closer view of the situation and possibly assist the pilots. I wonder if the situation of losing contact with an airplane is frequent? I imagine it happens between one and ten times per month over a region as big as the USA, but that is just a guess. <Q> According to this FAA paper , Table 3, ASRS reports were analyzed for 16 months between 1978 and 1979. <S> This included 553 incidents where the recipient was not monitoring, which seems to be the closest category to loss of communications. <S> This equates to a little more than 1 incident a day. <S> Note that this only includes incidents that were reported, and air traffic has increased since then. <S> This report contains info from ICAO in in Europe. <S> The focus is on the security issues from unresponsive aircraft. <S> In just the northern region, there were 230 flights over just 6 months in the beginning of 2004. <S> This number inclues airlines, business jets, and military transports. <S> This frequency is a little higher than the previous report, but is more recent and probably includes less flights. <S> Other reports like this one <S> don't include a time frame for the reports analyzed, but look at other factors involved. <S> For example, pilots with fewer hours and GA pilots are more likely to be involved in such an incident. <S> The average duration of these incidents was 7.6 minutes. <S> This page also has some good information about this type of incident, including a list of some of the many possible reasons for lost communications and excerpts from some of the reports. <A> I think it happens all the time actually. <S> Most of the time its likely not reported. <S> When I did my first solo cross country in a 152, my radio button went out while using VFR flight following. <S> Perhaps they did report it, but they likely just thought it was a new pilot not knowing what he was doing. <S> It was really distracting for myself at the time as a pilot in training. <S> I could hear them talking about me and it took a while to understand that they were not hearing my responses. <S> As a pilot, you are supposed to squawk 7600 to let them know you lost your radio. <S> At the time though, I couldn't remember if it was 7500 or 7600. <S> I knew one of them was for the radio and the other was for a highjacking, and I wasn't needing a fighter jet for my broken radio. <A> I think losing contact for an hour is unusual, but not being in contact with ATC for a few minutes is pretty common. <S> On a cross the US flight you might hear 5-6 incidents. <S> Most of these seem to occur as planes are handed off from different sectors that use different frequencies. <S> It not uncommon for the pilot to tune in the incorrect frequency. <S> Also, as aircraft descend into fields with obstacles (ex. mountains) <S> it is not unusual to lose contact. <S> As you fly along you sometime hear ATC attempting to contact a plane and get no reply. <S> If you have just heard that call sign you might volunteer to give the aircraft a call and then act as a relay. <S> For example, you are over some place and hear ATC: "KingAir 123 contact center on 123.55"KA123: no response. <S> ATC: "KingAir 123 contact center on 123.55"KA123: <S> no response. <S> ATC: "KingAir 123 over someplace contact center on 123.55"You: "Center, N12345 <S> , we are over someplace, would like us to try to contact KA 123?"ATC Center: "N12345, affirmative, contact KingAir 123 and ask them contact center on 123.55"You: " <S> KingAir 123, N12345, center would like you to contact them on 123.55"KA123: "Contact Center 123.55, thanks N12345" <A> Sometimes the plane "lost" the frequency, and showed up elsewhere. <S> Sometimes they had an equipment failure. <S> On nice weekends, they have more, and those are written off as VFR pilot error situations. <S> While we were talking, I asked how many 7600 squawks they got per month, and he said somewhere between 0 and 2. <S> More common during the summer when more people are flying, and during the hard part of winter when there are just more equipment failures. <S> Not a big study, but just one ATC supervisor's opinion and observation. <S> As for looking at 1970 and 1980 data, the whole business of radios, and how well they work has changed quite a bit in 20 years. <S> I can remember radios being out as much as 1/3 of the time <S> (well one or the other most of the time) back in the 70's. <S> Today it rarely happens. <S> For one thing, the radios today don't have the large ganged switches that the older radios had. <S> And the avionics guys say that today's transponders are more stable, and last longer as well.
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A supervisor at the local ATC facility (medium sized TRACON/Tower) said they have loss of radio several times a month.
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Where do all the bullets end up? When planes engage with guns, many of the shots are misses... what happens to the bullets? Do they kill people on the ground and damage facilities? Do we have any records of this happening? <Q> Do they kill people on the ground? <S> Almost certainly a few do. <S> People struck by falling bullets are more likely to die than people shot directly. <S> The chances of a particular bullet falling onto a person are very small but over the decades, many many bullets have been fired by aircraft. <S> Handgun bullets <S> Between the years 1985 and 1992, doctors at the King/Drew Medical Center in Los Angeles, California, treated some 118 people for random falling-bullet injuries. <S> Thirty-eight of them died. <S> Bullets fired into the air during celebrations return at a speed fast enough to penetrate the skin and cause internal damage to other organs in the path of the migrating bullet. <S> The bullet’s velocity required for skin penetration is between 148 and 197 feet per second. <S> A velocity of less than 200 feet per second, which is easily obtained by a celebratory gunfire, is capable of fracturing bone and even causing intracranial penetration [4]. <S> Spent bullets have the capability of reaching up to 600 feet per second during their downfall, and thus they have the ability to inflict damage to multiple body cavities [4]. <S> The larger caliber bullets (ie, .45-caliber) reach a higher terminal velocity compared with the smaller caliber bullets (ie, .30-caliber), because of the proportion of their weight to their diameter [4]. <S> From http://www.annalsthoracicsurgery.org/article/S0003-4975(06)00831-9/abstract <S> For those hit by falling bullets, the chance of the wound being fatal was far higher than a typical shooting. <S> The hospital put deaths from regular shootings between 2% and 6%, while for those struck by falling bullets the death rate was close to one third. <S> From http://www.theguardian.com/world/2011/aug/24/how-dangerous-is-celebratory-gunfire Aircraft rounds <S> These falling bullets were from celebratory gunfire, not fired from aircraft. <S> Aircraft cannon fire projectiles which are often much heavier than handgun rounds. <S> If one falls on you, the likelihood of injury or death must be higher. <S> .22 <S> Winchester magnum rimfire and .50 <S> Browning MG rounds at same scale. <S> source <A> Falling bullets are similar to falling stones, albeit with higher density and higher terminal velocity. <S> Small ones won't do much damage, but I don't want to be hit by one from a 37mm cannon. <S> Same goes for shrapnel: Flak/AA-guns could not fire steeper than approx. <S> 85° to prevent the gun crews to be hit by their own shrapnel. <S> One airplane became famous (at least in pilot's folklore) for the ability to shoot itself down. <S> According to that rumor, the Republic F-105 could outrun its own bullets in a shallow dive at supersonic speed. <S> When the bullets, having been fired in horizontal flight, slowed down due to aerodynamic friction and went down in the usual parabola, an accelerating, diving plane could catch up with the bullets. <S> The relative speed between both would be small, however, so the kinetic energy would cause less damage than bullets straight from a gun. <A> They can kill people or cause property damage. <S> They probably won't. <S> It won't continue at the speed that it was when it was shot. <S> The same problem occurs with celebratory gunfire. <S> If you're shooting at an angle less than 40 degrees, that can prove very dangerous. <S> But straight up in the air, it probably won't be going fast enough on the way down to hurt a normal person. <A> You are not the first person to worry about this. <S> In the 1942 war movie <S> Mrs. Miniver <S> a principal character is killed by stray bullets from an aerial dogfight. <S> This was considered quite realistic as rounds fired in a low-altitude dogfight often had plenty of kinetic energy when they hit the ground.
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If the plane is at sufficient altitude and shoots a bullet straight down, the bullet will encounter enough air resistance to slow to terminal velocity.
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What radios are airliners / large aircraft equipped with? I know that pilots have to talk to the tower over the radio, and apparently you have to tune the radio to the right tower frequency. I've also heard that in an emergency, you're supposed to "squawk 7700." Presumably you're not just making bird noises with your mouth, but some sort of radio code. Are these the same radio system? What radio communication systems are modern big jets equipped with? <Q> Numbering the radios that I can think of offhand in the old 747-100 and -200 aircraft that I used to fly produces: 2 VHF voice communications radios. <S> 2 VHF navigation radio receivers for receiving VOR and LOC signals. <S> The LOC frequencies are paired with UHF frequencies for receiving glideslope signals. <S> 1 ADF (automatic direction finding) receiver. <S> 1 HF (high frequency) voice communication radio. <S> 2 transponders to send whatever the "squawk" is when interrogated. <S> #1 was used on odd days of the month, #2 on even days. <S> There are a number of standard codes, but ATC assigns a 4-digit code to each aircraft during flight under their control. <S> There is never an 8 or a 9 in the code because it's an octal code. <S> 1 SELCAL (selective calling) receiver, which will sound an alert if it receives a signal sent by a ground station. <S> It may not be a separate radio but just a box listening for a tone on one of the voice communication radios. <S> 1 weather radar, and, yes, radar is a radio (radio detection and ranging) employing both a transmitter and a receiver. <S> 1 radar altimeter for use in the final stages of the landing approach. <S> Some were "talkers" in that starting around 50 feet, they would announce your altitude in increments of 10 feet. <S> 1 GPWS (ground proximity warning system). <S> I'm not sure whether it and the radar altimeter shared a box/circuitry <S> /antenaes. <S> 1 GPS receiver, which we got only in the last few months before I retired in 1999 <S> 1 ELT (emergency locator transmitter) life raft locator beacons. <S> I can't remember how many life rafts there were. <S> life raft voice communication on 121.5 and maybe 243.0. <S> I may not have remembered them all. <S> Modern transport category aircraft would also have SATCOM. <S> Military aircraft would have UHF voice communications and mission appropriate weaponry radios. <A> This site has good information about the various radios on the 737 classic vs. NG, which will be similar to other modern airliners (though locations may differ somewhat). <S> The graphics at the bottom show the external antennas, which include (for the NG): <S> Glide Slope - for ILS guidance Localizer - for ILS guidance <S> Weather Radar <S> GPS Radio <S> Altimeter <S> ADF 1 - Navigation <S> ADF 2 Marker Beacon - for approach guidance <S> DME - Navigation <S> VOR - Navigation <S> TCAS x2 <S> ATC <S> 1 - Maybe transponder, ACARS ATC 2 <S> VHF 1 - Regular voice communication VHF 2 <S> HF - For long range voice communication, such as oceanic crossings <S> ELT - Emergency Locator Transmittor Please note that the above location diagrams are only a guide as the antenna fitted <S> depends upon the customer avionics options. <S> Eg some NG's do not have ADF but do have SATCOM or IFTS/Airphone. <S> More and more planes have satellite antennas for in-flight internet access, too. <S> Military planes will also include more antennas for things like UHF and SATCOM. <S> Another site offers some details about certain radios on the 737 NG, including the power each one uses: HF Voice Transceiver 400WVHF <S> Voice Transceiver 25WDME (962 to 1150 MHz <S> Xmit) <S> 316WRadar <S> Altimeter (4300 MHz) <S> 400mWTCAS 400WTransponder (1090 MHz) <S> 631WWX Radar (9.3 Ghz) 120W <S> For instance, it's interesting how the HF radio uses much more power than the VHF radio, and that the transponder uses the most power on the list. <A> "Squawking" in this sense refers to punching a number into your transponder: http://en.wikipedia.org/wiki/Transponder_(aeronautics) <S> There are some squawk codes on that page if you want to read more!
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This depends on the plane - some planes don't have radios at all!
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If AWOS reports IFR conditions but I can see at least three miles, can I take off or land? The uncontrolled airfield where I have my airplane gets foggy in the morning occasionally, but there have been times when there is just a little fog where the AWOS station sits so it reports 1/4 mile visibility and undetermined ceiling, yet the runway farthest from it is clear and there are no clouds. My flight instructor and ground school instructor said you must always comply with the AWOS reported conditions, yet my flight examiner (I just got my private pilot license) said a pilot can overrule the automated station if it is clearly wrong. Machines can break and are limited to where their position is.FAR 91.155 talks about visibility, but doesn't mention how it is determined. Flight visibility is determined by the pilot, so I interpret this to mean he can overrule the AWOS if it is clearly wrong. (d) Except as provided in §91.157 of this part, no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport— (1) Unless ground visibility at that airport is at least 3 statute miles; or (2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles. (e) For the purpose of this section, an aircraft operating at the base altitude of a Class E airspace area is considered to be within the airspace directly below that area. Another question about (e), after reading it about 5 times: my airport is class G up to 700 feet, then turns into class E above that. Does (e) mean that if I am at 700 feet AGL, I am still in class G? Of what significance is this? <Q> In the specific case that you mentioned (VFR at an uncontrolled field), you can take off or land because the only legal requirement is to maintain VFR cloud clearance <S> and it's your responsibility at the pilot to do that. <S> The possible downside would be that if you have some kind of accident or incident and the FAA or NTSB investigates, they will take the AWOS reports as the reference for weather conditions at the time. <S> If weather or visibility was relevant to the accident then your decision might be questioned, unless of course there are witnesses who can confirm the actual conditions. <S> In the case of a controlled field and VFR, ATC will base their actions on the reported conditions so they would tell you that the field is IFR only. <S> One 'workaround' that could be useful is an SVFR clearance, which allows you to operate VFR in an airport surface area even below VFR minimums. <S> You have to request it because ATC can't offer it although they may hint strongly at it to help you out: "the field is IFR, is there anything you'd like to request? <S> " <S> But ATC may not issue an SVFR clearance if the reported visibility is below 1 mile , so <S> in the scenario you mentioned it wouldn't help you. <S> (And note that you need an instrument rating for SVFR at night.) <S> Under IFR the picture is different. <S> Legal in this case obviously isn't the same thing as safe, though. <S> I deliberately didn't answer your second question because I think it would be best for you to submit it as a separate question. <A> According to AIM 5-5-1 paragraph b: <S> The pilot-in-command of an aircraft is directly responsible for, and is the final authority as to the safe operation of that aircraft. <S> CFR Section 91.3(a) states: <S> The pilot-in-command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft. <S> You'll see this pattern throughout the FAR/AIM's. <S> The regulations state what parameters you can operate under, but you're responsible for gathering data from METAR's, TAF's, ASOS and ATIS and other sources and making a decision on weather you are able to comply with VFR weather minima for the class of airspace <S> you're in if you depart. <S> Regarding your second question: The floor of E is at 700ft so that means if your altitude is 700ft AGL exactly you're still in E <S> but you're subject to the weather minimums of whatever is below it which in your case is class G weather minimums. <S> If the floor of the class E was on top of Bravo airspace, then if you're exactly on the floor you're subject to class B weather minimums. <S> I think it's just anticipating the lawsuit that may arise from someone being exactly at 700ft and claiming they were in class E instead of whatever is below it with regards to weather minimums. <A> Read 91.157: <S> (d) <S> "The determination of visibility by a pilot in accordance with paragraph (c)(2) of this section is not an official weather report or an official ground visibility report." <S> Even though this is in 157 not 155, I think that if you were involved in a weather-related incident, the FAA would argue that the OFFICIAL reported weather controls, not the pilots judgment. <S> This is probably what the Instructor means. <S> However, many uncontrolled fields, such as yours, have non-official automated reporting, which you could argue is advisory and not regulatory. <S> This is probably what the Examiner means.
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A part 91 IFR flight can legally depart in zero visibility so there would be no issue there, provided that you get your clearance on the ground first, before entering IMC.
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Which hand do fighter pilots use for the control stick? Here is a question that has been bothering me for a while. Do right-handed fighter pilots use their right hand to hold the control stick? And do left-handed fighter pilots use their left hand? Or is it the other way around? Or do they maybe use both hands a lot of the time? It also brings up the question as to what the other hand is expected to do and which side of the cockpit the most common control buttons are on. My guess is that since most people are right handed, they use their right hand. There's also triggers on the yoke so it seems all the more likely that the right hand is used for right-handers. I'm asking because you look at video games and their controllers . They always use the left joystick for moving the character. In the case of flight simulators, the left joystick is used as the 'stick' or yoke. So you're pretty much left with no choice but to use your left thumb. Not saying this is awkward for video games, however, on those big joysticks for PC games, I remember I always used my right hand. Also, let's ignore civil commercial piloting because those seem to usually use steering wheel type controls, not a traditional stick. Please let me know if you're a fighter pilot when you answer, because the triggers on the yoke have an effect on which hand you're most comfortable with. <Q> Most fighter pilots, regardless of their handedness, use their right hand to fly the stick, and their left hand to move the throttle(s)/PCL <S> (Power Control Lever). <S> This is just how most fighter cockpits are set up, with the power on the left side. <S> The sticks are also not really usable for a left hander because a few of the buttons would be inaccessible with a left hand on the stick. <S> In some cases (like the F-16), the cockpit uses a sidestick layout, with the stick on the edge of the cockpit, rather than in between the pilot's legs. <S> So no, it would not really be possible for left-handed pilots to fly with their left hand on the stick for long periods of time (I will note, that if you need to select something on the right side, most will hold the stick lightly in their left hand for a brief second, actuate the item with their right hand, and then switch back) unless the entire cockpit were redesigned, which is just not worth it. <S> (I am not a fighter pilot, but I have flown military trainer aircraft that have the same general layout as an actual fighter, and I also know several fighter pilots) <A> I am an ex-military pilot and retired airline pilot who is still an active pilot in general aviation. <S> The simple answer is that single seat and tandem seat cockpits are set up with the throttle and trim on the left, so that the stick has to be handled with the right hand. <S> I never have trouble switching back and forth, but some people do. <A> Its not just fighter planes that have the stick in the right and power in the left. <S> That's the way tandem (front-and-back seating) aircraft are set up in general. <S> You can see the throttle on the left-hand wall in this Citabria: <S> And gliders and helicopters are also set up with "the stick" in the right hand and "power" in the left. <S> Even though a glider doesn't have an engine, most of them have some kind of airbrakes, which are deployed just as if it was a throttle. <S> Pushing the lever forward with the left hand decreases drag and pulling backwards increases drag. <S> This isn't the same as thrust, but to a power pilot, it feels fairly natural to push forward to go faster and pull backwards to go slower. <S> The speed brake handle in this glider is the blue handle on the left. <S> In a helicopter, the right hand (no matter which side the pilot sits on) is for the cyclic, which (for the post part) controls pitch and roll, and the left hand controls the collective and throttle, which together work to add and remove power from the aircraft. <S> This also feels fairly natural to pilots who are used to stick in the right, throttle in the left. <S> The big difference is that the collective is an "up/down" control like a Johnson bar , not a "forward/back" control, and you put it down to reduce power and up to increase power. <S> Furthermore, the throttle, when manually controlled, is a twist grip on the collective, which operates more like a motorcycle throttle. <S> You can see the heli controls in this simulator.
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With a few exceptions side by side cockpits have wheels and the throttle and trim are between the seats so that the pilot in the left seat, usually the pilot in command, uses his left hand on the wheel and the other pilot uses his right hand on the wheel.
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Is it possible to go-around at Lukla Airport? On this airport , it seems the runway end with a wall followed by a mountains . Thus the pilots physically can't overrun the runway and if they decide to interrupt the landing, the go-around maneuver seems to include a very tight turn to avoid the mountain unless performed very soon during the approach. Is it possible to perform a go-around, and a which point it becomes impossible for this particular airport? <Q> No, it is almost impossible. <S> The only runway (06/24) <S> Lukla Airport is just 1500 feet long. <S> This article lists some interesting facts: <S> At the south, the runway is the end of an angled drop of about 2000 feet. <S> This cliff is fenced off as a precautionary measure. <S> At the northern end of the runway there is a huge mountain terrain. <S> It leaves no room for error. <S> A pilot mentions the same here : <S> "Because there is no way to go around again, we have to calculate many things like air speed, tail wind, fog. <S> If you don't do the proper calculation or proper exercise, then it (an accident) happens." <S> Planes land on runway 06 (Heading 060 or ENE) and takeoff from runway 24 (Heading 240 or WSW). <S> This picture shows the cliff on North: <S> There have been several accidents at this airport. <A> Hi guys few days ago a twin otter did make an aborted landing and made a "go around" at the airport and headed back to Kathmandu. <S> This is the first time such an incident happened although there has been numerous crashes in the past. <S> Here is a link to the video. <A> If you do a search on youtube you will find several video on go arounds at this airport, so I think go arounds are more common than some of the respondents above indicate. <A> You can not go around at Lukla, but if you try super hard, with a bit of luck, you might be able to turn back. <S> But it wouldn't look like a normal go around. <S> The reason for this is because Lukla is right in front of a huge mountain, And you won't have enough speed to climb fast enough.
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The topography of the place makes any go-around impossible.
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What determines in which direction a runway is used? A nearby airport has a single 05/23 runway (3900m long), where airplanes start and land in one direction during certain periods and in the opposite direction during other periods. How is the direction determined -- I assume it's air traffic control which decides that but based on what ? (wind, sun ?) <Q> There are several factors: <S> Prevailing winds <S> Neighboring airport traffic patterns Size of inbound aircraft <S> Where the aircraft is coming from Final parking space Congestion Fuel status Weather (thunderstorms) Noise considerations <S> At small airports, it is usually just the runway that faces into the wind and can accommodate most of the traffic coming in. <S> At large airports, the wind dictates which flow is being used (like a "north flow" or "south flow"). <S> From there, aircraft usually are assigned to land on which ever side of the airport their arrival procedure brings them to. <S> Sometimes, it is also decided by which gate/terminal they'll be parking at. <S> Lastly, the available approach procedures can change things if the weather is not good <A> Wind direction mostly, planes take off best when facing in the wind as that means free airspeed <S> so the takeoff roll is shorter. <S> In busier airspace (with multiple towered airports) each airport coordinates the corridors so they don't intersect depending on available runways, prevailing winds and relative demands on the airports. <S> It is possible that it is dictated by noise abatement measures so night time flights pass over a nearby forest rather than wake up the capital. <A> In some cases, when the wind is calm, airports have a default runway (it usually has better lighting, or approach systems for aircraft to use during conditions with poor visibility). <A> Most aircraft have a max tailwind limitation (those I've flown had a limit of 10 knots). <S> So for convenience, a pilot could take off with up to that 10 know tailwind, but not with a stronger tailwind. <S> Depending on runway length, and aircraft gross weight, it might not be possible to takeoff with the full max tailwind, necessitating a takeoff into the wind anyway. <S> Some runways are backed up against hills or mountains, and aren't safe to takeoff in that direction, so always land toward and takeoff away from the rising terrain.
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Runway in use is based on wind, most of the time, with aircraft taking off into the wind.
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How do you compare private jet and commercial jet efficiency? I'm curious about commercial airplane efficiency vs private jet efficiency. I was trying to compare something like a modern 737 flying a full commercial flight from NYC to LA vs an Embraer Phenom 300 at full capacity (8 people) flying the same route. I know there are many variations of the 737, so can we just use the most common commercially flown 737? If fuel costs were the same (I understand that big airlines get discounts) is there a simple way to compare the flights simply in terms of cost of the flight, or how much fuel each plane would need for the flight? I didn't want to get into profit, crew, etc. Simply the cost of flying both planes from NYC to LA. Thanks for any help. <Q> This has nothing to do with private vs. commercial. <S> The size difference is what matters. <S> If you compare the absolute cost of moving the aircraft from NYC to LA, the 737 will be way more expensive, regardless of version. <S> Since you asked only which one is more expensive, I don't see a need for detailed reasoning. <S> Just use the data provided in this answer <S> and it becomes obvious that fuel consumption will scale with the mass of the aircraft. <S> If all passengers have to share the cost, the cost per passenger will be much higher in case of the Phenom 300. <S> Or almost any other Bizjet. <S> The Phenom will even need to land somewhere enroute to refuel. <S> The distance from NYC to LA is bigger than the maximum range with full payload . <S> But that kind of comparison does not make sense - both airplanes have been designed for different purposes, so their strengths are in their unique field of use. <S> They do not transfer well to that of different aircraft types. <A> Hourly fuel costs for a private jet can run from 800-2000/hr USD. <S> So the 5 hours from NY-LA range from 4,000 to 10,000. <S> But fuel is only part of the equation. <S> On also has to figure in cost of ownership issues such as parking/hangar, insurance, engine reserves, avionics reserves, annual inspection reserve, etc. <S> Also there are additional direct operating costs such as pilot salaries, crew salaries, tied down/gate fees. <S> For some fractional ownership programs where all of this is loaded it is not uncommon to end up with a 4,000-8,000/hr figure. <S> This assumes you have already made a fractional payment of around 200,000-500,000 depending upon type of plane and percentage of ownership share (1/6, 1/12, ...). <S> There are also other programs where you rent the jet, crew, etc, but I have not looked at those figures. <A> Simply the cost of flying both planes from NYC to LA <S> The 737 will cost a lot more than the 8-seat bizjet. <S> Crew and maintenance are inescapable costs so excluding them <S> makes the calculations even more skewed. <S> Landing fees are based on gross weight class divided into the number of passengers, facility fees are actual number of passengers on board, parking is by size, navigation is based on ability-to-pay (the 737 pays, because it's a commercial flight. <S> A privately owned Cessna gets ATC for free). <S> The bizjet can use smaller airfields that can be hours closer to the group's destination so once you factor in ground transportation (and lower airport fees) and employee time the bizjet can actually work out cheaper per seat than Delta. <S> But you do have to consider everything. <A> I just found this list of various plane models and information about them such as average fuel burn and total variable cost/hour. <S> If anyone is interested: http://www.duncanaviation.aero/files/aircraft_sales/Business-Jet-Model-Market-Summary.pdf
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This kind of comparison is just about useless - direct cost per seat-kilometer is as basic as you can get, and even that one is very rough.
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How do big planes like 737 manage fresh air for passengers during flight? How do the big planes (e.g. A380 or 737) flying on high altitudes manage to get fresh air for passengers and crew during the flight? I know the inner space of the plane used for passengers and crew is sealed and the pressure is maintained within some range. However in standard flight altitude of about 10-14 km there is not enough oxygen to breathe. I am not sure whether the standard oxygen ratio is still about 21% and you only have less air (lower pressure). We talked two possible solutions and maybe I am still wrong: using some pumps and small pressure tanks to suck in air from outside till we get higher pressure and then use some valves to "replace" the breathed up air with the fresh one use some pressure tanks loaded with oxygen + some cleaning devices to clean the air and add oxygen to keep the same oxygen level - but this would need to get the oxygen before take-off and such tanks would be really dangerous So how is it in reality? <Q> They bleed hot compressed air from inside the jet engines, cool it down and pass it into the cabin. <S> There are outlet valves in the fuselage that allow stale air out and which control cabin pressure and air-refresh rates. <S> They do this because it can be more fuel-efficient (not for any other reason). <S> It is arguable whether it creates an additional fire hazard. <S> See also <S> Why is the compressed air (from Engine Compressors) taken from High Pressure (HP) stage instead of Low Pressure (LP) stage <S> Can an aircraft re-pressurize at high altitude? <S> Is constant air pressure maintained inside the fuselage? <A> Airplanes basically draw in outside air, compress it, and send it to the cabin. <S> RedGrittyBrick lists some related questions about this process. <S> Most airplanes use bleed air from the engines, using the compressors in the engines to do the compressing. <S> Although in normal operation this will only bring in outside air, engine issues can cause fumes to enter the cabin . <S> The 787 uses an electric compressor that draws from separate intakes. <S> The problem with breathing at high altitudes is not necessarily the lack of oxygen, but the low pressure. <S> Humans need a certain partial pressure of oxygen for the lungs to work properly, and as pressures drop, the oxygen is less effective at getting into the bloodstream, which results in hypoxia . <S> So keeping the cabin pressurized is what allows the occupants to breathe normally. <S> For more information about the cabin environment, see this paper . <S> Ventilation can be expressed in "outside air changes/hour", or how often the total volume of air is replaced by new air. <S> Airplanes have 10-15 changes/hour (every 4-6 minutes), which is 2-3 times more changes/hour than hospital delivery and operating rooms, and 4-15 times more than a typical building. <S> New air is constantly being circulated into the cabin, while old air escapes through relief valves. <A> Bleed air from the engine is used to power a Pneumatic Air Cycle Kit (PACK) which takes in outside air heats it and compresses it. <S> The mechanism is entirely mechanical using turbines and heat exchangers and engine bleed air is isolated from the air destined to the cabin to avoid oils and fumes entering the cabin. <S> The answer to How hot would pressurized air get if the air conditioning failed? <S> ex^plained in detail how a PACK works.
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A few aircraft types, such as the 787, now use a compressor to take in air from under the aircraft.
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Is it possible to recover dumped fuel? During emergencies pilots are authorised to dump fuel, but is there any way or method to recover the fuel that has been jettisoned? <Q> In practical terms, no. <S> If you wanted to save/recover the dumped fuel then you would have only two basic options: dump the fuel as usual and then recover it somehow from the air; or, pump the fuel in a controlled way into a container outside the aircraft. <S> The first option is probably impossible: how could you capture a huge cloud of fuel and fuel vapor mixed with the air? <S> That would be like gathering water from clouds. <S> The second is theoretically possible, but for civil aviation at least it probably requires too much equipment and risk. <S> You could pump the fuel into a drop tank then jettison it with a parachute for a soft landing. <S> Or you could pump the fuel into another aircraft via a tube, in a kind of reverse air-to-air refuelling. <S> Or if you're dumping fuel from a helicopter (does that ever happen?) <S> it could hover over a tank on the ground, pump out the fuel and then land. <S> But all of those suggestions are totally impractical (again, at least for civil aviation). <S> Adding drop tanks or air-to-air hoses would add huge cost in materials and training and reduce the useful load of the aircraft significantly, all for a situation that rarely occurs. <S> And for air-to-air pumping you would need an empty tanker aircraft to be available immediately, which is highly unlikely, plus there is the inherent danger of operating two aircraft very close together. <S> Since fuel dumping is an exceptional situation and many aircraft <S> can't dump fuel anyway <S> , it seems unlikely that investing in a recovery solution would be worthwhile. <A> In theory it could be done, you could rapidly dump fuel into empty tanks below the wings and drop them. <S> At a certain height they deploy Parachutes and land. <S> Just like the Space Shuttle ejects the side tanks. <S> But where? <S> Some fuel dumps are only authorized over water and it would cost more to rescue the tanks and bring them back to the airline. <S> Over land they'd probably smash into populated areas. <S> The cost for saving some thousands of $ of fuel is not fesable for the rescue. <S> Short answer <S> yeah <S> it could be possible, but dangerous and costly. <A> By conserve you mean collect for later use I am assuming. <S> While it is technically feasible to do that it is extremely impractical. <S> Any system to do this would require precision on the part of the aircraft needing to dump fuel, and in the kind of emergency where dumping fuel is required precision is one thing you aren't likely to get. <S> Also, the cost of implementing a collection system far outweighs the cost of the fuel you'd save. <A> I suppose the least expensive way to do it would be to reinforce the airplane structure so that it coud land at maximum takeoff weight. <S> Then no dumping would ever need to occur. <S> Still not cheap enough to be practical, though. <S> The weight of that extra structure would take fuel to carry around at all times, to save fuel only on the rare emergency. <A> The pilot can either keep circling around to burn it off (doesn't conserve it) or just land overweight without jettisoning. <S> Burning it off is not an option if you want to get on the ground now to deal with the emergency. <S> And landing overweight can create a new emergency if the gear collapses/too many tires blow.
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You'd have to either have another aircraft fly in formation in some sort of reverse in-air refueling system, or the pilots would need to fly over a system on the ground which would collect the fuel.
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Is this takeoff of a 767 in bad weather conditions a normal procedure? In this video , a 767 takes off in bad weather conditions. The comments of the video aren't very professional, so I ask here: Is this a legitimate takeoff? Some comments say that this was a close takeoff. Some comments do point out that on rotate, you can see the end of the strip of the lefter runway. Was it airborne before? <Q> Take-off within the crosswind limits is a normal procedure. <S> Rotation seems to be on the 1000ft marker, i.e. 1000 ft from the runway threshold. <S> But in case of a displaced threshold the take-off distance available may be more than 1000ft from that point. <S> It was airborne before the end of the runway. <A> Without having a better understanding of the actual crosswind there's no way to say whether that one was out of limits. <S> If I had to guess I'd say it was close. <S> I fly light aircraft, not commercial jets but as far as I know takeoff in a heavy crosswind is similar - <S> you keep aileron into the wind, and a bit of forward pressure on the stick to make sure your wheels have good contact to the ground. <S> During the roll you build up a bit of extra speed so when you are ready to rotate you get well off the ground quickly <S> so you get some ground clearance, and also have better control authority. <S> It looks to me that's what these pilots did. <S> Given the conditions it was never going to be a comfortable ride, I see nothing wrong with the take-off. <A> Assuming everything was within its limits since we can't prove otherwise and therefore a legitimate take-off, it's the captain's call whether to take-off or not. <S> Nevertheless, judging by the video, the precipitation seems far too severe to consider this take-off completely safe. <S> Also, the crosswind might have been quite strong considering the open spoilers (also called airbrakes) caused by full left aileron being applied to compensate for the crosswind, which ultimately increases the take-off distance. <S> Furthermore, if it was a stormy cumulonimbus cloud , the take-off could have been delayed by half an hour, and the meteorologic conditions would have been much better in terms of precipitation (and it would avoid scaring all the passengers). <S> From my point of view the main problem with such take-off would be in case of a take-off emergency (like an engine flame out due to the intensive water ingestion) before V1 , forcing the pilots to brake, risking a runway overrun due to hydroplaning. <S> They made it, but I don't think it was the smartest decision! <A> It looks like it was raining (a lot) with a pretty good crosswind. <S> They probably loaded extra fuel for the weather and decided to rotate after Vr instead of exactly at Vr, thus using more runway. <S> Wiggling the controls around didn't help the takeoff roll but it did keep the plane straight - usually a good thing. <S> As a passenger this would not have bothered me at all. <S> Some years ago I was departing Hong Kong on Northwest, right in the middle of a typhoon. <S> We sat at the threshold for 20-30 minutes, then the engines went to full power and we got out of there. <S> The FA across from me said the flight crew told them to buckle in and stay seated for 20 minutes after takeoff, and she'd never heard that in her career. <S> So obviously the pilot felt it was going to be a rough ride <S> but he also felt it would not be a problem. <S> Landing back at the airport in the video would have been quite exciting, possibly requiring the Force in addition to redundant Cat IIIb autoland. <S> But there's no requirement that you return to your departure airport if you have a problem - if there's another one 10 minutes away with better weather you go there instead.
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From the video it's hard to tell what the crosswind was in this particular situation, so it is impossible to tell about the legitimacy of this take-off.
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How is the cargo hold volume for passenger aircraft designed? An A380 has up to 2 decks for passengers and only 1 deck for cargo (for passenger's luggage), whereas a B777 has 1 deck for passengers and 1 deck for luggages. It looks like the volume of luggage per passenger is reduced in a A380 compared to a B777. Is that true? Is the volume of luggage per passenger the same? Is there a method to calculate the volume of the cargo and then to design its shape? <Q> The cargo compartments are not only for luggage. <S> Commercial cargo also travel on passenger aircraft, besides cargo aircraft. <S> With luggage alone, there are plenty of spaces in the cargo deck. <S> In fact, if you fill all the seats, all the cargo space and sufficient fuel for a long trip in a B777, the plane won't takeoff - its GW (Gross Weight) exceeds the MTOW (Max Take-Off Weight). <S> Airlines are smart people - if a flight is not full, dispatch will put more cargo on the aircraft to utilize it. <S> A lot of passenger airliners also offer air delivery service. <S> Some passengers complain, "I can't book the flight. <S> The staff says it's full, yet there are many empty seats!" <S> Commercial cargo yields more revenue than an economy seat. <S> Thus, given the weight limitation, an airline may prefer cargo vs passenger. <S> I don't have info about A380, but I'd guess that the A380 has less extra cargo space than the B777. <S> But as long as it's enough, it isn't a problem. <A> The cargo hold volume is a secondary result of the design process. <S> Pressurized fuselages need to be round for best structural efficiency, and the passenger compartment needs to be high enough for passengers to stand upright. <S> The rest has to follow from that, and the old narrow-body aircraft (like the DC-8 or the Boeing 707) were mostly volume-limited (which means that they would have benefited from more internal volume), whereas the early wide-bodied aircraft ( A300 , Boeing 747) are weight-limited (which means operators flew them with some volume unfilled to avoid overloading the plane). <S> The picture shows the fuselage cross section of an A310 (left) and a Boeing 737 (right), which are typical for wide-bodied rsp. <S> narrow-bodied designs. <S> Note the relatively bigger freight compartment of the Airbus fuselage. <S> Even bigger fuselages than those of the Boeing 777 or <S> the MD-11 offer so much internal volume that two passenger decks are needed to avoid flying lots of empty space around. <S> McDonnell-Douglas planned for a while to expand the passenger load of the MD-11 by adding a lower passenger deck forward of the wing, and Airbus did the logical thing and designed the A380 from the outset as a double-decker. <S> Other designs of a similar size came to the same conclusion. <S> Note that cargo volume on long-range variants of several aircraft is reduced because a fuselage tank had to be added aft of the wing. <S> In all cases the cargo volume was determined by what was left unfilled. <A> Cargo compartments in airliners are generally in two categories: regular cargo and bulk cargo. <S> This graphic shows the compartments in a 777. <S> The normal cargo compartments are generally filled with containers called Unit Load Devices. <S> These are standard containers that can be filled with cargo and easily loaded/unloaded from the cargo compartment. <S> Palletized cargo can also be loaded. <S> The bulk cargo compartment is for non-containerized cargo like loose luggage. <S> You can see that the majority of cargo space is reserved for non-bulk cargo.
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In the case of the A380, there is a large bulk hold as well as plenty of room for other cargo.
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Can I fly with an airband receiver in the United States? I'm flying with American Airlines on a cross-country flight soon and was thinking about bringing along my airband receiver/scanner since it'd be fun to listen to ATC. It looks like I'd be unable to use it during the flight since any type of radio isn't allowed. I don't see any TSA restrictions on them. Am I safe in assuming that I can bring it along and listen to it in the airport terminal without any trouble with security? <Q> This is probably more a travel question than an aviation one, but I did some Googling of various aviation and travel sites and the consensus seems to be this: <S> You can carry the scanner with you, but if you're unlucky and encounter the wrong TSA agent on the wrong day then you may be asked a lot of questions at security (the TSA's "Can I Bring..." tool seems to consider scanners to be generic electronic items) <S> Using the scanner while sitting in the airport is fine, but if you attract attention to yourself then you may be questioned by the police or airport security <S> You may not use a two-way radio on board the aircraft, because they're specifically required to be off at all times (this is in every airline's safety instructions that I've seen); that shouldn't apply to a radio that only receives but the cabin crew might ask you to turn it off anyway if they're not sure about it <S> Even if you did operate the scanner in the air, the reception is terrible and you'll probably hear <S> only the aircraft's crew, not ATC Note that this information is for the USA only, many other countries are very strict about possession and use of scanners or two-way radios and in the UK (for example) just listening to ATC is actually illegal . <A> There are restrictions on using radios (even if receive only) onboard an aircraft. <S> Furthermore, you are required by the FAA to comply all pilot and flight attendant instructions (and they usually say turnoff all radios). <S> There is however a possible loophole by using a crystal radio. <S> There's no rule against taking one onboard an airplane, and since there's no battery, it's impossible to turn off. <S> Do a search for "airband crystal radio" for possible receivers and designs. <A> I've been an avid shortwave listener since the 1950's, a ham radio operator since 1965, and I later retired as a USAF pilot. <S> Ever since the 60's when most everything went solid state and handheld radios (both scanners and two way) started to have VHF aviation frequency, and later, UHF frequency (military aviation freqs) capability, I have always traveled with a handheld radio while flying on either commercial airlines or military hops worldwide. <S> In several decades of doing this I have never, ever had any issues with either security (TSA, etc.), flight crews, or customs personnel, even with radios capable of transmitting on aviation frequencies. <S> But, just in case, I always carry copies of my credentials with me (both my ham and FAA), which are valid worldwide. <S> In addition, while on board I don't "advertise" my activities, placing my handheld in either my pocket or the seat magazine storage pocket and use a headset (with no microphone!). <S> Quite often, when either changing frequencies or using the LOC/ILS to monitor an approach someone seated near me will be curious and ask me a question <S> and I will answer their question in great detail and let them listen in or watch if they want to. <S> This serves to alleviate any concerns that they may have while also helping them better understand Ham Radio, shortwave listening, and other technical aspects of flying and the evolution of radios and the frequency spectrum at the same time. <S> But hey, the secret is to just act normal, be cordial, and always do whatever a flight crew member may ask of you, if requested. <S> For between $150-350 some of the more modern handheld radios made by Icom, Vertex, or Sporties Flight Shop will provide you with hours of entertainment on board and help generate new friends at the same time. <S> Enjoy!
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In the US, it's perfectly legal to bring an airband receiver or scanner through security and on to an airplane.
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How do I select an aircraft mechanic? So Uncle Bob just died and left me 3.14 million dollas. Or else I hit the lottery, or what have you. Whatever the case may be, I've decided that today is the day I buy myself an airplane. Harrison Ford has one and by God I want one too. This means that I need a mechanic. We can assume that I don't already know any mechanics (For the purposes of the question, we can assume I soaked my home in Cristal , tossed flaming $100 bills at it until it burned down, and then moved to Beverly Hills, away from all the little people), so: How do I find a mechanic or maintenance shop to keep my privately-owned aircraft airworthy? <Q> The key when selecting an aviation mechanic or shop to maintain your newly purchased plane is "time in type": You would not take a Cessna 172 to the United Airlines maintenance facility at JFK, not would you take an A380 to the local Cessna service center (even though it would be perfectly legal to do so). <S> If you're buying a new aircraft (of any type) <S> the manufacturer will be able to recommend an authorized service center for you, and you'll probably want to use an authorized service center (especially for warranty work). <S> If you're buying a used aircraft you can still contact the manufacturer and ask about authorized service centers. <S> They will usually be happy to give you a list of places near you that can work on your aircraft, and who are blessed by the factory to perform warranty service, complete mandatory service bulletins where the manufacturer is supplying parts / covering labor, etc. <S> Aside from manufacturer recommendations there are a lot of other ways to find a maintenance shop that beat simply asking Google and picking one at random. <S> For the most common single-engine piston aircraft (your typical Piper Cherokee, Cessna 172/182, etc.) <S> For more esoteric aircraft (high-performance singles, twins, vintage/classic/warbirds, etc.) <S> your best resource is often a type club (e.g. The American Bonanza Society for Beechcraft Bonanzas, or <S> ICS for the Piper Comanche) <S> - Google can help you track down a type club, and the members can help you find mechanics who have experience working on your particular airplane. <S> Type clubs are also a great source of other information (like where to find parts). <A> It's very, very easy to hire an aircraft mechanic. <S> Drive to your local airport and explore the less-travelled roads beside the fence. <S> Walk in, say hello. <S> Small exception: <S> major international hubs tend to be air carrier only. <S> General aviation will be somewhere else, but any maintenance shop will know where the others are - it's a fairly small community. <S> Also note that uncle Bob's 3.14 million won't buy much. <S> It will get you a really decent piston single or very light twin. <S> Or a high-time turbine in need of some pricy maintenance. <S> Remember that unlike a car, the sticker price on an aircraft is just the edge of the money pit. <S> You make yourself a 5-year budget and spend no more than half on the actual aircraft. <S> If you buy new you can shift it a bit as you won't need any unscheduled maintenance for a while but in the broad scheme of things aviation is not for the financially fainthearted. <A> I believe the best way to seek such a mechanic would be to ask the place you purchased your aircraft, asking the airfield you park your aircraft at or simply googling "Aircraft Mechanic in [insert location]". <S> If you need a link to local mechanics here is one. <A> FAA has maintains a list of mechanics . <S> You can download the entire list too. <S> This page has some related information about mechanics.
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you can almost certainly find a mechanic at your local general aviation airport - ask the FBO where you're storing the plane for recommendations or talk to other pilots on the ramp about who they use for maintenance. You will find a number of maintenance facilities that can service anything from a Piper Cub to the Concorde.
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How do I determine the VFR pattern altitude at an airport? How do I determine the VFR pattern altitude at an airport? Can I find it on a sectional? <Q> In April 2013, the FAA's Charting Group met to discuss this question . <S> The standard pattern used to be 800 ft AGL, and the Chart Supplement (formerly called Airport/Facility Directory or A/FD) was inconsistent in listing them. <S> Ultimately they decided: Chris Criswell, AJV-22, reported that, per ACF recommendation, all traffic pattern altitudes, standard and non-standard, will be added into NASR (the AFD) for all airports. <S> This will be a day forward implementation beginning in July 2014. <S> Some other places the TPA is recommended to be 1000 feet AGL: Advisory_Circular AC90-66A c. <S> It is recommended that airplanes observe a 1000 foot above ground level (AGL) traffic pattern altitude. <S> Large and turbine powered airplanes should enter the traffic pattern at an altitude of 1,500 feet AGL or 500 feet above the established pattern altitude. <S> A pilot may vary the size of the traffic pattern depending on the aircraft's performance characteristics. <S> The Chart Supplement (A/FD) will typically list the Traffic Pattern Altitude (TPA) if it is non-standard (not 1000 ft/1500 ft AGL) <S> Now the Chart Supplement (A/FD) will be the definitive guide! <A> No, it's not on a sectional. <S> The Traffic Pattern Altitude (TPA) can be found in your A/FD. <S> Edit : I just double-checked and it's not on all airports in the A/FD. <S> I would assume that if it's not listed it's 1000' AGL, but not sure why it's listed on some and not others. <S> When it is there it'll be on the 2nd line after fuel. <S> It'll look something like this: TPA-1072(1000) <A> In the UK, this information can be found in the AIS under <S> Aerodrome information - specific and is not printed in charts. <S> The section on "Flight Procedures" for my local field specifies <S> Circuits <S> (a) Standard overhead join. <S> Variable circuits. <S> Fixed wing circuit height 1000 ft QFE. <A> For a non-standard traffic pattern altitude, you will be provided an altitude, and if it's a standard traffic pattern altitude (1000' agl), then it will not display an altitude or it will be blank as I've seen before. <S> e.g. KMBS does not display an altitude but TPA is 1000' agl
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The FAA's Airplane Flying Handbook says The traffic pattern altitude is usually 1,000 feet above the elevation of the airport.
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How is the weight of an airplane measured? Many very large airplanes have specific information of their empty weight. For instance the weight of an empty, regular 747-400 is 393,263 lb (178,756 kg) according to Wikipedia. The Concorde is 78,700 kg. How is the weight of these airplanes measured so precisely (note that in the 747-400 example is precise to the unit's place!). Is the sum of the weights of all the parts used? Also, is Zero Fuel Weight (ZFW) the same as empty weight? <Q> Minute differences in metal sheet thickness, equipment and paint will make sure that there is a difference of many pounds between airplanes of the same type and furnishing. <S> Add to this the difference in seating, galleys and instrumentation between airplanes of the same type which are operated by different airlines, and a precise number as in your question becomes almost meaningless. <S> A better way would be to give a range in which most airplanes will fall, or to round the number like the Concorde weight of your question. <S> Weighing is quite straightforward: All tires of the landing gear are placed on scales and the weights are summed up. <S> If the attitude of the airplane does not change, the weight on the tires can even be measured consecutively, so only one scale is needed. <S> Small floatplanes can be suspended from a crane with a scale in the line holding the aircraft. <S> In Ernst Heinkel 's biography he remembers an aircraft deal with the Soviet Union in the late 1920s. <S> He had to deliver five floatplanes of a specified weight, and the Russian approval inspectors insisted on all planes having the exact same weight. <S> Of course the planes were not identically heavy, but his advantage was that the scale in his factory was indicating the weight by printing it on cards. <S> So the evening before the inspectors came, he let one aircraft be weighed five times, put the cards back into the machine and had the printing mechanism disabled. <S> The next day he closed the business successfully with his very happy Russian guests. <A> Addressing the ZFW question, zero fuel weight is not the same as empty weight. <S> Empty weight is the weight of the airplane without any people, bags, cargo or fuel on board. <S> Zero fuel weight is the weight of the airplane plus people, bags and cargo, but does not include fuel. <S> The ZFW is important because there is usually a limitation of maximum ZFW. <S> For example, once you hit max ZFW you can no longer add people or cargo to the airplane, even if you would stay under max gross weight including fuel. <S> The only weight you can add to the airplane above the max ZFW is fuel. <A> You get yourself some load cells, put them under the gear axles / lift points etc. <S> and jack it off the ground. <S> The attached computer will tell you the total mass, center of gravity etc. <S> Several companies produce aircraft weighing scales . <A> Be aware that if a small change is made to an aircraft, like adding or removing equipment, the airplane is typically not reweighed but it's empty weight is recalculated by adding or subtracting the weight change. <S> Also, the empty weight c.g. is recalculated by adding or subtracting the moment change. <S> As I remember, there is also an requirement that aircraft be reweighed every so many years. <S> I want to say every 3 years, but that may be wrong. <S> Also, the empty weight does not include pilots and cabin crew. <S> The term BOW (Basic Operating Weight) is often used that does include standard weights for pilots and cabin crew. <S> Air carriers, particularly freight operators, may employ more than one BOW to allow them to easily switch between configurations. <S> For example, freighters sometimes carry fly-away-kits (FAK) of several hundred pounds. <S> The kits are strapped down, but can be quickly removed if need be. <S> The operator might choose to have two BOWs, one including the FAK and one without it. <S> There's also the matter of using "fleet weights" rather than individual airplane weights, or at least there used to be.
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The empty weight of airplanes can only be given to single-pound precision for one specific airplane.
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How do pitch attitude, airspeed and sink rate come into play in a rapid descent or a dive? So, I have a hypothetical aircraft that needs to get from FL350 to 10,000' as quickly as possible. What is the difference in sink rate between a 'standard' airliner rapid descent (idle thrust, extended spoilers, and nose slightly down) vs. having the flight crew simply point the nose down below the horizon as far as they care to? How does the airspeed build-up over time differ between a 'standard' rapid descent vs. a dive? For a rapid descent, what nose-down pitch would be typical? <Q> Airspeed control is the difference. <S> For a modern airliner, this is somewhere around Mach 0.9. <S> In a dive with "nose down as far as they care to" (I read this as 90°), airspeed is not controlled, but an outcome of the situation. <S> The airliner will go supersonic. <S> It is possible to recover it from a short dive, but will incur damage to the aircraft (e.g. the pilots will need to lower the landing gear to increase drag, but lose the gear doors in the process). <S> If the pilots would only care to put the nose down to the point where they not exceed $v_D$, we are back at a rapid descent. <S> They could lower the gear in order to increase the sink speed, and circle to increase drag further. <S> Circling needs more lift (proportional to the inverse of the cosine of the bank angle), so more lift-induced drag is produced. <S> To maximize drag, the pilots should fly at the maximum permissible load factor (which is rather low at maximum dive speed due to gust loads). <S> If we assume the L/D of the airliner to be 5 with gear and spoilers deployed, the pitch attitude would be between -11° and -12° and the sink speed would be between 50 and 60 m/s (10,000 to 12,000 ft/min). <S> The bank angle would be between 45° and 60° and the plane would be violently shaken by buffeting. <S> Going any steeper than that would only be attempted by pilots with suicidal leanings. <S> Flying like described above is scary enough already. <A> 'Dives' in an airliner should really be avoided at all costs. <S> A nose-down dive could have the following dangers, just to name a few: <S> Excessive airspeed, leading to structural integrity issues <S> The 'pull out' would have a high load factor (think high G force) which would stall the aircraft (or even break it apart) <S> To 'pull out' without stalling would take a long time to level off - it would be easy to overshoot the 10k feet mark and <S> if there's high terrain... <S> You would have a cabin-load of vomiting passengers! <S> The standard emergency descent procedure will get you to a safe altitude quickly enough, with oxygen supplemented. <S> I'm sorry I can't answer your other questions <S> but I hope I have explained why a dive would not be a viable option. <A> A nose up descent with a low airspeed is best. <S> I did one on my multi engine instrument flight test. <S> The examiner thought it was great. <S> You pull back on the power to idle. <S> Raise the nose like you are wanting to enter a stall. <S> Let the airspeed wash off. <S> As it approaches maybe 10 or 15 knots above the stall, you keep the airspeed there by lowering the nose. <S> Normally when deliberatly entering a stall, you would continue to lift the nose until a wing drops. <S> But you lower it. <S> To maintain a speed above the stall. <S> The lift has already reduced enough so that the aicraft will descend. <S> But it does it with a nose up. <S> Airliners do it on every landing, but its being done with power applied <S> and so its a gentle desvent. <S> If you wanted to drop from the sky when you are way too high on an instrument flight test, its best. <S> You will drop like a stone and have a extremely steep angle. <S> With very little ground speed. <S> If you want to get some airspeed back fast, just lower the nose and apply power. <S> It you want to arrest your descent. <S> Just slam the power levers forward <S> and you are already in a climb attitude. <S> Its not for the kind of pilot who is not confident. <S> But if the plane is part of your body, you will get it naturally.
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In a rapid descent, airspeed is controlled and the pilots will keep it below $v_D$, the maximum dive speed for which the aircraft is certified.
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How to do a Rapid Descent in a jet with inoperative spoilers? So, let us assume you are in a simulator for your favorite jet plane, and the instructor gives you a LOFT (Line-Oriented Flight Training) scenario that goes as follows: A normal takeoff and climb to cruise altitude, and perhaps thirty minutes of normal cruise flight The non-recoverable loss of speedbrake (flight spoiler) functionality due to a mechanical jam, or some other malfunction such as the loss of all SECs in a FBW Airbus. Another 30 minutes of time to deal with the first malfunction: run the checklists, plan and initiate a diversion if needed. You lose normal cabin pressure for some reason, and have to conduct a rapid descent to get back to 10,000' and complete your diversion. How do you execute the descent, considering that the rapid descent procedures for most jets rely on using the speedbrakes to achieve a high descent rate without overspeeding the aircraft? To use the 737 QRH checklist for Emergency Descent as an example: EMERGENCY DESCENT . . . . . . . . . . . . . . . . . . . . . .Announce The captain will advise the cabin crew, on the PA system, of impending rapid descent. The first officer will advise ATC and obtain the area altimeter setting. ENGINE START switches . . . . . . . . . . . . . . . . . . . . . . . . CONT THRUST levers . . . . . . . . . . . . . . . . . . . . . . . . . . . . CLOSE Reduce thrust to minimum or as needed for anti-ice. SPEED BRAKE . . . . . . . . . . . . . . . . . . . . . . . . . FLIGHT DETENT DESCENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Initiate Target speed . . . . . . . . . . . . . . . . . . . . . . . . . . . Mmo/Vmo If structural integrity is in doubt, limit speed as much as possible and avoid high maneuvering loads. Level-off altitude . . . . . . . . . . . . . . . . . . . Lowest safe altitude or 10,000 feet, whichever is higher <Q> The answer is actually quite simple. <S> FOLLOW THE MANUFACTURES PROCEDURES. <S> In some aircraft (I don't have a 737 flight manual handy) <S> there is an altitude limitation if the spoilers are inop for just this scenario. <S> When the aircraft was certified, they needed to demonstrate an emergency descent (in the allowable time) without them, and that might not be possible from the certified ceiling. <S> If that's the case in the 737, then descend to the max altitude with spoilers inop (assuming that you started above it). <S> If there is no altitude limitation and no special spoiler-inoperative emergency descent procedure (I have never seen one of those, but there's nothing to say that a manufacturer couldn't have one) then you simply fly the regular procedure without spoilers. <S> The manufacturer had to demonstrate this during certification and it must have been acceptable at the time. <S> As rbp says, most of the time you fly <S> Mmo/Vmo at idle power after you don the oxygen mask. <S> IF the flight manual/checklist says that you can put the gear down (some do) then you may, but I wouldn't otherwise. <S> I certainly wouldn't slow to gear speed (unless the manufacturer says to.... <S> Unlikely in a jet like this) because you are decreasing the drag by slowing, and taking time at altitude to do so. <A> Go to the top right corner of the envelope and stay there (point D in the sample below. <S> Sorry, I don't have the 737 envelope at hand). <S> Engines idle, speed and load factor as high as allowed. <S> If airframe integrity is not critical, lower the gear to increase drag, but expect to lose the gear doors. <A> Whenever trying to rapidly descend, you always want to think drag! <S> Throttle to idle, lots of s-turns, (aileron drag), get down to gear speed, drop the gear, and lower flaps if practical. <S> A limited crabbing-like manuever (intentional side-slipping) would greatly slow the aircraft as well! <S> I'm sure that Terry will be here to recant us with a tale soon! <A> In a jet, this is based on the "barber pole" on the airspeed indicator (which changes based on altitude). <S> If the speedbrakes fail, you won't get the maximum descent rate, but you won't break the airplane by flying outside the aerodynamic envelope, either. <S> Here's a jet-type airspeed indicator with a red and white barber pole: http://www.md80.it/cockpit/cockpit/captain/kuvat/asi.jpg <S> (I have a high-altitude endorsements as per 61.31(g))
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There primary consideration in an emergency descent is to descend at the maximum allowable airspeed in the given configuration.
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Why are flaps retracted when an aircraft is parked on ground? I found this question . One of the answer tell the flaps are generally retracted after landing. I assume this mean flaps are retracted when the airplane is on the ground between flights. Flaps are extended for landing and then extended again for take off. Not taking care of their position while on ground (no need of them) and putting them in the required position before take off may save (few) flaps actions (something like putting them from landing to take-off position instead of landing position to fully retracted and then from retracted to take-off position). Is there some good reason to retract the flaps on ground? Does this good reason varies from a type of aircraft to another? <Q> A few different reasons: Good pilots put the aircraft into a well-known (up) configuration after landing, so that the aircraft is ready for use on the next flight. <S> Flaps down during taxi was a signal to the tower that the aircraft had been hijacked. <S> Take-off flaps (10 degrees on my airplane) and landing flaps (45 degrees), are nearly always different, so leaving the flaps down after landing at, say, 45, doesn't save any steps for departure. <S> If the pilots forgets to set flaps before takeoff, some aircraft (like mine) will make it almost impossible to depart and climb out on full flaps because of the induced drag, while takeoff with no flaps is possible . <S> Prevent trucks and people from hitting the flaps while the airplane is parked, especially in the full-down (landing) configuration. <S> Some pilots employ the practice of retracting the flaps during the rollout because it puts more weight on the wheels, reducing stopping distance. <S> Flaps down increases the amount of lift generated by the wing, so some aircraft might actually lift off the ground while parked with full flaps in high winds. <A> You never know what wind speed will hit the aircraft until the crew returns. <S> Also, retracted flaps are much less of an obstacle to careless drivers of airport trucks. <S> This video shows a parked 747 in high winds. <S> Now imagine what would have happened if the flaps had been deployed! <S> Note that fully extended high lift systems at ground angle of attack can produce five or six times the lift of the wing with flaps retracted. <S> Lowering the trailing edge flaps increases wing area and lowers the zero-lift angle of attack, so at ground attitude the wing is much farther up on the lift curve slope. <S> In aircraft with manual controls it is also recommended to secure all control surfaces, so they don't float in the wind. <S> Bearings and pushrods could be damaged, and in a careless preflight check might not raise suspicions, but can go on to fail in flight. <S> Better be safe and reduce all chances of wind playing with the aircraft! <A> On larger aircraft it would be standard operating procedure to retract the flaps after landing. <S> This is to ensure the crew taking over from you are presented with an aircraft in the correct state in accordance with company SOPs. <S> Flaps could easily be damaged by ground crew loading and unloading. <S> Also it would be difficult to refuel the aircraft with the flaps/slats extended <S> (Larger Boeing types have the refuel system located at the leading edge underneath a wing). <S> There are occasions when you would leave the flaps extended, during operations in heavy snow for example - retracting contaminated surfaces may cause damage. <A> and then the obvious one... <A> On Pipers (Cherokee, Cherokee Six), the flaps had step areas on the inboard ends. <S> When retracted, they were essentially locked in position. <S> When extended to the first notch, they were spring loaded in such a way that they could be pushed down to expose the hinges and linkages for inspection from above. <S> The pre-flight routine would include setting the flaps to 1 notch to facilitate inspection during walk-around, but otherwise keep them retracted until pre-take-off. <S> So a reason for keeping retracted would be to help with boarding.
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you retract your flaps so you don't keep hitting your head on the flap when you are bent over walking around your plane :)
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What should a pilot do when flying in the vicinity of parachute jumpers? There are several airfields nearby where parachuting activities routinely take place. How far away is considered to be a safe distance from the airfield when flying past it en-route to another destination? Are there any particular frequencies to monitor besides the airfield frequency? How would I know parachuting is happening besides any NOTAMs? <Q> Qualification: I worked at a busy drop zone for 10 years. <S> Just announce yourself on the airfield frequency about 5-10 minutes out <S> and they'll tell you what's going on, including which runway is active and how high they are jumping <S> from - standard altitudes are 3000ft and 12,000ft AGL. <S> At our place it was really simple: <S> left-hand for 34, right-hand for 16. <S> We landed everyone on the east side, and if we are dropping at 3000 all day you can just pop up to 4000 and be completely out of the way. <S> If you are just passing by a 2km buffer is lots - no one is likely to be in the air that far away. <S> No reply usually means nothing in the air. <A> The FAA regulations have this to say: Federal Aviation Regulation Part 105.25 requires that ATC be notified no earlier than 24hours before or no later than one hour before the parachute operation begins in Class E and G airspace. <S> Jumps in Class A, B, C and D airspace require an authorization from ATC. <S> This means that if you expect chute activity in the area, ask ATC! <S> Controllers are required to give traffic advisories to jump aircraft before the jump,and to issue advisories to all known aircraft that will transit the Class E airspace within which the jump operations will occur. <S> When time or the number of aircraft make individual transmissions impractical, advisories to nonparticipating aircraft may be broadcast on appropriate frequencies. <S> And as always, check the NOTAMS! <A> Are there any particular frequencies to monitor besides the airfield frequency? <S> How would I know parachuting is happening besides any NOTAMs? <S> Here in Seattle, jump aircraft are usually talking with ATC (Seattle Approach). <S> The jump airplane will announce 5 minutes out and the when the jump occurs. <A> <A> I'm not a pilot. <S> I did attempt to get a parachute license, but stopped after a couple of jumps. <S> I jumped at two different drop zones. <S> (And I'm from Sweden) <S> I just thought I'd offer a view from the other side. <S> At the DZs where I jumped, the pilot always talked to ATC before takeoff, so I would assume that ATC will know of any parachute activity. <S> The parachutists will fall, so if you can stay above the plane that will drop them, you'll be fine. <S> Where I jumped, 4000 m was highest allowed altitude without oxygen, so no one jumped from higher than that. <S> The parachutists will want to land at or very close to their field. <S> During the freefall part, they don't really drift with the wind. <S> Chutes will typically be opened at about 1000 m, and from that altitude, they will drift significantly with the wind. <S> Thus, they will be dropped upwind, and will typically not move very far downwind of the field, especially not at high altitudes. <S> So, in order of simplest/safest: <S> Fly above them <S> Fly downwind of their landing spot <S> If you need to fly close to their field, the higher up you can be, the better. <S> This should perhaps be taken with a few grains of salt, but hopefully others can chime in if I've said something incredibly stupid. :)
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In Europe, it's generally a good idea to be on the Flight Information Service (FIS) frequency, where you can receive information about active drop zones and/traffic information to the airplane performing the drop, as they need to call in on the FIS frequency and announce when they start the drop. Under no circumstances make a cross-field pass as that's usually right in the middle of everyone else's landing pattern, and we don't carry radios. First of all, recurring DZ's have parachute symbols on sectional charts, so look for them!
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Can I use motor oil in a aircraft piston engine? In one episode of the 'reality' show Airplane Repo a pilot topped off an aircraft engine with motor oil; I think it was a Cessna 182 but I may be wrong. What would be the effect on the engine? Is it a practical (and safe) alternative if aviation oil isn't available? <Q> By motor oil, I assume that you mean automotive motor oil. <S> In that case, it's a bad idea for a bunch of reasons. <S> First, every airplane POH I've seen has specified that the oil must qualify to a standard - either MIL-L-6082 or MIL-L-22851 (though those have been superseded by an SAE standard). <S> Modern automotive oil doesn't meet that standard, and therefore is effectively forbidden by the POH. <S> More to the point, automotive oil is bad for aviation engines. <S> Aviation and automotive engines work on the same basic principles, but many of the details are different. <S> 1 <S> One significant difference is that aviation engines normally burn some oil as they run, while well-performing automobile engines burn little or none. <S> Some of those additives do not burn completely, but instead stick around in the form of ash, where they can foul the engine and create deposits that lead to pre-ignition. <S> That is why aviation oil is ashless dispersant: it cleans the engine by dispersing combustion byproducts into the oil (to be removed on the next oil change), while being ashless when burned. <S> Lycoming considers it serious enough to put in an all-caps "CAUTION" section in their Lubricating Oil Recommendations document: UNDER <S> NO CIRCUMSTANCES <S> SHOULD AUTOMOTIVE <S> OIL BE USED. <S> THE USE OF AUTOMOTIVE LUBRICANTS IN TEXTRON LYCOMING ENGINES <S> IS NOT RECOMMENDED BECAUSE ITS USE COULD CAUSE ENGINE FAILURE. <S> If all of that wasn't enough, use of an improper oil may void your engine warranty. <S> In short: don't use it. <S> References: <S> An editorial summary on Avweb <S> An aircraft engine overhauler's best practices <S> Lycoming's Lubricating Oil Recommendations 1) Note that I'm referring to air-cooled aviation engines that burn 100LL - made by, say, Lycoming or Continental. <S> Rotaxes and new aero-diesels are different, and more like their respective automotive counterparts; in fact, Thielert engines are actually based on automotive diesels. <A> Piston engines will, in general, accept any medium-weight motor oil without complaining. <S> While you should, also in general, use what the manufacturer specifies you can get away with quite a lot depending on the amount and your intentions. <S> One litre low, moderate climate, short trip, planning on an oil change anyway? <S> 7-11 brand 10W30 will be fine. <S> Ferrying across Alaska in winter with 2 "overnight" stops? <S> Better use the good stuff. <A> I used to read World-WarII adventure stories, one in particular rings in my mind. <S> A PBY landed at a remote location, in the South Pacific with one engine badly leaking oil. <S> At the remote base all they had had on hand was cooking oil. <S> The pilot ordered the engine to be filled with cooking oil, intending to get the plane off the ground, then shut it down. <S> But the engine was running so well, that he kept it running and running, and running, and some hours later he landed at the home base. <S> The crew removed the engine, then sent it to the manufacture, telling the story, at the factory, they took the specs of the engine, and found that the cooking oil had done no damage. <S> The engine was fine. <S> .Moral of the story, you can run cooking oil in an aircraft engine.
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Automotive oil contains a number of additives, such as detergents and wear inhibitors, intended for use where the oil doesn't burn off.
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What are the advantages and disadvantages of having landing gear doors? To make comparison easy, let us take the example of B737 and A320, both similar aircrafts with retractable landing gear. As seen on the photo below, the B737 doesn't have gear doors for the wheels, but the A320 does Obviously, Boeing and Airbus made different choices for the same feature and both seem reasonable. Both aircraft models are well accepted by the airlines. What are the advantages and disadvantages of both designs? EDIT: I put links to other images where both aircraft are retracting landing gear after take off. The difference is obvious as we can see the landing gear doors operated for the A320 and no doors for the B737 's wheel. <Q> Benefits of gear doors With gear doors, there are fewer constraints on the retracted gear position. <S> This is especially important in larger aircraft with larger and more complex landing gear. <S> It doesn't need to be flush with fuselage or streamlined (737 also uses hubcaps ). <S> Extra weight for the door and the mechanisms Extra complexity of opening another door (possibility for things to go wrong ) <A> Doors add weight and complexity to the aircraft, and need to be inspected and maintained. <S> But doors also provide a smooth surface for the air to travel over, so they would have less drag. <S> The 737 does have doors, but for the gear struts, but the wheels lay fairly flat against the fuselage, so drag is minimized. <A> Also, in Boeing's case. <S> it was decided to eliminate doors because they add COST. <S> When they were designing the 737, it was a relatively small, budget aircraft being built for regional service.
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The gear doors provide a good aerodynamic surface Opening to gear bay can be larger and easier to access Drawbacks of gear doors
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Why do passenger embark on the left side of an aircraft? I speak of passenger aircraft that can be found on large airports.The left side is used by passengers (and the crew) to embark/disembark (see the position of jet bridges ) and the other side to embark/disembark the rest (e.g. food). Why do we always use the left side for passengers? What prevents an airport from deciding to use the other side? If this is an historical decision (e.g. one day in the past an aircraft builder decided passenger should use the left side, then majors airports were built accordingly and thus new aircraft were built accordingly and thus new airports were built accordingly), is it possible and reasonnable to build a jet bridge made to operate on the right side of an aircraft and then use the right side for passengers and the left side for the rest? <Q> Why do passenger embark on the left side of an aircraft? <S> Because the cavewoman who invented the log-canoe was right-handed? <S> Note <S> : I arrived at this answer by looking at a kind of etymology of the terms starboard & port but that's incidental. <S> The answer to this question happened to be contained in an answer to a rather different question. <S> Some groups of aviators may have dropped the archaic terms while still being subject to a continuation of an archaic habit/convention. <S> People get on the left side of a jet airplane because Vikings (etc) steered their wooden boats with a steering board (hence starboard?) <S> held in their dominant right-hand. <S> Since it was inconvenient to have your steering apparatus wedged against a quayside (or earthen bank) <S> they docked at the port along their left side and therefore loaded and unloaded on the left. <S> Farhan's comment leads you to this answer in English.se which I reproduce here for convenience Excerpt from trivia on the Navy website <S> : Port and starboard Port and starboard are shipboard terms for left and right, respectively. <S> Confusing those two could cause a ship wreck. <S> In Old England, the starboard was the steering paddle or rudder, and ships were always steered from the right side on the back of the vessel. <S> Larboard referred to the left side, the side on which the ship was loaded. <S> So how did larboard become port? <S> Shouted over the noise of the wind and the waves, larboard and starboard <S> sounded too much alike. <S> The word port means the opening in the "left" side of the ship from which cargo was unloaded. <S> Sailors eventually started using the term to refer to that side of the ship. <S> Use of the term "port" was officially adopted by the U.S. Navy by General Order, 18 February 1846. <S> So it's a historical convention, many arbitrary choices are of this sort. <S> Pioneers of a new form of transport adopt the terms (port, startboard) and habits of more ancient forms of transport. <S> Ironically, since aircraft became able to carry substantial non-human cargo, the cargo entry has moved to the other side to reduce the chances of crushing the human cargo with the non-human cargo. <S> Presumably also because having lots of large holes all in one side may be structurally disadvantageous. <A> Early fighters with a cockpit (Supermarine Spitfire, Messerschmitt 109) had cockpits which were hinged on one side. <S> For a right handed pilot (the majority), it was easier to lift the canopy over your head and to the right, hence the hinge was on the right. <S> This made the left the obvious choice for disembarking, and since airfields slowly became set up for exiting to the left and fuel to the right, newer designs maintained the door on the left. <S> If your stands are set up for one direction, you may as well order your new plane to fit the same workflow, so even when hoods were modified to slide backward, there was no need to change the door side (most designs were incremental, so the door was already there... <S> Why move what already works?) <S> This continued as air bridges and similar were introduced, and it would now be pointless to make an aircraft with doors on the other side, as you'd just be increasing your loading/turnaround times. <A> I expect it comes from the fact that aircraft development started in countries that drive on the right side of the road. <S> The pilot sat on the left because, well, that's where drivers sit. <S> The early airliners would park with the "terminal" / shed / tent / hole in the fence on the left side so the pilot could steer without hitting anything (better view out the window), the pilot could climb out his door and open the rear door to unload the mail without walking around to the other side of the plane so that's where the cargo handlers / trucks / horses would wait. <S> Remove the front door on larger aircraft, replace it with a rear door closer to the ground. <S> You still put it on the left for compatibility with all the other stuff flying. <S> Fast forward to the modern day <S> and we find that we have to pick one side or the other, everything has a left door, some have doors on both sides, so.... <S> I've considered that monsters like the A380 should use jetways on both sides but making a jetway reversible <S> is mechanically very complex. <S> Economics kick in here as the largest planes are not used for short routes where a 30-minute turnaround matters. <A> The earliest air forces in Europe derived from cavalry regiments, flying was expensive and the preserve of the rich - as was the cavalry. <S> Because a right handed horseman carries his sword on the left, he will mount a horse from it's left side - so he throws his right leg over the mount. <S> This is why the pilot in command sits in the left seat and enters from the left side of the aeroplane. <S> When passengers started entering through a door the same tradition continued.
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The cost of dual-side jetways doesn't have a reasonable payoff. It's also easier to climb up an aircraft if your stronger arm is toward the fuselage and handholds.
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Does it make sense towing airplanes to the head of airstrip by external (eg electric) means? Does it make sense towing airplanes to the head of airstrip by electric means, whether internal or external? Taxiing from the gate to the runway on jet power seems like a waste of fuel. Is it possible and it would make sense to tow the airplane to the start of take-off run by a motorized towing unit or perhaps with electric motors in the airplane's landing gear? Was this ever tested or assessed? <Q> Was [towing unit or motors in landing gear] ever tested or assessed? <S> Yes. <S> 2014 <S> Main Gear <S> Using the Auxiliary Power Unit (APU) generator to power motors on the main wheels, the EGTS taxiing system allows aircraft to push back without a tug and then taxi without requiring the use of the main aircraft engines. <S> One wheel on each main gear is equipped with an electric motor to drive the aircraft From EGTS <S> Airbus signs MoU with Honeywell and Safran to develop electric taxiing solution for the A320 Family From Airbus press release <S> Lufthansa Technik has proven with a technology demonstrator that aircraft can be driven on ground by electric motors. <S> From Lufthansa Technik (with video) <S> 2015 <S> Towing Unit <S> From Wikipedia 2016 <S> Nose Gear <S> Honeywell and Safran have pulled the plug on their jointly conceived electric taxiing system, while rival developer WheelTug aims to enter service with its system in 2018. <S> "After thorough market analysis", the US supplier says, the two partners "agreed to stop work on the Electric Green Taxiing System due to dramatically lower oil prices and the current aviation industry's economic environment". <S> EGTS had been scheduled to enter service this year, with Honeywell and Safran having planned to produce a system for line- and retrofit on A320-family and Boeing 737 jets. <S> Meanwhile, Gibraltar-headquartered WheelTug plans to enter service with its nose gear-mounted electric drive system in 2018.... <S> initially on 737s and, at a later stage, on A320-family ... <S> Neither Airbus nor Boeing are supporting the programme From FlightGlobal <A> Variations on this kind of scheme and designs are currently being worked on. <S> Tugs of various sorts have been used at various places as well. <S> Also consider that various engines need time to warm up before applying full throttle, sometimes just a few seconds, others a few minutes. <A> This is an older question, and I have no answer <S> , just experience: <S> When I flew from Frankfurt (FRA) to Geneve (GVA) in January 2015, we were towed by a tug nearly all the taxiway to the runway. <S> We turned to the parallel taxiway "N north" to get rid of the tug, then went back on taxiway "N" to the runway. <S> Here is our way as tracked by my mobile GPS: <S> The pilot told us in advance that we will to this, and that it is some kind of experiment / project / study about if it works. <S> (I guess more from logistics / operation side) From my data, I also have some time information: 12:12: <S> End of push-back 12:15: Leaving terminal 12:21: turn right on "N North" 12:22: <S> get rid of tug, start engines12:27: <S> Start moving again, and back to "N" 12:29: arriving at runway 12:31: accelerating If I remember correctly, the engines were started when we were on "N north", so 5-6 minutes before takeoff. <S> However, we were taxiing to that place 20 without engines. <S> It would be interesting to know how much fuel could be saved by this procedure <S> (It was a A320 or similar, I don't know), but at least, the aircraft didn't need any extra equipment. <S> (And yes, it was an ordinary tug, not this electrical stuff or similar.) <A> Along with fitting electric motors to allow push-back without a tug and more efficient taxiing, there is a plan to use tugs controlled by the aircraft for the taxi. <A> One simpler alternative for multi-engine aircraft is to taxi out with only some (or just one) of the engines running, starting the remainder within a few minutes of take-off. <S> It might not save as much fuel as, say, a tug, but it can be done with existing aircraft and without any extra equipment. <S> The major drawback of any of these approaches is that running time during taxi contributes to check-out of the fuel, fuel system and other engine systems which all have to perform properly for a safe take off. <S> Delaying engine startup reduces/limits the opportunity for such checks. <S> Nevertheless, I think this practice has been done/is being done in some situations.
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As of 2015 Taxibot, a semi-robotic towbarless tractor which meets and connects to aircraft, is the only alternative taxiing system certified and currently in use by airlines in the market. From what I remember, using electric motors are still pretty expensive, and also you're using them for a very short time frame, such that you're lugging around extra weight that is useful for a tiny portion of time(aka more fuel burn).
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Why is AVGAS so much more expensive than car gas? Why is 100LL so much more expensive than gasoline for cars? I get the fact that it's 100LL, instead of 87, 91, etc. For example (as of now, 13 Oct 14), the 91 unleaded gas at my local gas station is 3.41USD, and the 100LL at my local airport is 5.49USD (for the self serve). What's the reason for the huge increase in price between car and aviation gas? <Q> Despite the "low" moniker there actually is a lot of it in there, and it's toxic. <S> This fuel is expensive for a number of reasons: <S> The lead itself is expensive The lead additive means that a refinery must shut down and clean the lead before producing other fuels, this means more refinery time and therefore more costs <S> Lead in fuel cannot be allowed to contaminate other fuels so you cannot pipeline leaded fuel. <S> It has to be transported in containers, adding to shipping costs <S> There are extra controls around the lead in many parts of the world, namely storage requirements and paperwork, all which costs 100LL fuel has many more "aromatic" hydrocarbons than mogas (auto fuel) in order to increase the octane levels and prevent fuel from vaporizing in your lines at high altitude. <S> It's much higher grade, so it costs more <S> It would cost even more if it were taxed the same! <S> Efforts are underway to come up with a 100LL replacement that will work the same in all engines and situations, which is a hard problem to solve. <S> Whatever fuel they come up with, while having no lead, will still likely be more expensive than mogas just because of the more expensive hydrocarbon mix and the specialist nature of the fuel. <A> The distillation and refining process for 100LL is more expensive than the process for 91 unleaded. <S> 100LL has a high octane index, and is treated to be less volatile (in particular at high altitudes). <S> 100LL is also perfectly dry in order to prevent icing. <S> Also, 100LL is produced in smaller quantities than car fuel, so economies of scale are also a factor. <S> In fact, due to the high price of aviation fuel, certain low-powered engines can be certified to fly with the same gas you put in your car. <A> What's the reason for the huge increase in price between car and aviation gas? <S> There are many differences, as other answers mentioned, but not as big as the experienced prices show. <S> But by only focusing on the product it's easy to miss cost involved in distribution and sales. <S> An FBO has at least the same, usually much higher, fixed cost than an average gas station which need to be spread over a much lower number of customers. <S> The fact that a C172 needs more gas (like 50 vs. 15 gallons) isn't much of a relief either. <S> In addition I don't know of many gas stations providing a lounge, free coffee (and sometimes sandwiches), internet access, flight planing tools and so on, all the way to courtesy cars. <S> All of this leads to a higher price per gallon than what's caused by the raw gas alone. <S> The effect can be easily seen where auto gas is offered for ultralights, or diesel for capable engines. <S> They carry a visible mark up compared to the gas station next door. <S> Then of course there's the same effect that lack of competition has on auto gas. <S> Fields with a single FBO are often priced much like the sole gas station on a lengthy stretch of highway ... <S> slightly above average.
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The LL of 100LL stands for Low Lead as it has tetra-ethyl lead added as a detonation inhibitor for high-performance engines. It's a specialist fuel made in much less quantities than other fuels, so a premium is added to ensure a profit Keep in mind that the Avgas is taxed less than Mogas in most places.
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Why does the F-111 sometimes squirt a giant fire plume behind it? (NOT afterburners!) As seen in multiple pictures: First, this one, it appears the aircraft is spraying copious amounts of fuel into the exhaust! Surely this provides no thrust, not in the way an afterburner (which the F-111 has!) does. Is it perhaps as an alternative to flares for anti IR missiles? It seems logical, but I don't think so, because I've seen it on takeoff too! At any rate, it is QUITE badass! EDIT: YouTube video! EDIT: Can any other aircraft perform this? <Q> The F-111 has, like many aircraft, a fuel dump port so it can get rid of a lot of heavy fuel rather quickly. <S> Most aircraft have the dump ports on the wings, the F-111 designers put it in the tail between the engines. <S> End result is if you dump fuel and briefly light the afterburner you will ignite the liquid fuel in your wake creating a rather spectacular trail of fire. <S> Aerodynamically it's completely useless, financially it's very expensive, you'd only do it in combat if you were suicidal as it greatly increases your IR signature right where you don't want it, but at an airshow it does look totally badass, especially as the afterburner is adding a lot of noise at the same time. <S> I would expect any pilot who does a dump-and-burn outside of an airshow (or an emergency) will have his own tail set on fire by the air wing's commanding officer. <S> The SR-71 had a similar issue - it leaked like a sieve on the ground. <S> Rotating for takeoff would occasionally set fire to the JP-7 on the runway leaving a burning trail behind it much like the Road Runner. <S> Reply to the video <S> : watch the takeoff section carefully. <S> You can clearly see the afterburners come on before the fuel dump starts. <S> Reply to about half the comments: Highly unlikely they designed it to do this. <S> The F-111 was one of the earlier swing-wing planes, that meant that you can't put much on the wings. <S> And as the bigger tank is in the fuselage anyway, someone would have looked at the space between the engines and thought it was just right for a dump pipe. <S> The flame effect was probably discovered later. <A> There was at least one occasion when the dump-and-burn was used in combat. <S> During the 1986 attack on Libya <S> the U.S. pilots, desperate for fuel, jostling with one another in the air to get access to aerial refueling tankers. <S> Unable to break radio silence, they could not locate the giant KC-10A Extenders and KC-135R Stratotankers that would keep them from crashing into the sea. <S> An F-111 pilot finally solved the problem by doing a "little torching," as he dumped some fuel and ignited it with his afterburner, "creating a huge explosion that both lit up the sky and pointed the direction to the tanker" <A> I used to be an F111 test engineer; the jet can hold about 19000 liters of fuel (without external tanks). <S> At 0.81kg/Liter, that's 15390Kg (33,939 Lbs) of weight, which is substantial (the empty weight of the jet is <S> 45200 Lbs / 20,500 Kg ). <S> Basically with a full load of fuel, the jet is 75% heavier. <S> The fire is because the pilot lit the afterburners whilst dumping fuel. <S> Assume you loose your flaps, or maybe you discover the brake lines are leaking... <S> if you had to land on a short field (such as a small civilian airport), it makes sense to dump your fuel <S> so you have a better chance of stopping quickly. <A> We did have one "practical" application in "torching" as we used to call it: <S> It was great way to find a Lead aircraft in a night formation to complete a night rejoin. <S> Also we often considered it as a useful combat technique that if we got attacked by another fighter we would plan to start a dive towards the ground and we would do a short torch just before leveling off since the flash would clearly distract the attacker and make them think we hit the ground and break off the attack. <A> The "Dump and Burn" as it was called here in Australia was used for 'effect' at air shows and for 'promoting' the Air Force as a great place to be. <S> The 'effect' was really quite spectacular. <S> And frightening to those who saw it for the first time, like here in Brisbane, resulting in many phone calls to the police of a OFO sighting. <S> As used by some American pilots in SVN on missions to light up the area they were flying through too, for a better idea of just how close to the ground they were.
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Although the giant flame plume is cosmetic, the F111 can dump fuel like this in case you need to quickly reduce the weight of the aircraft; in-flight emergencies are one possible reason to reduce weight quickly.
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Is triskaedekiphobia (fear of the number 13) the reason commercial planes normally do not have a row 13? When I first time heard this "legend" I couldn't believe it. I was really surprised, if not shocked, to actually find row 13 missing on my next passenger flight. (I believe it was a Boeing 737.) Is this really due to superstition about the 13th row? Was it so hard to push aircraft producers to renumber all other seat rows? I know that people can be absurd about their superstitions. But realistically, the odds that a passenger airplane will crash are minimal. And should it really crash, chances that you'll survive due to being seated in row 12 or 14, as opposed to 13, must be below statistical error. I find it very difficult to believe that people would choose not to fly simply due to superstition about being seated in row 13. Is there a more rational explanation? EDIT (after Patrick's answer): I don't know, if I expressed myself enough clearly. I don't think, that people are dumb, because the're worried about number 13 . I rather think, that thinking, that row 13 is unlucky , specifically on airplanes (where, in case case of crash all seats mostly are equally unlucky) is a bit weird. <Q> Fear of number 13 is known as Triskaidekaphobia . <S> I randomly entered some flight numbers on SeatGuru and found that this one has row 13 (aircraft is B737): <S> In this case, there is no 13th row: <S> However, in this case, several row numbers (12, 13, 14) are skipped to adjust galleys and lavatories. <S> This could be that they were added later or can be removed in future to add more rows. <S> If a plane is about to crash (God forbid) <S> I would be worried about being on the plane, rather than just the seat number. <S> There are several studies that safest seats are in the back. <S> So, rows 1-12 may not be as unlucky as row 13. <S> If you have 12 million dollars and I can give you one million more 1 , would you not take it? <S> In several parts of the world 13 is a lucky number . <S> 1 <S> Trust me <S> , I will not do it, even if I have that much money. <A> Aircraft producers don't choose numbering schemes, it's up to the airline to specify layout, row numbers, lavatory placement, etc. <S> It costs them little to do so and it shows their good will. <S> They'll go out of their way to skip the number 13 but they skimp on decent food and legroom. <S> It says something about the industry, doesn't it? <A> It might also be economical thinking behind it: Many people in the west do not want to sit in row 13, so leaving it completely out makes it one less special wish customers can utter (and therefore one less thing the airline has to care about). <S> Source: <S> Worked beside my studies at several places. <S> One was a European airline's help-line. <S> They had no. <S> 13 and we had an incredible number of calls of people asking to be re-seated... <S> Not having a 13 solves this problem entirely. <S> By the way: I find your wording in the question very aggressive towards people with this issue. <S> It sounds like you considered them dumb. <S> In fact it is people of high intelligence who tend to be neurotics of this kind. <S> I had a professor back at the ETH who hated the number 17. <S> He's well-renowned and well-known in his area but wherever he goes, he will never sit on seat 17, in row 17 or reside in room 17 (or even just ending in 17). <A> Why would you not do this, and risk upsetting a minority of your paying customers who may have a less enjoyable flight because they are superstitious? <S> It isn't particularly relevant whether you think it's silly <S> : it's a cost-benefit thing. <A> Consider that in Italy number 17 is also an unlucky number. <S> This is why Alitalia (amongst others) removes both rows 13 and 17 . <A> I don't know about airplanes, but I believe it is the reason why hospitals do not have any room labeled as room 13 on any of their floors. <S> Room 413 on the 4th floor is labeled as room 414. <S> I can only assume that patients who are already anxious about their illness will reach out for an excuse, no mater how absurd, that might be hindering their recovery, and therefore they result in having Triskaidekaphobia. <S> It is their attempt to find something to blame. <S> Hospital administrators do not want to be constantly handling complaints and requests from people asking to be moved to another room, so they simply have no room 13 to begin with.
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Airlines think about their customer base, and in the western world the occasional person has a fear of the number 13 so some airlines choose to skip the number 13. The bottom line is that regardless of what you name it, there remains a 13th row. It's essentially 100% free for an aircraft production team to skip row 13 and go straight from 12 to 14, when numbering.
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How does a large airport switch flow? Airplanes prefer to land into the wind, and airports adjust for changing wind direction by changing the active runway. I've been flying a small plane in the pattern when the tower asked me to do a 180° turn to reverse the pattern. But at a large airport with traffic continuously coming-n-going, with fast moving jets that fly enormous patterns, how do they switch directions? It seems logistically complicated. <Q> It's not too logistically complicated on its own. <S> You just stop takeoffs, start taxiing the conga line of waiting airplanes to the new runway, let airplanes currently on final land, and start vectoring the other airborne flights toward the new approaches once the last of takeoff traffic is away. <S> Once the new landing flow is established, start releasing the takeoffs. <S> This will require coordination between tower and approach and may involve the center if flights need to be put in holding during the transition (depends on how busy the airspace is). <S> In certain busy airspace this may also require coordination with other nearby airports. <S> With that said, some airports that take off and land on different runways can have impacts on arrival rates in different configurations, and this adds to the logistic complication. <S> One example is KIAH, which in normal flow is taking off on the 15's and landing on the 26's and 27. <S> It isn't too much trouble to switch landing traffic to the 8's and 9, but if takeoffs have to be switched to 33 then the flow rates are negatively impacted. <S> It gets even worse if landing and takeoff traffic have to be put on the same runways. <S> How the arrival and departure flows are impacted (if at all) from a runway switch will depend strongly on the specific geometry of the runways. <S> Anecdotally, the logistic impact of reduced arrival and departure flow is probably the largest impact. <S> At KIAH they will run their normal flow until the wind gets so bad that pilots start refusing clearances for tailwind limitations, and only then will they switch the departures to northbound. <S> Similarly, as soon as the tailwind is legal, they'll switch back to southbound departures. <A> The key is holding patterns . <S> At any of these points, ATC can instruct a plane to "hold", which means they fly a racetrack pattern passing over that point again and again until released. <S> This essentially stops the inbound traffic from coming any closer. <S> Note that multiple planes can be "stacked" over the same point at different altitudes, so <S> just a few points can hold dozens of planes if needed. <S> (For low-traffic airports, which often don't have arrival procedures, holds may not be needed at all; ATC can just give inbound planes a few extra vectors to kill time.) <S> If the destination airport needs to change runways, any plane already past the last holding point will (usually) be allowed to continue, but all new arrivals will be put in a hold. <S> Once the last plane is down on the old runway(s), ATC starts releasing planes from the holds to continue on to the new runway(s). <S> For a while, new arrivals will still get put in a hold while earlier ones are being released, but eventually the stacks empty out and planes are once again flying the entire arrival procedure without any holds along the way. <S> These same holding patterns are also used when bad weather limits the arrival rate of the airport due to increased separation requirements. <S> If that lasts long enough for the holding stacks to start getting full, other ATC units will start holding planes at points further and further away--possibly on the ground at their origin if needed--or even diverting them to other airports. <A> The idea of an orderly airport directional reversal is appealing, and it probably happens if the wind direction changes slowly enough. <S> However, once I was a passenger flying out of Chicago O'Hare (ORD) and was fifth or sixth in line to takeoff after maybe ten minutes of "waiting" (slowly taxiing) in a long line of aircraft. <S> Suddenly the plane is braked to a full stop and the pilot announced—quite annoyed sounding—that the airport is being turned around and we will be taxiing around the airport for awhile, sorry for the inconvenience <S> , we'll get you on your way soon, yadda, yadda, yadda. <S> I wish I'd had an airport diagram to see what the situation was, but we taxied for a full 55 minutes and crossed several runways. <S> My sense of direction suggested that we had gone nearly full circle around the tower. <S> (In case it makes any difference, this was in a cold February.)
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Busy airports have charted "arrival procedures" which tell inbound IFR planes to follow a series of named points called "fixes" or "waypoints".
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Why would a Su-25, which has more power and is much lighter than an A-10, only fly half as high? On the web, on several sites, the A-10 is listed with a ceiling of 14 km, the Su-25 with 7 km, although there is data that puts the height for the Su-25 at 10 km. Nevertheless, why would the Su-25 fly only half as high as the A-10 knowing that the Su-25 has more engine power and is much lighter? <Q> Just look at the wing loading: The Su-25 has between 585 kg/m² (regular Su-25) <S> and 691 kg/m² (Su-25TK) when fully loaded, whereas the A-10 has a wing loading of 316 kg/m². <S> This alone should explain why the Su-25 cannot climb as high. <S> Even when flying at minimum mass, the Su-25 has still 309 kg/m² <S> (345 kg/m² for the Su-25TK), and the A-10 is almost a glider by comparison, having just 208 kg/m² at minimum mass. <S> Since both are subsonic designs, they have a strict limit on maximum speed. <S> With that, wing loading and the airfoil determine their ceiling if thrust is sufficient. <S> Another limiting factor is the cockpit: Since the Su-25 was designed for ground attack, it has an unpressurized cockpit. <S> This detail limits the certified envelope, even though a lightly loaded Su-25 can climb higher than 7000 m. <A> I may be mistaken, but you seem to be using the same logic one would use to assess automobile performance. <S> With a car, power to weight affects one of its major performance characteristics: acceleration. <S> With a plane, power to weight still affects acceleration performance and (ultimately) top speed. <S> But it has less to do with how high the plane can fly. <S> Altitude is determined by the design of your wing and at what altitudes the engines can function. <S> Remember, as you go higher there is less air. <S> Less air means that the wing produces less lift, and it also means that the engines will often produce less power. <S> You can compensate for this by other design means (like adding a turbo to the engine for example), but if you don't eventually you'll get to an altitude that you can't get past. <S> To be fair, both of these aircraft are designed for low altitude flying (ground attacks, mostly). <S> So it would be mostly pointless to fit a bunch of stuff to allow the craft to fly much higher than a couple miles or so. <S> Thus I'm willing to bet the engineers just skipped out on that stuff to save weight for other things (like guns, missiles, armor, etc). <S> This, of course, all assumes that the information being given out on the craft is accurate. <S> I'm sure it's all top secret, and I doubt Russia or the US are going to just hand out hard numbers. <S> jwenting commented that, in reality, the difference between high altitude and low altitude design generally has to do with optimization, not adding "stuff". <S> This is a great point, for some reason my head was thinking "turbo/supercharger" (which doesn't even make sense with jets). <S> I would maintain that, in many cases, you are adding stuff to get to a higher altitude (pressurization stuff, for example). <S> But, and this is jwentwings main point I think, <S> when you look at the aerodynamics of an aircraft the main difference is a matter of optimization. <S> A wing that has good lift, good maneuverability and good stability at low altitude/speed, is not going to be so great at high altitude/speed. <A> Engines have different performance at different altitudes first of all. <S> Additionally, I would suspect (I can't remember) that the SU-25 doesn't have pressurization equipment. <S> Additionally, the wings on the SU-25 are smaller.
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An aircraft generating less lift can't fly as high, and this is likely the main reason.
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How is engine thrust measured in flight? When aircraft engines are evaluated in a test flight, how is the thrust of the engine measured? You would need accurate thrust numbers to calculate the real-world specific fuel consumption (i.e. not in a controlled environment like an engine on a test bed). I'd assume it is nearly impossible to measure thrust indirectly with any accuracy since so many factors are involved (wing shape, wind, air density, lift, ...). So I guess there should be a way to measure thrust directly , probably in the engine pylon. So how is engine thrust measured in flight? <Q> VectorVictor gives the right answer for jets. <S> However, for propeller aircraft this is really hard, and in the end only the difference between drag and thrust can be measured. <S> You are right, in the end it is impossible to produce a precise measurement of thrust. <S> The most important part of the measurement is actually a precise definition of what thrust <S> is: <S> How do you account for the increased friction drag in the propeller slipstream? <S> Is cooling drag part of the airframe drag, or should it reduce thrust? <S> Measuring thrust is foremost an exercise in precise, meticulous bookkeeping. <A> Engine thrust is measured in flight by EPR - Engine Pressure Ratio. <S> EPR is the ratio of the turbine exhaust pressure divided by the pressure measured at the fan or inlet. <S> Indeed this is the measure used for a number of engines for setting thrust. <S> More detailed airborne testing of engines is done during development, most manufacturers have airborne testbeds. <S> The parameters recorded here probably measure in the hundreds or even thousands... <A> For simple platforms, load-cells can be attached in between the propulsion system and the airframe. <S> This allows the propulsion force to be measured. <S> This force data excludes aerodynamic integration effects, such as: propeller stream effects for nose-propped aircraft, and fuselage blockage for rear-propped aircraft engine cooling drag (which is an aerodynamic property of the particular engine/propulsion integration) <S> accelerated air over the airframe (in-body jet engines, or propeller aircraft) <S> This is not an absolute requirement to assess the performance of an engine. <S> Especially, if the aircraft can fly with another engine or if the drag characteristics of the aircraft is known by some valid method, instead of a direct measurement, indirect calculations can be done. <S> For example, for constant speed and level flight, thrust = drag for accelerated level flight F_net= <S> Mass * acceleration, etc. <A> A new or overhauled engine's thrust on a manufacturer's test bed is measured against a load cell or thrust meter at given RPM, TGT (Turbine Gas Temperature),fuel flow and EPR (Engine Pressure Ratio). <S> When the certified engine is installed in the airframe and ground run, after taking into account local atmospheric conditions,intake and jet pipe losses, the maximum EPR, or thrust, and TGT and fuel flows can be cross checked. <S> In a test flight, given the correction factors for altitude and speed etc, against the known parameters of EPR, TGT, RPM and fuel flow, the engine can be seen to be giving required performance. <S> If the the engine parameters are correct but aircraft performance (i.e. speed and rate of climb) are low then suspect the airplane's weight and/or drag (flap, doors, panels etc poor fit) as possible culprits. <S> Its not fair to expect an engine to push a dirty heavy airplane up that big hill on a hot day is it?
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By measuring the brake power of the static engine and the drag of the aircraft in a windtunnel, some data points can be acquired which help in calculating what the real thrust in flight could have been.
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Are there any twin engine aircraft without counter-rotating props? All the twins I have checked have counter-rotating blades, so I was wondering if this was true for all twins of if there are any twins that have both blades turning in the same direction. <Q> Twin enigned aircrafts without counter-rotating propellers <S> A great many twins don't have counter-rotating props: <S> One such aircraft is the BeechCraft Baron 58, as seen in this YouTube video . <S> Another aircraft I can think of is the King Air 350. <S> It is not any more or less common to have one or the other. <S> Contra-rotating propellers <S> Another interesting solution to the P-factor (prop pulling towards one direction), especially on single engine aircraft is contra-rotating props , two propellers on the same shaft that spin in opposite directions. <S> This is mainly for single engine racer aircraft, but there are multi-engine aircraft known to have it, such as the Soviet Tu-95 Bear bomber. <S> The pic shown here is a Spitfire Mk. <S> XIV: <S> A better explanation of the P-factor P-factor is the term for asymmetric propeller loading, that causes the airplane to yaw to the left when at high angles of attack. <S> Assuming a clockwise rotating propeller it is caused by the descending right side of the propeller (as seen from the rear) having a higher angle of attack relative to the oncoming air, and thus generating a higher air flow and thrust than the ascending blade on the left side, which at the other hand will generate less airflow and thrust. <S> This will move the propellers aerodynamic centre to the right of the planes centreline, thus inducing an increasing yaw moment to the left with increasing angle of attack or increasing power. <S> With increasing airspeed and decreasing angle of attack <S> less right rudder will be required to maintain coordinated flight. <A> Another interesting issue that effects aircraft with non counter rotating props is that they would have a Critical Engine . <S> This in basic terms means that it's worse if a particular engine fails. <S> The Diamond DA42 which is a popular modem trainer has this issue if the left engine fails. <S> The following from Wikipedia explains further. <S> Critical Engine <S> The critical engine of a multi-engine, fixed-wing aircraft is the one whose failure would result in the most adverse effects on the aircraft's handling and performance. <S> On propeller aircraft, there is a difference in the remaining yawing moments after failure of the left or the right (outboard) engine when all propellers rotate in the same direction due to the P-factor. <S> On turbojet/ turbofan aircraft, there usually is no difference between the yawing moments after failure of a left or right (outboard) engine. <S> An engine can also be called critical when it is the only engine that drives a hydraulic pump for augmenting/ boosting flight controls. <A> Piper Twin Comanche was available in both configuration, but the most popular one had the engines turning in the same direction. <S> Aztec and Apache are also models with engines spinning the same way. <S> It makes sense that way as they share engines with singles, so one particular spinning direction is going to be much more common and spare parts will be easier to get...
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My experience is that most light twins have the same direction and that counter rotating is the exception.
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Is it possible to takeoff without flaps extended? related questions: landing wihtout flaps takeoff with full flaps My question focus on passengers jets (goes from Embraer E-jet family to Airbus A380). I don't know why pilots would attempt to takeoff without flaps but lets say they will. Considering all the other parameters are good enough (no crosswind, long runway, aircraft light enough,...) and the pilots are aware of this unusual takeoff configuration and adapt their action accordingly (including increasing $V_r$ and $V_2$), is it possible for any passenger jet to takeoff and stay airborn (not like the flight spanair 5022 ) without extending flaps? <Q> Yes take-off without flaps is possible. <S> It results in a better climb gradient, especially with one engine out. <S> The one engine out climb gradient is an important and sometimes limiting factor in take-off calculations. <S> One important constraint is the length of the runway. <S> Another limitation, perhaps less obvious, is the maximum rolling speed of the wheels. <S> The tires are rated to a limited speed which may be exceeded by a flap-less take-off. <A> Thanks to DeltaLima for the Answer, I want to add the Fokker 100 to the Planes with no-flaps take-off capabilities. <S> But as said you need a higher take-off speed. <S> also stated in table: <A> you can make a brick take off without flaps, if you put enough power behind it, and those jets have enough power, (as long as the runway is long enough for those particular hunks of metal) <S> a good question can be added on, how long of a runway does a 'xxx' need with half load, with empty load, with full load and fuel, with broken flaps. <A> Sure. <S> Whether the aircraft is still on the runway or already airborne when it reaches the airspeed necessary for sufficient lift without flaps is rather irrelevant. <A> The Fokker 70 and Fokker 100 take off with no flaps even on short runways. <A> Flaps are a drag device. <S> Airlines have toyed with the idea of no flap takeoffs for a while. <S> You simply need higher airspeed for liftoff. <S> It is completely safe with the correct speed....usually 3-15 knots faster depending on airframe.
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The Airbus A300 and Boeing 767 are approved for such take-offs and it is being done regularly.
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What was the inflight entertainment in the early seventies? In her 1970 song "This Flight Tonight", Joni Mitchell sings I'm drinking sweet champagne Got the headphones up high Can't numb you out Can't drum you out of my mind They're playing Goodbye baby, Baby Goodbye Ooh ooh love is blind The Sony Walkman first came out near the end of that decade. So what was Joni listening to on that fateful flight? I will award a 100 point bonus to anyone who can identify the plane she was on in the song based on the lyrics. <Q> During that time, the in-flight entertainment mostly available on flights was radio 1 and/or TVs. <S> Although it was not on all flights. <S> Oops, that is true even today. <S> The radios may or may not have channels. <S> If they had, there was a knob on the armrest, next to headset jacks, to switch channels. <S> The headsets were pneumatic units like this: <S> The first time a movie was shown on an international flight was in 1962 by PIA . <S> It was more like the picture below but instead of LCD monitors, there were CRTs. <S> In mid-seventies, Braniff Airways was the first airline to offer video games in-flight . <S> By 1979, electronic headsets replaced their pneumatic counterparts, which improved audio quality. <S> Wikipedia has a detailed article about the history of in-flight entertainment: <S> In 1971, TRANSCOM developed the 8mm film cassette. <S> Flight attendants could now change movies in-flight and add short subject programming. <S> In the late 1970s and early 1980s, CRT-based projectors began to appear on newer widebody aircraft, such as the Boeing 767. <S> This website has nice slideshow about the history. <S> 1 <S> : Not actually a radio, but recorded audio <A> There would be a number of channels of pre-recorded 'radio'-type shows, typically 5 or 6 if I recall correctly, such as current affairs, comedy, classical music, easy-listening & pop/rock, plus the movie channel or channels. <S> Some airlines charged a nominal rental for the headsets, while others provided them in the plastic-wrapped 'travel pack' of blanket and pillow/cushion. <S> Either way, they were gathered up before landing. <S> The earliest headsets were pneumatic, but later there were electronic ones, albeit with connectors that were pretty much exclusive to airline travel, to discourage them going astray. <A> I remember flying on planes in the late 70's/early 80's, where there were headphone jacks built into the armrests. <S> But they weren't electronic jacks; the headphones were connected by rubber tubing, and the speakers were actually in the armrest, so the sound was conducted up the rubber tubing to the earpiece. <S> It made the headphones extremely cheap: they were just molded plastic and rubber tubing. <A> This is slightly off-topic because it is more about video than sound, however In Flight Entertainment, a Quick Look at its History <S> says, The popularity of in-flight entertainment didn’t really take off until 1960 with the invention of a smaller, more portable film playing system that would play smaller 16 mm reels . <S> Soon after, the invention of the pneumatic headset would finally resolve the problem of being able to hear over the loud cabin noises. <S> TWA became the first major airline to use the new system boosting them to become the world’s premiere airline to travel on. <S> The addition of the 8 mm cassette in 1971 made in-flight entertainment a more efficient process, mainly for the flight attendants who could simply change the film during the flight. <S> The video cassette would dominate the way passengers viewed in-flight films until the invention of the DVD which would later become the primary source of all in-flight movies. <S> Throughout the late 1970s and into the early 1980s, the CRT based projectors <S> began appearing on some wide body airliners. <S> The CRT projector used electric beams of colored light that would beam films onto a fluorescent screen. <S> The CRT was able to display a larger, clearer picture using both video cassettes and laser discs.
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The in-flight movies were shown using one or more common CRT TVs mounted on ceilings or walls and audio could be heard using the headsets.
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What is this component in an Airbus cockpit? I have noticed that on a lot (all?) Airbus cockpits, there are these "things" (for lack of a better term) under the panel. I have highlighted them in this picture of an A340 cockpit: What are they? <Q> Since Airbus planes use a sidestick instead of the traditional center yoke, they use the space where the yoke would be to include a fold out table instead. <S> You can see a laptop on one here . <S> The A380 version also has a keyboard. <S> This is used to interface with the onboard systems and input information . <A> The centre bit is the pull out mechanism for the table, the two bits either side are fold down footrests. <A> Are you talking about this area? <S> It is part of a standard laptop computer. <S> However, its integrated Keyboard Cursor Control Unit (KCCU) can interact with the cockpit screens. <S> The full-size keyboard felt substantial and, in the paperless cockpit, will greatly ease the tasks of data and text entry.
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This is a pull out keyboard, which is part of Electronic flight bag (EFB) .
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Are the aircraft used for the A380 display ready to be delivered to airlines? For displays in international airshow, Airbus uses A380 whose livery is the one of customers. Here are some examples: Le Bourget 2011 : Korean Air Farnborough 2012 : Malaysian Airline Le Bourget 2013 : British Airways Are those aircraft regular newly built aircraft ready to be delivered to airlines (with all the seats and passenger equipment inside)? Are those aircraft specially prepared? <Q> Installing interiors and seats is a regular part of the production process, and it's unlikely that the plane would be pulled from the line before seats are installed, and worked back in later. <S> From looking at rollout and delivery dates , these aircraft all had about 7 months between rollout and delivery, with the air show appearance happening within a month of delivery. <S> Also, the aircraft are used as static displays while not flying, allowing people to walk through and see the interior. <S> In 2011, the Korean Air A380 indeed had seats in it . <S> It was delivered in the middle of July. <S> In 2012, the Malaysian A380 also had seats installed . <S> It was delivered at the end of July. <S> In 2013, the British Airways A380 probably had seats installed. <S> I can't find any pictures of the inside, but it was delivered shortly after in early July . <S> Airbus also tends to bring a flight test A380 like MSN001 (first to fly, registered F-WWOW) for display, and has a more unusual interior . <S> The Korean Air A380 was used for the display in 2011 after the flight test plane MSN004 had a bit of a mishap . <A> Are those aircraft regular newly built aircraft ready to be delivered to airlines <S> Yes. <S> At least in the case of the aircraft in BA livery at the Paris airshow. <S> From other photos taken at that event, it had registration F-WWSK and construction number 095 BA registered it as G-XLEA . <S> That was listed as delivered 4 July <S> so almost certainly fully completed ready for BA when at the airshow on 17th June. <A> In the early days of A380 only prototypes were available, flying from airshow to airshow, each time with a livery of national company of the place. <S> They used giant adhesive films from Adhetec ( 13880 film series (pdf)).
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In all cases the answer is yes, those aircraft were all outfitted with seats, and at least very close to being ready for delivery to the customer.
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Can I get a photo with the pilots? Could I, as a passenger, get a picture with the pilots in the cockpit before takeoff/after landing? I'm asking specifically about any rules that would deny a passenger into the cockpit. I know this is too broad and subject to change from airline to airline, but generally would I be allowed? What about domestic vs international flights? <Q> When I feel the need to see the cockpit or discuss things with the pilots I try to ask the flightcrew before take-off if I can meet them after the flight. <S> Sometimes I explain my interests to the cabin crew and often they will arrange the visit. <S> In a few cases I just asked while deboarding. <S> Depending on the aircraft type and airport situation you have to think about the logistics a bit. <S> In single aisle aircraft, if you start a discussion with crew while deboarding, you are blocking the queue. <S> This gives the feeling that it is an inconvenient moment and reduces your chances. <S> So if you ask at the last possible moment, make sure most people already exited before you. <S> However, if passengers are transported to the terminal by bus, you will be holding the bus since you are the last to get off. <S> This reduces the time you can spend in cockpit drastically. <S> If you expect to be bussed to the terminal, ask cabin crew before the descent and don't wait until everybody has exited. <A> If you were going to try to do something like that, it would depend greatly on the crew . <S> You may be limited to getting the picture taken in the doorway to the cockpit, and for the sake of security, I would suggest after landing (generally when the pilots are doing their, "Bye, thanks for flying" thing as people deplane). <S> You would probably have to coordiante with the flightcrew, and make sure you are not impeeding progress of other passengers. <S> Furthermore, if you do it, others may want to do the same, so again, that may factor into the decision. <S> If you are going to try, I would suggest doing it on an airline that has a reputation for being more "fun" (like Southwest). <S> Also, many airlines have a sort of "public affairs" line that you can call and try to pre-coordiante such activity. <A> As you have said, cockpit entry rules vary depending on the country and even airline. <S> Airlines may have their own rules surrounding entry though. <S> I haven't tried in the US, but elsewhere I find that heading to the cockpit as really depends on the crew members and workload. <S> Before or after a short flight with a quick turnaround the pilots may rightly say they are too busy. <S> After a long international flight they may just want to get to their hotel! <S> I suggest that in cruise, when the FAs don't look too busy, just politely ask one of them if it would be possible to visit after the flight - explain that you're an enthusiast, etc. <S> It'll help if you've got a kid with you! <S> Hopefully the FA will ask the flight crew and you'll get a positive answer. <S> If you're really lucky (and in the right part of the world) you might even get an in-flight invite! <S> Remember that pilots are real people. <S> Most of them quite enjoy showing off their office to excited people when their circumstances permit.
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In the US visitors are fobidden from being in the cockpit when the aircraft is in flight, but to my knowledge it is still legally permissible when parked at the gate. I don't know about the situation specifically in the US, but in my - mostly European - experience crew are happy to welcome you to their office after flight.
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How reliable are stick shakers? I've read many accident reports, and seen reconstructions, where instrument failures, disagreeing sensor sources and auto pilot faults have led pilots into believing that they are over speeding when they are not (think AF447), are descending when they are actually climbing etc. It seems that in all cases where this has led to a stall, the stick shaker has activated but the PF does not take the correct immediate action for stalls, instead continuing to believe the erroneous information they are being fed. I understand the psychology of why this might be but is does strike me that many lives would have been saved if power up nose down had been applied. I've not found a case yet where the shaker was wrong. This leads me to wonder... How reliable are stick shakers? Should they always be trusted? Some older types even had an automatic stick pusher but this does not seem to be present in modern designs. Is this a consequence of shakers not being infallible? <Q> The Australian Transport Safety Bureau recently published a comprehensive research paper on reported stall warnings in high capacity aircraft - http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx <S> The report says that 30% of all stall warnings were false. <S> Note that stall warnings aren't limited to the stick shaker. <S> The report says that of all reported stick shaker events, 16% were false warnings. <S> Have a read of it, you'll find lots of interesting bits of information. <A> How reliable are stick shakers? <S> Should they always be trusted? <S> This is drilled into you when learning to fly on instruments. <S> Pilots very rarely rely solely on one source of information. <S> If you get a stick shaker, you'll normally immediately look for the reason as part of your scan. <S> Stall warnings are rare in large aircraft but you sometimes get transient warning, e.g. when an aircraft is in turbulence or at low speed with a higher angle of attack and manoeuvring. <S> The crew of AF447 had a number of conflicting indications in the flight deck and were relying on the protection system of the aircraft to prevent the stall. <S> Sadly the aircraft ended up stalled as the protection systems were not functioning correctly due to an erroneous air data source. <S> One of the pilots held positive back pressure on the controls which maintained the stall condition of the aircraft. <S> The recovery from the stall in large aircraft is the same as any with the most important part - Lower the nose . <S> Good article by Boeing here <S> Stick pushers are rare now as aircraft designers tend to shy away from producing aircraft which require one. <S> Aircraft such as the HS Trident had stick pushers as they could end up in a deep stall - which is unrecoverable flight condition. <A> I'm going to lump stick shakers with all stall warning devices as they all have the same purpose. <S> Stall warning devices are extremely reliable, and often more reliable than many pilots' judgement. <S> When they go off it is because the conditions for a stall exist, and action should be taken. <S> Occasionally a stall warning will go off momentarily in level flight because of turbulence, that usually is so short no action could be taken before the warning goes away. <S> Humans often have trouble in re-evaluating situations and can become fixated on one theory of events, especially under stress. <S> People like to have confidence in their beliefs and judgement which leads to confirmation bias , where people "cherry pick" details which fit their model of events. <S> This can lead people to ignore information that is literally in their face, as in AF447, Northwest 6231, and other similar accidents. <S> The airplane can be shouting "STALL! <S> STALL!", with an air horn blaring, stick shaker vibrating the pilot's hands until numb and the pilot will still be wondering why there's a high rate of descent. <S> So always trust your stall warning. <S> Personally (I'm a light aircraft, not a commercial pilot) <S> I practice stall recovery often where I immediately recover on the buzzer/horn, I do this so that it will become an instinctive reaction which I will do even if I'm overloaded and confused.
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I think the answer to this is can be covered by one of the great aviation mantras: "always trust your instruments"
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During which part of the flight the effect of air resistance is more important? Her teacher asked this question to my niece (8 years old)? However I couldn't find a solid answer either. In which part of the flight, the effect of the air resistance (drag) is more important? Takeoff, cruise, descent or landing? <Q> The answer they are looking for is probably cruise . <S> This is generally the longest part of the flight, so the losses from drag will add up. <S> Most aircraft are optimized as much as possible to have good performance in cruise to save fuel and meet range requirements, so having low drag is more important in this part of the flight than others. <S> This is also generally the section where the aircraft is traveling fastest. <S> As Peter Kämpf showed , drag is highest at higher speeds, other than periods where landing gear, flaps, etc., are extended and add more drag. <S> As Jay Carr explained , drag is important at every point while the aircraft is in the air, affecting different areas of performance. <S> During takeoff, drag will affect the runway distance needed, and initial climb performance. <S> Low drag during descent is helpful, unless you need to get down faster, like in an emergency descent. <S> Drag is probably highest during landing, because the emphasis is placed on having as much lift as possible at slower landing speeds, and this lift is created at the expense of higher drag. <A> The question leaves a lot of room for interpretation, so here is my version: <S> If we assume a constant mass of the aircraft, resistance varies with speed, and there is a minimum relative to the lift force when the lift-induced and zero-lift drag components are equally large. <S> You can now argue that air resistance (however defined) is least important at that speed and becomes more important at low and high speed. <S> The plot shows the drag components of a typical glider in straight flight, but if you adapt speeds and forces, the same plot works for any other airplane. <S> It shows that the drag (= air resistance) is highest at the highest flight speed. <A> Anytime air is moving over the surfaces of the aircraft, drag is important. <S> There really isn't a time when it's "more" important. <S> When an aircraft wants to move, during any phase of flight, the thrust of the craft must exceed the drag the air (or wheels, on the ground) is creating on the craft. <S> At any point that the aircraft is flying, the drag must be overcome to the point that the wings can create the required lift to get the aircraft into the sky. <S> Perhaps, though, the question actually had to do with air brakes ? <S> When those are deployed the amount of drag created is increased by quite a lot, slowing the aircraft by quite a bit. <S> And as a result air brakes are often used during the descent phase of flight in order to keep the plane from accelerating to much as it approaches the runway. <S> Perhaps that's what the teacher is after... <A> I would pick landing as my favourite for the answer and as it is the most apparent, with all the bits of metal hanging from the aircraft. <S> As the aircraft slows it lowers the leading edge slats(if fitted) and trailing edge flaps to increase the amount of lift the wing is able to produce, as you increase the lift you are also increasing the drag. <S> In jet aircraft the spoilers are often used to assist this reduction in speed or to maintain/increase the rate of descent whilst decelerating(not easy in a heavy jet with lots of inertia). <S> At some point during the approaching (normally around 2000ft ish) you have to lower the gear, which again adds to the drag. <S> All this drag on approach allows the engines to spool up, which is useful on large turbine aircraft as it means the engine is at a good state to provide power quickly in the event of a missed approach. <S> On touch down the configuration changes again - the spoilers deploy, reverse is selected and as the nose lowers <S> the wheel brakes kick in - lots of drag (ok, the wheel brakes don't provide air resistance, but they are a fairly large part of the decel process). <S> The spoilers drastically reduce the lift of the wing pushing the aircraft down onto runway meaning the brakes have the greatest effect. <S> Some aircraft at this point change the flap configuration, in light aircraft its an option to retract the flap which reduces the lift on the wing making the brakes more effective. <S> Other types lower more flap, having a "barn door" type effect. <S> The Boeing 747 retracts the inboard section of slat, which again helps reduce the lift on the largest part of the wing. <S> As all this is happening thrust is redirected forward and power is increased on the engines helping the deceleration down to around 80-60kts. <S> In some aircraft (normally fighters) <S> you hold the nose off the runway on landing to increase drag, braking aerodynamically down to a low speed. <S> In commercial aircraft you normally lower the nose as the wheel brakes have greater effect (you normally have a lot more main wheels/brake units than fighter types).
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Drag (Air resistance) plays a part in all phases of flight, its most critical during takeoff or landing as this is when it will have the most drastic/immediate effect.
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How does flying with flaps differ from flying with airbrakes? I've got a private pilot license and learned on a Scheibe Falke SF25 . For the last year however I've only been flying a C42 Ultralight . I find flying the UL way easier for one particular reason: it has flaps where the Falke has just airbrakes. I don't know how many hundred landings on the Falke I have done, still I have never felt comfortable. The reason is the airbrake. For some reason it scares me. With the UL I set the speed, lower the flaps and if I'm too far away I can add a little power. The flaps lower the stall speed and make the plane slower. The airbrakes also make the plane slower, however they increase the stall speed. I see how (especially flight instructors) pull the air brake to the maximum and then do their approach. If I'm too far away with the Falke, I have to retract the air brakes. This affects the plane very directly, especially compared to adding a little power on the UL. My questions are: How to correctly land a plane with airbrakes? Full out or just a bit? Do you leave them in one position or do you vary during approach? How much do they really affect stall speed? <Q> The SF-25 has such a low wing loading that it easily tolerates the small reduction in maximum lift which the airbrakes cause. <S> I have done very few flights in it <S> (I'm too tall to fit comfortably in <S> it's cramped cockpit), but from what I remember the airbrakes are not very big, having little effect on minimum speed. <S> My experience, however, is with the SF-25 B, and you linked to the SF-25 C, so I have to assume that my experience is not fully relevant. <S> I have more experience with real gliders and composite motorgliders, and here my experience is: <S> Start your approach, stabilize the right approach speed, set the airbrakes such that your glide path looks right and do not play around with them too much. <S> Set your approach such that you need medium airbrake extension, so you have margin for corrections in both directions. <S> Normally, I come in a little high so I am not caught by windshear, and <S> when I am sure I will reach the intended touchdown point, I extend the airbrakes fully to land with the shortest distance possible. <S> However, when touching down, make sure you do not fully extend the airbrakes: This gives you more time for stopping the descent. <S> Especially in gliders with very effective flaps and airbrakes <S> ( ASW-20 C , ASH-25 ) <S> I never made a good landing with fully extended airbrakes. <S> Reduce them to half extension at the most when touching down! <S> In the ASW gliders the airbrakes are linked to the very effective wheel brake, and touching down with fully deployed airbrakes means that the wheel is braked at touchdown. <S> This is another reason to reduce airbrake extension when touching down. <S> In high-performance gliders it is easy to float too long, so it is very important to control your approach speed and to continue the descent all the way down to the touchdown point. <S> Don't pull too early! <S> The SF-25 will not float as much, but with its low wing it shows a pronounced ground effect, and exercising strict discipline when landing helps a lot to make the landing better. <S> I could not find a number for the stall speed change due to airbrakes in the SF-25 manual , but I would guess it is at most a few km/h. <A> I would not recommend flying an approach to land with maximum airbrakes. <S> Instead, what I was taught to do in a glider (or a motor-glider without the engine running) is to plan and fly the approach with about 1/2 airbrake extension. <S> This allows you to use the airbrake handle much like you would use the throttle in an aircraft with a running engine: Getting a little low or slow - Retract the airbrakes as far as needed to return to your normal approach angle. <S> Getting a little high or fast - Extend the airbrakes as far as needed to return to your normal approach angle. <S> You then touch down with whatever airbrake extension was required, and then fully extend them afterwards. <S> Flaps are unrelated to airbrakes, and you can have gliders with or without either of them. <S> Some gliders have both! <S> This is important in high performance gliders because it can be very hard to actually make them go down without gaining speed when you want to land. <S> As far as how much they affect the stall speed, this is very much dependant upon the specific aircraft and the design of the airbrakes/wing. <S> The POH should describe any special procedures (such as flying your approach speed + 10 with full airbrake extension) if they are needed. <A> It's bad to compare flaps and speed brakes and use flaps as brakes. <S> They are meant for different things. <S> To slow down and to make stall speed slower. <S> Of course it's possible to use flaps as speed brakes but it's a bad practice. <S> Boeing 737 flight manual warn's pilots not to use flaps to slow down. <S> High performance aircraft usually has both. <S> Another important think is that speed brakes doesn't have speed limit. <S> Flaps have speed schedule and are meant only for slow speed. <S> For example you want to descent <S> fast you maintain maximum speed and extend brakes. <A> Flaps and spoilers(airbrakes) have a similar affect by creating more drag. <S> However, they have the opposite affect when it comes to creating lift. <S> A great way to think of this is the car analogy. <S> There are two ways to slow down a car: the hydraulic brakes and the engine brakes. <S> Hydraulic brakes, analogous to spoilers/airbrakes, decreases revs as it slows down the vehicle. <S> On a standard transmission, applying the brakes without hitting the clutch will eventually cause revs to go to low and stall the car. <S> Similarly on an aircraft, using spoilers will increase the angle of attack(decrease lift) and of course increase stall speeds. <S> Conversely, flaps work like engine brakes. <S> If I'm cruising at 50 mph(80 km/h) and my revs are at 1500 rpm in 6th, and I put my car in 5th while maintaining the same speed, I will have to increase the power I put and my revs will jump to about 2000. <S> SAME CONCEPT IN AN AIRCRAFT! <S> If I'm cruising at 180 knots IAS and my angle of attack is 10 degrees, and I apply flaps from up to 10 degrees, the engine will have to use more power to maintain 180 knots IAS, but my angle of attack will decrease, and I'll get more lift. <S> Just like a car has speed limits for its gears, aircrafts have maximum speeds to use every level of flaps. <S> Using engine brakes can help you slow down just like flaps <S> can help you fly at a lower speed and eventually land at an optimal speed.
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The flaps allow you to slow further, which reduces your ground roll and also increases drag.
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How do Throttle control and Propeller control work together? I haven't been able to understand. If propeller control controls the pitch of the blades in a constant speed engine, what do the throttle control do? I've seen (in some normal operation manuals for some planes) that you have a Torque limit and control the Torque with the throttle control, and the RPM with the Propeller Control, but, if the propeller is spinning always at the same speed and the blades are positioned at the same pitch how can the throttle reduce or increase thrust? <Q> In a constant speed prop, the prop control lever basically changes the speed of the prop (it is not always running at the same speed as you indicate in your question, but rather once the speed is changed by the prop control lever, the governor keeps it at that speed). <S> If power (or airspeed) is changed, the blade angle will automatically change in order to keep the prop turning at the same speed (within the limits that it is designed for). <S> Since adding power would normally increase the speed of the prop, the governor automatically changes the blade angle in order to keep it at the same speed. <S> The same is true when power is reduced or airspeed is changed. <S> Thrust is changed by engine power because, even though the prop is turning at the same speed, the angle of attack of the prop has been changed, which changes the amount of thrust. <S> For more general information about how a constant speed prop works, see this question and answers: <S> How does a Constant Speed Propeller Work? <A> First and foremost, speed of the propeller does not govern the thrust it is producing. <S> It only limits it from above. <S> The faster the propeller turns the more thrust it can provide, but it can produce less depending on power the engine supplies. <S> With engine at idle, the propeller produces drag only and at higher rpm it produces more drag. <S> Next engine speed (and aircraft have fixed gear, so engine speed is proportional to propeller speed) does not govern the power it provides either, but also only limits it from above. <S> The engine can only produce this amount of power per revolution, but if you restrict the fuel or fuel-air mixture flow into the engine, it will produce less. <S> Consider coasting at high speed in a car with gear on. <S> The engine turns at high rpm, because it is connected to the turning wheels, but with accelerator released it does not produce any power and the car is slowing down. <S> The same happens in aircraft. <S> At idle the propeller windmills by oncoming air and cranks the engine, but because that produces no power, the net effect is decelerating. <S> The throttle restricts flow of fuel-air mixture in the engine and is therefore the main control of engine power. " <S> So why don't you always run the propeller at the maximum rpm? <S> Higher rpm increases wear on the engine. <S> So usually high rpm is used for take-off where maximum power is needed, then rpm is reduced to recommended cruise value to reduce wear of the engine and for landing high rpm is selected again to increase drag of windmilling to slow down and to have full power available in case of go around. <A> The throttle controls the engine power. <S> In most engines (car, lawnmower etc.) this also controls the RPM. <S> The prop control adjusts the pitch of the prop blades and thus the load on the engine, so the RPM stays the same (hence: "constant speed") but it will fall off speed if there isn't enough power. <S> And it's a "constant speed PROP", not a "constant speed engine" <A> When you run up the engine before takeoff, you exercise the prop control. <S> At a fixed throttle setting, move the control from "high rpm" to "low rpm". <S> The prop blades will take a bigger "bite" on the air, and even though the engine is still producing about the same HP, the rpm will slow way down. <S> It's a case of torque increasing due to the aero loading, and rpm decreasing because of the torque. <S> Remember: high rpm = <S> low pitch, and low rpm = <S> high pitch. <S> The Brits say it a little differently: high rpm = fine pitch, and low rpm = coarse pitch. <S> (This is analogous to a fine or coarse pitch on a screw)
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Throttle" really means the restriction flap in carburettor, so in diesel and turbine engines where fuel flow is controlled instead the lever is called a "power" or "thrust" lever.
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How much does it cost to learn to fly in the UK, and what restrictions are there? Flying has been a dream for me since I was a little boy. My absolute dream career was to be a fighter pilot in the RAF. It's obviously a very hard career to get into, however I fell even before the first hurdle when I found out that I'm colour blind. Finding out I was colour blind actually closed a lot of potentially enjoyable careers. Police, Armed Forces, Electrical all reject colour blind people. I'd love to be able to fly, freely in a light aircraft - something like a glider or mosquito helicopter, but I just can't figure out where I need to start. Also, I'm not sure if it's financially viable. Could someone give me a breakdown of costs and commitments needed? Also, I'm assuming that being colour blind doesn't automatically mean I'm not able to fly? Also, I'm in the UK <Q> My recommendation is: Join a glider club. <S> This limits the expense and puts you into contact with many like-minded people. <S> Make sure the club has several gliding instructors, so you will have enough chance for training lessons. <S> Did you try the UK gliding club finder <S> yet? <S> I prefer gliders over powered aircraft because they expose you to the weather and the laws of aerodynamics much more directly. <S> Also, the expenses per hour are much lower. <A> There are a number of ways to 'get in the air'. <S> Peter's mention of gliding is a good one. <S> The requirements to get a glider license are substantially lower than any of the routes to a powered license. <S> However it has obvious restrictions on weather, distance passengers etc. <S> Time spent flying a glider will not count towards your requirements for a powered license if you decide to get one (though obviously many of the skills are transferrable). <S> Gliding is also cheaper than other forms of aviation. <S> The next easiest way to get into the air is through a microlight permit. <S> That's slightly more regulated than a glider, with slightly higher requirements, but also has restrictions on speed, passengers distance, weather, comfort etc. <S> The route with the highest requirements to get qualified, and also the highest cost, is the private pilots license. <S> However that will get you the ability to fly an aircraft with a much higher comfort, capability and performance level. <S> It's also opens up the route to more certifications - twin engines, instrument flying, commercial flying and even airlines (technically you can be a commercial glider or microlight pilot, but it's much rarer). <S> Only you can decide which route you prefer, taking into account all the factors. <S> The best way to find out about how you could achieve each one is to visit a club or a school where they do each . <S> There are flying clubs or schools at virtually every working airport, and the internet will give you a list of glider or microlight clubs. <A> From my reading of this ( https://www.caa.co.uk/default.aspx?catid=49&pagetype=90&pageid=13879 ), colour-blindness means you can't get a class 1 (commercial) medical, but can get a class 2 (private) with a restriction that bars you from night flying. <S> I'm neither a medic nor colour-blind though <S> so I'd definitely recommend you get in touch with an AME (authorised medical examiner, who you'll need to see anyway before going solo) to check before you pay for much training! <S> Costs for a full PPL... depends a lot on area, school, airport etc <S> but you might be looking at something approaching £10k. <S> That's £150/hr for a cheap plane, £30/hr for an instructor, and let's call it 50 hours (45 minimum + the exam + some leeway) to get 9k. <S> Then 9 ground exams @ £25 = 225, and new study guides which are about £120 <S> (I got mine 2nd hand from eBay for about £40 but <S> the syllabus has changed; I've no idea <S> how much). <S> Initial medical exam is around £200, skills test around £170, CAA admin another £180. <S> Oh, and your flying school may want a membership fee, let's say £100/year. <S> That's, what, £9975? <S> I've taken a few shortcuts (e.g. maybe you won't need 50hrs <S> and I've ignored cheap stuff like a logbook, kneeboard, ruler marked in nm) <S> but £10k seems reasonable to me as a rough estimate. <S> I've also ignored landing fees. <S> My local fees were included but you'll need a few land-aways (at least 4?) <S> at £10-20 each. <S> Beware of the "local fees" thing... <S> I've spoken to people who found much cheaper lessons elsewhere, but they didn't include any landing fees. <S> I reckon I booked <S> at least 100 landings/touch&gos during my PPL, which would have made that "cheap" rate a lot less appealing.
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At most clubs, you can expect to pay around £20 per hour to hire a glider, around £30 for an aerotow launch and around £8 for a winch launch.
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Can rotorcraft pick up a dangerous electric charge? So, I was re-watching The Hunt For Red October, (in light of current Russian shenanigans with Sweden), and there was a scene in which a crew-member on the ground was electrocuted by making contact (and presumably grounding) the helicopter, which had picked up a charge in the stormy weather. Can anyone explain more of what is going on here? <Q> From a 1962 US Army document: Any aircraft flying in the atmosphere can be considered as a conductive body located in a highly electrically insulated environment. <S> In such a body, electrostatic charge is generated by three principal mechanisms: <S> Charge transfer created by a triboelectric effect between the aircraft and the atmospheric particles, such as dust, water, water vapor, snow, etc. <S> Unbalance of the ionic content of the exhaust gases produced by the aircraft <S> engine(s). <S> Induction charge due to high electrostaticfield gradients which are found occasionally in the aircraft flight path. <S> Source <S> Here's a more detailed photo of the US army discharging a helicopter while wearing insulating gloves: <S> SGT Nathan Rodeheaven uses a static probe to discharge static electricity from a UH-60 Black Hawk before his teammate, PV2 Danny Browning, hooks up the cargo to the helicopter. <S> The safety measure prevents the hook-up man from being electrocuted in the event there is accumulated static electricity. <S> Photo: <S> Kristin Molinaro <A> I am a Naval Aviator and as part of my water survival training, I was deposited by boat off the coast of Florida and picked up by helicopter. <S> It was a huge point of emphasis that we let the helicopter's rescue hook touch the water to discharge any built up static before we touched it. <S> No one in my class grabbed it before it hit the water, so I can't speak to how bad the shock would have been. <A> I work for a Christmas tree farm and we harvest our trees out of the field using a helicopter. <S> I am the hook man and attach the bundle of trees to the heli, then he takes them to another location. <S> In that breif trip during a rain storm, or even a foggy day static charge will build resulting in a very unpleasant shock. <S> Sometimes bad enough it will contract the muscles in my hand and arm. <S> I’ve been doing this for 3 years and finally invested in some 20,000Vac insulated gloves that are enough to keep this from happening. <A> Helicopters in normal weather will build up a static charge, just ask any ground crew for a logging helicopter. <S> Normally the hook will be grounded by dropping it on the ground before the hooker will touch it. <S> Or a grounding rod will be used to neutralize the static charge. <A> I was struck in the forehead in 1983 from the discharge off a CH-53. <S> I was wearing a kelvar helmet which was split down the middle from the strike, heart rate slowed down to 4 beats a minute thought I was a gone. <S> I was stationed at camp Pendleton USMC when it happened. <A> Yes they do. <S> I was involved in many HDSs (Helicopter Delivery Service) and would earth the Helo with a sheperds crook and trailing copper linkage - often getting a visible spark. <S> I also took part in the rescue of a few dozen (memory fades on how many) crew from a bombed ship with no hook and earthed the helo myself - yes it hurt. <A> We didn’t have a static hook in my day. <S> I will tell you, sometimes the pilots would relieve the static charge by grounding the aircraft themselves. <S> Sometimes, they did not. <S> The static charge would vary From moderate to severe. <S> And, it could even be felt by your partner who was bracing you by the legs. <S> After the first couple of volunteer troopers started flinching from the shock and throwing the hook, me and my buddy got elected/volunteered to do it. <S> We airmobiled the entire battery-sized unit, alternating back-and-forth as hook up man. <S> By the time it was done, we were completely spent LOL. <S> 82nd ABN 2/321 ,B /3-319 1986-89. <A> See, CAA CAP 426, Helicopter External Load Operations, April 2006 6.25 Electrical Static Charges and 6.26 Dissipation of Static Electricity and Appendix B Static Electricity Charging Conditions
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In the same way than an aircraft will build static charge on the wings from friction with the air, the same thing can happen with helicopters from fast moving blades.
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How are go-arounds safe with close parallel runways? Some airports operate simultaneous take off and landing on parallel but close runways. By close, I mean like the pairs of runways at LAX . What if a landing aircraft makes a go-around at the same time as another aircraft takes off? How is separation maintained? Would it be enough for the missed approach procedure to specify turning away from the departure runway? <Q> The first thing I would point out is that LAX isn't going to be running simultaneous approaches on 24L and 24R or 25L and 25R. <S> They'll select one of each of the parallel sets for the landing runways (typically the outer runways), and one of each for departing runways (typically the inner runways). <S> For example, they might be landing on 25L and 24R and departing 25R and 24L. <S> So, there's quite a bit of distance between those runways, and very little risk in a go around situation. <S> Here's a diagram illustrating LAX's typical arrival/departure runway usage to make it more visually apparent what I mean: <S> The second part of your question about an aircraft taking off at the same time as a go-around certainly happens, and when it does, ATC needs to take action to ensure safety and separation. <S> ATC separation requirements can be satisfied by altitude, distance, or divergence (and, in some cases, visual contact). <S> I believe the requirement is 30°, so tower would typically order a go-around and order a new heading at least 30° off of runway heading. <S> The geography of the area, layout of the airspace, and the approach patterns would likely dictate the exact procedure used at each airport since their two primary goals, in order, are going to be 1. safety, and 2. <S> getting them back in the approach sequence. <S> In the LAX example, a go-around on 24R would most likely get a right turn, and 25L would most likely get left turn (away from the airport) <S> so as not to conflict with other departing or arriving traffic. <S> This is one of a few reasons the outer runways are preferred for landing. <A> Adding some more information to Bret's answer: Take a look at both ILS approach charts for Munich's runways 26L and 26R 1 , which are parallel runwawys. <S> Both ILS instrument approaches terminate at the Missed Approach Point (MAPt) . <S> You can see from the charts that the Missed Approach for the northern runway 26R mandates a right turn to the MIKE (MIQ) NDB after passing 1.0 DME of the Munich (DMN) DME. <S> You can see from the charts that the Missed Approach for the southern runway 26L mandates a left turn to the Munich (MUN) VOR after passing 1.0 DME of the Munich (DMS) DME. <S> In the event that you have an arrival to the northern runway and a departure from the southern runway that would use a northern Standard Instrument Departure , such as the ANKER6S Departure , you could instruct the aircraft on the departure to maintain runway track or continue on a heading to establish separation between both aircraft. <S> Tower and Approach controllers develop a contingency plan when working with arrivals and departures in their head, which they can quickly deploy to establish and maintain separation by using standard procedures or vectors. <S> 1 <S> The source I am providing here is a simulation resource. <S> While the charts are as close to the real-world counterpart as possible, they are not to be used for real-world aviation, but will serve their purpose for visually supporting the answer and are easily accessible. <A> Also a big Problem exists at Zurich Airport where they must wait until a Landing on 14 is completed before they can give start-clearance on 16. <S> This is due to the problem if an Airplane wants to land on 14 must make a go-around and the plane on 16 starts simultaneous, a possibility of a conflict can occur in mid-air. <S> Edit clarification according to my comments: <S> Normal Route is that Airplanes taking of on RWY16 <S> (they changed it slightly on march 2014) <S> have to turn left, Zurich is famous that a plane taking off on RWY 16 will fly over the Airport at a much higher Attitude : Out of a Pilot Briefing: <S> All SID out of runway 16 describes shortly after airborne a left turn to avoid noise emissions over the city of Zurich. <S> This procedure often causes difficulties because it is hard to integrate in the FMS. <S> Therefore, we recommend you to fly that left turn manually or with the heading function of the autopilot. <S> Take caution to not turn right! <S> The SIDs out of runway 34 is more or less a long left turn and normally no problem for the FMS. <S> Stay on the Tower frequency until advised.
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In the situation you described, divergence is the quickest and safest way to achieve separation.
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What radio frequencies are used for intercom in formation flying? What radio frequencies are used for air-to-air intercom in formation flying? I assume there is a difference between military and civil aviation (e.g a group of GA aircrafts flying as a formation). I found a couple of civil UNICOM frequencies here (e.g. 122.8 MHz, 122.975 MHz, ...). 122.750 MHz (Aviation Air to Air Communications) seems to be what I am looking for (correct?). But what if there is more than one team? I also wonder if in military or professional formations (aerobatic formations) something outside the Very High Frequency (VHF) Aviation Band is used (to provide better quality, e.g. digital communication). In this article I can see lot of military frequencies, but not telling me what to use for military formation flying. <Q> For the US, according to section 4-1-11 of the AIM ( Designated UNICOM/MULTICOM Frequencies ) for private fixed-wing flights you should use 122.75: Air-to-air communication (private fixed wing aircraft): 122.750 Air-to-air communications (general aviation helicopters): 123.025 Aviation instruction, Glider, Hot Air Balloon (not to be used for advisory service): 123.300, 123.500 I have no idea what the military does and their tactical comms might even be encrypted anyway, but they frequently use UHF instead of VHF, at least in the US. <S> Nor do I know what to do if you have two formation flights at the same time, <S> but I guess that in reality it's either an air show with some form of semi-official control and perhaps even NOTAMs, or it's something private and in that case people make their own arrangements, e.g. picking some frequency that doesn't overlap with any nearby assigned frequencies. <S> Using 123.45 is apparently common, but definitely not official. <S> Non-VHF communications for private flights would be regulated by the FCC, not the FAA, and personally I'm not sure if the benefits would be worth the extra equipment and the risk of confusion, but then again I know nothing about formation flying. <S> There's some useful information from the FAA in this policy order clarifying the use of 121.5 and 123.45. <S> It says that 123.45 is for operational use in oceanic regions, and within the US <S> it's reserved for "non-government flight test operations". <S> There's also an FAA document on requesting temporary frequencies for airshows etc. <S> but it's air to ground only. <A> Military use UHF frequencies. <S> Each organization has a communication frequency for contact if you need to divert, have an emergency, or need guidance from higher authority. <S> When in formation, you have a tac frequency to talk to the other plane(s), but most communication of a non-tactical nature is done on traffic control frequencies. <S> ATC handles formations as a single flight. <S> Each member of the flight has a number Lead(1), 2, 3, etc. <S> Lead does all communications with ATC. <S> If you are directed to (for example, change altitude, the lead plane acknowledges with call sign and climbing to flight level 240 (if you are lower and going to 24,000 feet MSL. <S> The number two aircraft just responds "2" and the number 3 "3" and so on. <S> If you do not have a tac frequency and you need to have a conversation with another plane, you tell them to go to an informal channel like Winchester or popcorn. <S> Winchester is 303.0. <S> These informal channels were used extensively in Viet Nam to discuss what idiots the brass were. <S> Pilots had a code sheet that had a code for common expressions. <A> For general aviation, 122.75 is the official fixed wing air-to-air frequency designated by the FCC and FAA (and 123.025 is for helicopters). <S> Otherwise, you should probably ask around in the area in which you plan to operate. <S> See if there is a frequency that is commonly used. <S> This thread mentions a few frequencies people have used. <S> If you can find the frequencies used for a local air show, that could be a good indication of frequencies that would be free. <S> Military aviation is going to vary a lot more. <S> Typically UHF is used, but certainly VHF or digital could be used depending on the situation. <S> Refueling tracks have designated areas and frequencies. <S> Performing groups have a set of channels that they use when they fly. <S> For regular formation flying though, it will probably vary more. <S> RadioReference is a good place to look. <S> 123.45 is listed as "unofficial" air to air and flight test. <S> The military table lists 303.0 as a possibility. <A> With respect to military aviation, it's going to depend on the radio capabilities of the aircraft involved in the formation. <S> fooot's answer mentions that typically UHF is used. <S> That is sort of true - UHF is generally used for military ATC, RAPCON, etc, but as far as aircraft-to-aircraft, it will depend on the capabilities of the plane. <S> With smaller aircraft, such as trainers and fighters, they may only have 1 of each (UHF/VHF), so <S> with the need to monitor the controlling agency, that may drive the "formation frequency" to using a VHF. <S> With regards to specific channels in that article, it will vary from location to location, as different bases/squadrons/aircrafts will have different frequencies designated for formations. <S> So there's no real way to know "in general" - it would be a localism.
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Many large aircraft have multiple radios, UHF and VHF, as well as digital radios, so depending on the mission, they may use a specified area frequency, or a "local" frequency, or a specific military channel. There are also other frequencies allowed based on location (Hawaii, Los Angeles, and the Grand Canyon).
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What criteria does ATC apply to determine if an aircraft is established on the localizer if the pilot does not report it? How close in time or distance will ATC let a pilot fly to the localizer, before cancelling the approach clearance, where the pilot has not reported being established? Is it the controller's call when to cancel the clearance? <Q> Each instrument approach consists of a lateral part and a vertical part, in the case of the ILS approach these are: localizer and glideslope. <S> Aircraft are usually vectored to intercept the localizer approximately 1-2nm before the Final Approach Fix (FAF), where the glideslope is captured. <S> Aircraft can be vectored onto the localizer as far as 20-25nm out, depending on terrain, localizer equipment and many other factors. <S> If the aircraft is established on the localizer, it will try to intercept the glideslope, which is the vertical guidance system in the ILS approach. <S> For VOR/DME, LOC/DME, NDB/DME or RNAV approaches, the vertical guidance is either achieved through correlation of location to a specific altitude in the chart or technical means which do not require a glideslope. <S> If an aircraft passes the Final Approach Fix and does not seem to descend, it will be considered as not established and the approach clearance will be cancelled, instructing the aircraft to either follow the missed approach procedure or manually vectoring the aircraft for another approach. <A> I'm not 100% sure that I understand your question, but I think you're asking this: if a pilot is on a localizer or ILS approach but doesn't report established, when will ATC cancel his clearance and instruct him to go missed or vector him? <S> But you didn't clarify if the pilot is actually flying the approach correctly or not, where he started the approach, if he's being vectored, what his current clearance is etc. <S> so I'm not sure I understand the scenario. <S> Anyway, I couldn't find a definitive, objective answer to this <S> and I'd be surprised if there is one. <S> If a pilot deviates from an approach procedure in any way, then the controller has to make a judgement call based on current traffic, workload, terrain, student pilots etc. <S> and I think it's unlikely that there could be a single, definite rule on what to do when. <S> Apart from any other considerations, if the pilot doesn't report established it could be a comms failure and there are procedures for that: in this case since he was already cleared for the approach (presumably) the controller will expect him to continue. <S> And if the pilot deviates without comms, there isn't much the controller can do anyway apart from clear the surrounding airspace. <S> Having said that, the FAA procedures for controllers give this instruction for handling aircraft on a radar arrival - i.e. under direct ATC control - and it seems plausible that they would apply it in other cases too: b. <S> If deviations from the final approach course are observed after initial course interception, apply the following: Outside the approach gate: apply procedures in accordance with subpara a, if necessary, vector the aircraft for another approach. <S> Inside the approach gate: inform the pilot of the aircraft's position and ask intentions. <S> "subpara a" simply says that the controller should provide suitable vectors with a maximum 30° intercept angle to the final approach course. <S> The approach gate is defined in the P/CG: <S> APPROACH GATE - An imaginary point used within ATC as a basis for vectoring aircraft to the final approach course. <S> The gate will be established along the final approach course 1 mile from the final approach fix on the side away from the airport and will be no closer than 5 miles from the landing threshold. <A> The question doesn't make sense, because the clearance won't be issued until the aircraft is established on a published segment of the approach. <S> Nevertheless, I will try to explain how it works. <S> Note that the aircraft can only be given vectors to final if its on radar, and so the controller can see the aircraft's exact position. <S> The controller can't, however, tell if the localizer needle is alive and the frequency identified, so he asks "Report established." <S> It is only AFTER the aircraft is established on a published segment of the approach that the controller can say "You're 5 miles from MOXIE, cleared ILS 27 approach." <S> If the aircraft is outside the approach gate and can intercept another vector to final without requiring too sharp a turn, the controller will continue to provide vectors to final. <S> If the aircraft cannot be vectored from where it is, the controller will spin the aircraft back downwind or tell him to fly the missed, and give the pilot another shot at getting established. <S> If the aircraft is inside the approach gate, but deviating from the final approach course/localizer, the controller will say something like "3 miles from the airport <S> 1 mile right of course, say intentions," and the pilot can ask for vectors downwind and back around onto final. <S> He won't have his approach clearance terminated. <S> source: http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0509.html
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If an aircraft is not established on the localizer, there is no point in continuing the approach, so it will be cancelled and the aircraft revectored.
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Can civilians fly military aircraft? I saw a few videos of the Sukhoi Su-35 doing some amazing aerobatics and I was wondering if a civilian could ever fly one - either for aerobatics or just fly it as their personal jet. Obviously assume adequate training, fitness, budget, time etc. I assume you'll have to start on a jet trainer first, after you had already flown other smaller aircraft - but this is outside the scope of my question. There is a question that suggests civilians can buy military aircraft, but it doesn't explicitly say whether they can actually fly them. One comment seems to suggest they can't , although it's not very clear. <Q> I'm not sure if you're asking about flying such an aircraft (e.g. renting one) or owning one. <S> But either way the answer is yes. <S> I've flown a Hawker Hunter at a (now-defunct) location in Cape Town on a mixed low-level/acrobatic flight along the coast. <S> There were no restrictions on who could fly in the aircraft apart from the obvious ones (no kids; must have reasonable height/weight and general fitness) <S> but they didn't let non-pilots take the controls. <S> We did some aerobatics (up to 5G, from memory) and I had the controls in cruise flight for about 10 minutes. <S> There was absolutely nothing that a civilian couldn't learn: it's 'just' another aircraft. <S> As for owning one, it's not uncommon at all. <S> Privately owned ex-military aircraft are often referred to as " warbirds " and in the US there's even an EAA organization for owners. <S> The aircraft are usually considered experimental (or the local equivalent) for the purposes of regulation and airworthiness. <S> The barriers to owning these aircraft are (as always) money and training. <S> Buying and maintaining them is very expensive because there are so few parts or mechanics available, and insuring them is (almost) impossible so most owners have to self-insure. <S> The operating costs are also usually high, especially if the aircraft systems need 'exotic' fuels, gases, lubricants or other consumables. <S> You may need to include explosives on the list, in the case of ejection seats. <S> Training is a similar issue because so few people can instruct you in how to fly a military aircraft, but obviously this isn't a total barrier <S> and I assume that if you're involved in that part of the flying community then you'll find the contacts you need. <S> But for most people that's a lot of 'ifs' :-) <A> I have flown an L-39 military trainer that a local FBO was renting time in. <S> Lots of fun, but not something you want to fly any distance. <S> This place will give you an orientation ride and work with you on getting your LOA if you are interested in buying and flying a jet warbird. <S> There also was an outfit in one of the former Soviet countries that would give your rides in more modern Migs like the Mig-29. <A> The test pilots of military aircraft manufacturers are also civilians flying military aircraft. <S> They perform among others checkout flights before delivery or after repair of every single military aircraft. <S> Usually they are former military pilots. <A> Yes, civilians can fly military aircraft including jets. <S> The Czech's have sold off a lot of their old L-39 trainers and you frequently see them around airfields. <S> I know of one accident where the L-39's nose, which normally carries a radar, had been converted into a luggage compartment and the hatch opened as the guy was taking off and one of his suitcases flew into the left engine with fatal consequences. <S> The biggest headache is the ejection seat which is a maintenance nightmare with various legal issues. <S> Also, military jets tend to burn fuel like a son-of-a-bitch, so they can be expensive to fly. <S> One of my dreams is to someday own a Texan , which would be so cool (think: cruising at 300 knots, wowzers!). <S> Hopefully, Greece will go bankrupt and have to sell off all their Texans cheap, hee hee.
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So in general, if you can buy a military aircraft legally in your country, if you have enough money for operations and maintenance, if you can find someone to train you, and if you can comply with your local regulations on non-type (experimental) aircraft then you can absolutely do it.
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Is engine damage due to a fan blade failure irreparable? I have a question related to this question and this video . The question says that sometimes a fan blade failure can occur. My question now is, if a fan blade separates or a malfunction occurs, is the engine still repairable? I think the damage to the engine's structure would be quite high? According to the video a fan blade malfunction occurred on start-up, how could a malfunction appear on start-up? <Q> This depends on the failure: A fan blade can be damaged by birds, debris, or aircraft parts (pitot probe for example). <S> In this case the blades are dented, in which case it is possible to replace the damaged parts, inspect the engine and re-use it. <S> For this kind of damage it has to be disassembled and inspected by the engine manufacturer. <S> Inspection of blades is done with a microscope: For example, I have seen an HPT blade declared unserviceable because of a small scratch. <S> Obviously if the repair costs more than a new engine you don't repair the old one. <S> Many more things can happen in startup: The engine is run on full power <S> There is a lot of possible interactions (like birds for example) that you don't have in a steady cruise at 40,000 feet. <S> Aside from debris, you can also have a compressor stall like this . <A> Jet engines are fairly expensive, accounting for a large part of the cost of an airliner. <S> So there will be some incentive to repair the engine if possible. <S> If it happens at startup and mostly causes a bunch of smoke, like in the linked video, then the damage may be fairly limited and will probably be repaired. <S> If damage is suspected, a borescope inspection is generally done to check the inner parts of the engine for damage as well. <S> If a failure happens at full thrust , the engine is probably finished. <S> Aircraft and engines are designed for this failure, but a full blade failure will cause extensive damage. <S> Parts that get loose and enter the engine core will cause further damage through the engine. <S> Also, serious failures are generally investigated, especially if they are considered uncontained . <S> This will mean at least extensive downtime for the engine, and may or may not end up being repaired. <S> There are many malfunctions that can occur at startup . <S> The engine has been shut down for some period of time, during which: Parts cool down and contract Debris can enter the engine Things can leak or get damaged <S> Whatever has changed will be discovered when the engine is started. <S> Also, the problem in the video seemed to only appear after taxiing for some distance, so the engine could have ingested FOD at some point. <S> It's not clear whether the 10 minute hold is due to ATC or the pilots noticing abnormal engine parameters. <A> Depending on the jet engine type and on the cause and amount of damage, an engine repair or module replacement could be carried out on the wing. <S> If damage or further investigation is needed, or if the aircraft is needed quickly, the engine could be removed to the airline's engine shop and parts/module/modules replaced on site. <S> Further damage may dictate the engine goes back to the manufacturer's overhaul shop or an approved overhaul facility: The engine will be stripped and each part inspected for serviceability. <S> The cost of repair will be calculated. <S> If the repair cost is higher than a new engine cost, the insurance company may deem it "beyond economical repair" and the engine is scrapped. <S> If the repair cost is acceptable then the engine may be repaired or fully overhauled depending on the operating hours <S> /cycles already accrued in service: A low-hour damaged engine may just be repaired, whilst it would be more economical to fully overhaul a high-hour damaged engine to bring it back to "nil hours since last overhaul status".
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Whether an engine is repairable is dependent on the failure.
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What is the oldest aircraft still in production? What is the oldest aircraft still in production? I Googled it but only got the answer to the oldest military aircraft still in production. <Q> Longest production run (civil) <S> Even during the general aviation downturn in the US of the 1980s & 90s, production continued, as Kevin Cathcart pointed out in the comments: FAA registrations show no gap in years of manufacture of the A36 Bonaza. <S> I was able to find a registration for one manufactured in every year from 1980-1999 in california alone. <S> Production did drastically slow during that time frame, but it never stopped. <S> Longest production run (military) <S> The Lockheed C-130 Hercules military transport first flew in 1954 and has been in continuous production ever since. <S> According to Wikipedia, they've even been built in the same factory (in Marietta, Georgia) the entire time. <S> Because only around 2,300 have been produced (only!), they don't show up on the 'most produced aircraft list' mentioned in another answer. <A> I don't know if it counts, but the Messerschmitt Me-262 has seen a second production run of five aircraft being finished earlier this century after approx <S> . <S> 1500 had been built before the middle of the last, from 1941 - 1945. <S> The new production was started in 1993 by the Texas Aircraft Factory, led by someone who had learned metal aircraft craftsmanship as an apprentice in Germany during WW II and who later moved to the US. <S> The job was finished in Seattle by ex-Boeing people, and the aircraft were rivet-for-rivet copies from the original design, with one exception: They are powered by J-85 engines instead of the old Junkers 004B . <S> The Junkers jets were similar in size and mass to the EJ 200 of the Eurofighter, but with 1/7 of the thrust and just 50 hours between overhauls were considered a liability. <S> Already in 1950, in the early phase of the Korean war, a new series of the Me-262 was briefly considered when US aircraft found themselves to be outclassed by Soviet-built jets . <S> In the end, the Me-262 wing design heavily influenced that of the North American F-86 Sabre . <A> The Great Lakes 2T1A biplane trainer was designed during the roaring 20s and first flew in 1929. <S> While there were many gaps in production over the years as the company and plans changed hands, it is currently in production - a design close to 90 years old! <A> A gander on the list of most produced aircraft on Wikipedia suggests the Cessna 172 which started production in 1956 and is still produced today. <S> However the Aeronca Model 7 Champion has returned to production in 2007 after a short production run from 1945-1950.
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The Beechcraft Bonanza seems like a likely candidate for 'oldest design still being made'; first flight was 1945, and it's still in production today (albeit made by the same parent company that makes Cessnas!).
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Why aren't test planes remote controlled? There was a recent accident where SpaceShip2 broke apart in mid-flight, killing one and injuring another. Given that we can remotely control drones from the other side of the world, why couldn't we do the same with this test airplane? Considering that it's all launched locally, it would not even have the lag that drones have. <Q> They do it with old fighter jets for use as target drones. <S> But a target drone's task is pretty simple; fly like a fighter jet until it gets shot down. <S> At the point where SpaceShipTwo is, a bunch of testing has already been done. <S> This is supposed to show that the vehicle is safe enough to move on to piloted testing. <S> But testing aircraft and spacecraft is a dangerous job and things happen . <S> Creating a remote control system for an spacecraft like SpaceShipTwo would be much more of an issue. <S> First of all, there will most likely be physical changes required, whether this is to install hardware to manipulate controls, or just electronics to remotely operate the flight computers. <S> These physical changes will be extra work and will affect the tests, since when the plane is actually operating, those things won't be in place. <S> And if those remote control systems fail, you lose the aircraft. <S> Sure, you don't lose pilots, but why lose a plane just because a remote control system (which won't be used on production) fails? <S> Should you spend time and money developing a complicated remote control system, or developing the actual vehicle? <S> Also, many tests require the pilots to be on board. <S> They are not just testing the systems, but how the pilots interface with them. <S> Having real pilots actually flying the vehicle is the whole point of this phase of testing. <S> See this related question as well: <S> Why do the engineers need to be on board during testing? <A> Today's highly automated airplanes should be not too hard to control remotely - after all, all the cockpit control inputs become electrical signals, and at that point a multichannel remote could be plugged in. <S> The Russians even flew their Buran version of the Space Shuttle autonomously, using a neural network to command the craft on its single flight in 1988. <S> However, a test pilot flies an aircraft with all his senses. <S> Without the acceleration, a full 3D-view and the force feedback from the controls, he doesn't get the full picture when sitting in a control room and looking at screens full of data. <S> That is done by test engineers anyway, and the pilot's job is to complete the observation of a new airplane's behavior by exposing himself to it. <S> You might argue that the 3D-view is just a matter of several cameras and displays, but the needed telemetry bandwidth for this would be immense. <S> In a normal test flight, already hundreds of parameters are measured many times a second and transmitted to a ground station, where specialists for each system watch for anomalies in the data. <S> It is much better to spend the telemetry budget for this than to send pictures down. <S> The lack of acceleration and vibration alone would deprive the test pilot of an essential part of the picture, because it simply cannot be realistically recreated in a ground station. <S> Also, the inevitable delays incurred by radio transmission and processing for display will quickly put a pilot out of a loop which he could easily control if he were sitting in the airplane. <S> The range of controllable eigenfrequencies would be reduced to phenomena happening at maybe 0.2 Hertz or less, whereas a pilot in the cockpit can comfortably stay ahead of oscillations with 0.5 Hertz or less. <S> However, it must be said that sometimes the test pilot does turn out to be a burden for the progress of the flight. <S> On the second flight of the British TSR-2 prototype , one fuel pump began to develop an imbalance, oscillating just at the eigenfrequency of the pilot's eyeballs. <S> He had to throttle back one of the engines to regain his vision. <A> Remote control systems have bugs and problems the same as any other system. <S> If you install a remote control system, you now have two systems that need to be tested, checked, maintained and working properly. <S> If there's a problem, and the vehicle crashes, you're immediately left with two possibilities: maybe the aircraft had a problem, or maybe the remote control system had a problem. <S> If the remote control system had a problem, maybe your airplane was fine, and you just lost a perfectly good plane due to a bug in your test system! <A> Barnes Wallis asked this question in the 1940s. <S> The loss of life in the Dams Raid deeply affected him and he was adamant that he would not risk human life on his more experimental post-war designs until their basic concepts were proven through unmanned flight. <S> ( Source for this and details below) <S> These included the revolutionary Wild Goose and later Swallow designs, where variable geometry wings were used, not just to improve wing efficiency across a range of flight conditions (as in the much later F-111 and Tornado) but to eliminate the tail and its associated weight and drag penalties altogether. <S> Wild Goose flew (remotely controlled) in January 1950. <S> However testing seems to have been slow and remote control techniques of the time didn't help. <S> Without onboard cameras, at least one model was crashed by a pilot misjudging its position from a distance. <S> Swallow (in the form of a rocket propelled model) is reported to have flown stably at Mach 2.5 in 1955. <S> Neither progressed to manned prototypes, thanks in part to financial difficulties in post-war Britain. <S> In any case the intent was to prove the basic concepts rather than perform all testing in unmanned form, experimental manned planes were to be built along proven aerodynamic lines.
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Taking a plane that is designed to be operated by humans and retrofitting a system for remote control would be a big task.
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Does the pressure change inside a plane when it is opened for paratroopers? Does the pressure change inside a plane when it is opened for paratroopers? <Q> For low deployment the cabin pressure is already equal to the outside pressure. <S> For High altitude jumps the pressure is reduced to the outside pressure before opening the door (and everyone puts on oxygen masks). <A> It depends! <S> When people jump off an airplane with parachutes, there are two categories: Skydiving <S> This is normally done at lower altitudes, somewhere from 1,000 meters (3,000 ft <S> ) - 4,000 meters (13,000 ft). <S> The airplanes used typically for this purpose do not have a pressurized cabin. <S> So when the door opens for paratroopers to jump, pressure outside is almost the same as inside. <S> After the jump, the door is closed and everyone is happy. <S> This is a Cessna 208 configured for skydiving, with a door visible on the port side of the aircraft. <S> High-altitude military parachuting <S> These jumps are done from 4,600 meters (15000 ft) and 11,000 meters (35,000 ft). <S> At 35,000 ft, only 26% of the Oxygen is available when compared to the amount at sea level. <S> When the door is opened at such high altitudes, amount of available Oxygen is no longer sufficient for humans and everyone needs to wear the Oxygen mask to avoid sickness due to high altitude . <S> More about re-pressurization of cabins is discussed here . <S> As far as the paratroopers are concerned, they wear special gear, which looks like this: <A> It does. <S> The actual pressure difference will depend on various factors like door placement and size, aircraft slip, but mostly and especially on aircraft speed. <S> For a normal skydiving operating speed (say <100kts) this will raise the cabin altitude by no more than 100-200 feet.
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When you open the door, Bernoulli's principle guarantees the pressure in the cabin will drop (yes, lower than outside).
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Can you obtain a pilot license with impaired vision / being blind in one eye? A friend of mine is blind in one eye and has normal vision in the other eye. Would this prevent him from getting a Private Pilots License in the US? <Q> An applicant will be considered monocular when there is only one eye or when the best corrected distant visual acuity in the poorer eye is no better than 20/200. <S> An individual with one eye, or effective visual acuity equivalent to monocular, may be considered for medical certification, any class, through the special issuance section of part 67 (14 CFR 67.401). <A> It is both perfectly safe and perfectly legal to fly with monocular vision. <S> Safe: <S> A classic US Air Force study (that led to a revolution in the study of vision and neuroscience more broadly) demonstrated many decades ago that (a) <S> our sense of depth comes from many sources, and <S> (b) stereo is of remarkably limited utility in many situations -- for example, when objects are much further away than the distance between our eyes, as is the case in most situations while flying. <S> Motion is in many cases far more important. <S> This is extremely well established in the literature. <S> Legal: as mentioned in a previous answer, monocular pilots require a special waiver for their medical certification. <S> The reason is simple: monocular vision, by itself, is not a biggie; but if you have one eye, it's worth making sure there's nothing else amiss, and that a pilot with recent loss of vision has developed the intuition required to comfortably sense depth with other cues. <S> Tell your friend to go do it! <A> I was a victim of a virus in one eye that blinded me in that eye. <S> After a competency check ride with the FAA with vision in only one eye, I am back to flying like I always did. <S> Obviously, curiosity set in with me, so I asked around and was surprised to find that many pilots are blind in one eye, and like me, vision in only one eye has not affected their enthusiasm or enjoyment of flying. <S> I am a commercial pilot, and was informed by my medical examiner that there are many airline pilots who also are blind in one eye. <S> The point is that you can become a professional pilot if you have vision in only one eye. <A> Just an addition to the previous answer, While they may be legally able to get a medical cert and complete the training they may find it extremely difficult. <S> Having vision in only one eye can have a drastic impact on depth perception and ones ability to observe motion. <S> The human body can see distance, and motion (distance change over time) largely by triangulating objects from both eyes. <S> If the loss in vision happened later in life many people are able to retain enough estimation ability to still be able to see and estimate motion and distance with ease. <S> While I would advise him to give it a try he may find certain things very difficult <S> and he should be prepared for that. <S> I would also strongly advise an instrument rating in this case so as not to need to rely on vision all the time.
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I have never noticed an issue with flying with vision in only one eye. It's possible to get a special issuance medical certificate in this case :
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Why does Schiphol Airport have such a long taxi? I recently flew into Schiphol and experienced a very long taxi time (about 20 minutes) from landing to pulling into the pier at the terminal. Given that the flight was only 90 minutes from closing air plane doors to opening air plane doors. I feel that over 20% of flight time is a little excessive for taxiing at the destination airport. I landed in the early evening. Around 19:30 local time with KLM. Looking at a map I think I landed at Polderbaan runway as we crossed a main highway. Possibly the A5. My question is: Why does Schiphol build a runway so remote when there is clearly available land nearer to the main airport terminal? And should this runway be used by short haul flights. Should it not be kept for long haul as it is the widest and longest runway at Schiphol? <Q> Schiphol indeed seems to have enough space to build a runway close to the terminal. <S> However it is more the lack of airspace and laws preventing excessive sound levels that made it necessary to create the "polderbaan". <S> It is also one of the two primary runways for nightflights (link in Dutch (sorry). <S> Found a reference in the English wikipedia : <S> Newest runway, opened 2003. <S> Located to reduce the noise impact on the surrounding population; aircraft have a lengthy 15-minute taxi to and from the Terminal. <A> In addition to the noise issue mentioned in andra's answer, the Polderbaan (36L/18R,) Zwanenburgbaan (36C/18C,) and Aalsmeerbaan (36R/18L) runways are parallel. <S> For parallel runways to be used simultaneously (especially if they can all be used for simultaneous arrivals or all used for simultaneous departures,) then there must be a minimum amount of separation between them in order to maintain the required horizontal separation between the air traffic. <S> This may also be part of why the 36L/18R runway is so far away horizontally. <S> An additional factor in the taxi time is that traffic going to or from the 36L/18R runway must taxi around the 36C/18C runway if it is being actively used for an arrival or departure. <S> As far as runways being 'reserved,' most airports don't reserve particular runways for long-haul flights. <S> They may be given preference on a particular runway if it's needed, but that's unlikely to often be the case here, as all three of the parallel runways at Schiphol are sufficiently long for almost any passenger aircraft (they're all over 10,000 ft.) <S> [1] <S> In cases of parallel runways that are all sufficiently long, arrival runways are usually assigned more on a basis of which direction the traffic is arriving from than anything else. <A> Moving the runway further away gives Schiphol the chance to build an extra set of terminals which could connect to the main road. <S> Also, land in Holland is expensive and noise pollution rules are strict, so it was best to build anything new in the middle of a field (an aerial view will show this).
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Which part of the airport the traffic will be taxiing to and how long of a line there is for each runway also may factor into the decision.
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Why do lavatories in modern planes still have ash trays? Last week I flew on a modern B737-700 . I noticed that the lavatory was equipped with ashtrays (both on the inside as on the outside) even with the smoking sign on it. Smoking on airplanes has been banned from quite some time now, so why are lavatories still built where ash trays are provided? <Q> Because in the US (where Boeings are made) it's required by law. <S> 14 CFR 25.853(g) <S> says: (g) <S> Regardless of whether smoking is allowed in any other part of the airplane, lavatories must have self-contained, removable ashtrays located conspicuously on or near the entry side of each lavatory door, except that one ashtray may serve more than one lavatory door if the ashtray can be seen readily from the cabin side of each lavatory served. <S> The law may be different in other jurisdictions, of course. <S> Why the law still exists is another question, but either no one found the time to change it (laws are often very difficult to change once passed) or it was a deliberate decision to keep requiring ashtrays in case someone tries to smoke anyway. <S> EDIT: <S> As commenters have noted, the law I quoted requires ashtrays outside the lavatories <S> but it's still common to find them inside . <S> My guess here is that the ones outside comply with the letter of the law, whereas the ones inside comply with the intent , i.e. they're there because if someone does light up, it will be inside the lavatory and not outside in plain view. <S> This 2012 article quotes an anonymous FAA source as saying that people continue to smoke on aircraft so it still makes sense to have them for safety reasons. <S> That raises the question (again) of why the law doesn't fully reflect reality, but that's neither unusual nor unique to aviation. <A> It's for safety. <S> A possible cause of the fire was that the lavatory waste bin contents caught fire after a still lit cigarette was thrown into it, the FAA issued AD 74-08-09 requiring "installation of placards prohibiting smoking in the lavatory and disposal of cigarettes in the lavatory waste receptacles; establishment of a procedure to announce to airplane occupants that smoking is prohibited in the lavatories; installation of ashtrays at certain locations; and repetitive inspections to ensure that lavatory waste receptacle doors operate correctly". <S> Here is the latest revision of FAA Airworthiness Directive 74-08-09 . <A> "One size fits all". <S> Since smoking is/may be allowed on some foreign airlines, it would be silly for Boeing and other manufacturers to build airliners that were smoker-equipped and those for non-smoking. <S> It is easier and less costly to install ashtrays on all aircraft and just keep the no smoking light on for those flights where smoking is prohibited.
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Smoking may be prohibited, but if a passenger smokes anyway, you don't want the remains of the cigarette to start a fire due to improper disposal, as probably happened with Varig Flight 820 :
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What if pilot feels too tired before his flight? Today is a day when I feel terribly tired. I'm not ill, but I could sleep all the day, though I had enough sleep last night. This is not a problem if you have an office job where you can probably be not as productive than on other days. But what about pilots? They are expected to have a high level of concentration and vigilance during the whole flight? This question, What should a pilot do if they feel sleepy? concentrates more on upcoming sleepiness during the flight. The accepted answer says: If a pilot is not rested enough to safely operate the aircraft, they should not fly. [...] Well, "should not" sounds more like advice than a rule. You may say that there are always two pilots on (not so long) commercial flights, but then you can also start with one faulty engine, because the second engine still could bring you to your destination. For me, this breaks the safety concept. So, can a pilot go to a doctor and tell, "I'm tired today so I can't work"? <Q> So if you are well rested and not ill, but still feeling tired, there has to be something else wrong. <S> From your description, it appears to be fatigue . <S> The common signs for fatigue are: Falling asleep Yawning Poor visual acuity <S> Feeling "sluggish" or "drowsy" Decreased reaction time <S> Decreased concentration <S> Sleep disturbances Interruption of circadian rhythm <S> Mental or emotional stress Physical exertion, such as heavy exercise Poor health, including dehydration or poor diet <S> Pilots can assess their own fitness to fly by the IMSAFE mnemonic. <S> FAA has a small handout about fatigue. <S> Now what pilots (and generalizing, people) can do and actually do are two very different aspects. <S> A survey about European pilots mention: ... <S> many are afraid their fatigue reports could have negative consequences for their professional future (i.e. reprisals by management) ... <S> FAA has a new rule which states: <S> The FAA expects pilots and airlines to take joint responsibility when considering if a pilot is fit for duty, including fatigue resulting from pre-duty activities such as commuting. <S> At the beginning of each flight segment, a pilot is required to affirmatively state his or her fitness for duty. <S> If a pilot reports he or she is fatigued and unfit for duty, the airline must remove that pilot from duty immediately. <S> The answer to your question is: Yes, they can! <A> "So, does a pilot go to the doctor and say "I'm tired today, I can't work"?" <S> Simply put, "Yes. <S> Say you cannot work." . <S> If a surgeon cannot operate with full facilities, he doesn't operate. <S> The patient can have surgery tomorrow (in most cases). <S> If a pilot cannot be assured that he can perform, regardless of weather, mechanical issues, ATC delays, whatever, the passengers can be inconvenienced. <S> It is better than the alternative, which is ending up dead . <A> If you feel so tired and fatigued that you cannot safely operate an aircraft or perform your duties as a member of a multi-person flight crew, it is your call to do so, <S> but yes, you can call in to a supervisor and tell them you are simply unable to fly. <S> I don't know what the law is exactly <S> but it is probably illegal for an employer to discipline you or to terminate your employment for a single instance of this. <S> Multiple and/or frequent infractions could lead you into trouble with an employer as it is your responsibility to plan ahead and be well rested and nourished for a duty shift. <S> This issue garnered a lot of attention with the crash of Colgan Air (Continental) 3407 in Buffalo in 2009. <S> CVR tapes revealed a flight crew frequently yawning, and the FO complaining about long duty schedules as well as being ill and the cost of getting a hotel in order to get well. <S> It turned out that many commuter outfits were working pilots through 14-16 hour duty shifts plus commuting with very little concern for their well being aside from management demands that they "move the rig". <S> See the program Frontline: <S> Flying Cheap.
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Although, the most commonly known reason for fatigue is lack of sleep, but any or all of the following can cause fatigue: Lack of quality sleep
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Why did the Ju-87 Stuka have a siren? Why did the Ju-87 Stuka have a siren? Was this for purely psychological reasons or did it help the pilot in some way? <Q> Wikipedia : <S> The B-1 [variant] was also fitted with "Jericho trumpets", essentially propeller-driven sirens with a diameter of 0.7 m (2.3 ft) mounted on the wing's leading edge directly forward of the landing gear, or on the front edge of the fixed main gear fairing. <S> This was used to weaken enemy morale and enhance the intimidation of dive-bombing. <S> After the enemy became used to it, however, they were withdrawn. <S> The devices caused a loss of some 20–25 km/h (10-20 mph) through drag. <S> Instead, some bombs were fitted with whistles on the fin to produce the noise after release. <A> The psychology behind it helped the pilot ... <S> panicking enemies doesn't make for very good shots, they're more likely to miss you. <S> They're also more likely to just drop flat on the ground rather than dive into cover or try to shoot back at you. <S> And that was pretty much the idea. <S> Get the enemies to become disoriented, panicky, so they're less efficient fighters and easier to defeat by both you and the ground forces you're supporting. <A> Another reason for the siren is that during the first years of WWII most army's ground transportation was horse drawn. <S> You freak the horses and the unit does not move. <S> The French, Polish, and Russian armies used primarily horse drawn transport. <S> The British and American armies used trucks. <S> A truck can't freak out like a horse.
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So, yes, it was purely psychological and actually hindered the pilot by reducing air speed in ordinary flight and they were removed when they stopped having the psychological effect.
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How is lift provided by a wing affected by propeller wake? Does the lift of that section of the wing which is in the wake of the propeller increase (because the airspeed in that section is higher)? If yes, is this fact used actively to improve the lift capability? Or does it decrease significantly because of turbulence and an overall disturbed airflow on the wing surface? <Q> It both increases and decreases, depending on the local direction of the propellor (e.g. on the upgoing side, or the downgoing side) . <S> See for example this PhD thesis: <S> Propeller Wing Aerodynamic Interference . <S> This thesis shows the following image: Simply said, the velocity of the propellor locally changes the angle of attack, and thus the lift generated by the wing. <S> It is interesting to know that it is possible to locally optimize the shape of the wing to take advantage of this effect. <S> Again the thesis shows the result, and it looks like this: If you look closely, you can see that the wing is changed at the propellor location to accomodate the adjusted flow. <A> According to this NASA Document the lift after the propeller is higher and it is used on purpose to create more lift. <S> Page-5 Wing-mounted propulsion systems have significant effects on the wing aerodynamic characteristics, and these effects are more pronounced when the highlift components are deployed. <S> Various aerodynamic components contribute to the rise of these effects. <S> Some of these effects are external to the wing performance and affect the measurement of the aerodynamic characteristics of the combined assembly. <S> Examples of these effects are the propeller thrust, the location of the thrust line, tile size and location of the exhaust nozzle, and the thrust from the exhaust nozzle alone. <S> Another group of effects are pure aerodynamic effects, such as the propeller slipstream and the flow past the nacelle and nacelle attachments. <S> Page-7 <S> It is also stated, that the exhaust of the turboprop can also create lift. <S> For example:An exhaust of a free-turbine "PT6A-67" turboprop of a converted Conair Firecat doesn't generate any lift. <S> But an exhaust of an Direct-drive "Rolls-Royce RB.53 Dart" turboprop YS-11 which is nearly on the wing, can generate additional lift and acceleration. <A> There is a lot of work going on at NASA right now to take advantage of the additional lift created by propellers on the wing, which allows the wing to be thinner for the same amount of lift. <S> Look for a series of papers coming in June of 2015 on distributed electric propulsion where this is being exploited as a way to achieve additional efficiency.
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Results indicate that the lift coefficient of the powered wing could be increased by the propeller slipstream when the rotational speed (disk loading) was increased and high-lift devices were incorporated.
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What are the pros and cons of single-engine vs. twin-engine? Why would someone prefer to own a single-engine vs. a twin-engine airplane? What are the pros and cons of each? <Q> In the light aircraft world there are a few trade-offs to consider. <S> The short version: Single-Engine Pros: <S> Simplicity One engine means fewer controls, a simpler fuel system, simpler vacuum system, simpler electrical system, etc. <S> Operational cost Only one engine to feed <S> , so you spend less on - fuel & oil per flight. <S> Maintenance cost Only one engine to maintain - One set of spark plugs & cylinders, One engine to overhaul. <S> Single-Engine Cons: <S> No redundancy: You have one engine, if it fails you're a glider. <S> Singles generally tend to have less spacious cabins than twins. <S> Twin-Engine pros: Redundancy <S> If you lose an engine the other will give you a chance to get to a landing site. <S> Cabin space <S> If you step up beyond "twin trainers" you can get a very nice cabin in a piston twin. <S> Equipment Again, if you step up beyond the "twin trainers" twin-engine planes tend to be "traveling aircraft", so they often come with nice features like deice/anti-ice equipment. <S> Twin-Engine cons: Operating costs Two engines to feed (fuel & oil costs double). <S> Maintenance costs Two engines mean twice the cylinders, twice the spark plugs, etc. <S> Complexity <S> The redundancy you can get in a twin comes at a price: Synchronizing the propellers, a more complex fuel system (crossfeed), paralleling alternators, vacuum system failover, etc. <S> Short and Soft field performance can be lacking. <S> Failure of an engine can be problematic . <S> In addition to the operational considerations there are some other practical items to consider: twin-engine aircraft require a multi-engine rating (which means more training time). <S> Twins will also generally be more expensive to purchase/rent (and may be more difficult to rent when away from home), and will likely cost more to insure (particularly for low-time pilots). <A> Insofar as the safety issue that's been mentioned in the previous answers, there's a historical perspective on the question. <S> Engines are far more reliable than they used to be, and turbine engines are typically more reliable than piston engines. <S> As I remember, most pilots coming out of WW2 (including my father), considered twins safer than singles, certainly for over-water operations, but with the caveat that the pilot of a twin losing an engine had best be proficient in handling that. <S> Engine technology changed. <S> For example, the Cessna AT-17/T-50/UC-78 Bobcat , with two radial engines, was a 5-place twin in use through and after the war. <S> Certainly an argument could have been made that it was safer than single-engine planes with radial engines in use just after the war. <S> I certainly felt that way, an opinion gotten from my father. <S> However, by the time the six-seat Cessna 210 came along with it's horizontally opposed engine and flying higher and faster than that old twin, my guess is that most pilots familiar with both aircraft would prefer the single. <S> I certainly did, especially since I saw two engine fires that happened when starting the T-50 radial engines. <S> Now bring on the turbine-powered singles. <S> My guess is that most pilots would prefer a single turbine-powered aircraft to a horizontally opposed twin. <S> Having spent a lot of time in twin-engined, horizontally opposed, Cessna 310s (including one engine failure), personally I would opt for a single turbine, especially if it was a PT6 or Garret TPE331. <A> There are single engine, long range, large cabin aircraft. <S> A Flying Magazine article takes the example of the PC-12 in discussing single engine benefits: <S> All of the size, range and payload capabilities of the PC-12 flow from the fundamental design choice of using only one engine. <S> Carrying the fuel to feed a second engine, plus the weight and drag of the engine itself, all cut into range and payload. <S> The second engine and its costs also mean the twin-engine turboprop that comes closest to the PC-12 in cabin size and full fuel range falls hundreds of miles short when the same payload is aboard, and costs at least a million dollars more to buy. <S> If the single engine is very reliable this may be considered a moot point, especially since: <S> Single engine aircraft are certified under CFR 14 Part 23 : it may not have the ability to climb and the operational redundancy after engine fail that Part 25 aircraft must have. <S> So having a twin engine Part 23 aircraft may make the owner feel good about redundancy, but the aircraft's certification rules never demanded this to be demonstrated. <S> An aircraft with a very reliable single engine therefore seems to be the best choice under Part 23.
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A twin engine has twice the chance of engine failure that the single engine has! The con of having just the single engine is of course the consequence of an engine fail .
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Is it possible to use reverse thrust while airborne? I play a flight-sim called X Plane. The other day while I was approaching an airport a little too fast and knew I couldn't slow down in time. I decided to use the reverse thrust while I was still in the air and this helped dramatically and I was able to land safely. But now I'm curious - Would using reverse thrust in a real-life Boeing 747 have the same effect, would it cause the plane to crash, or go out of control? <Q> Commercial jets are not designed to use reverse thrust in flight. <S> With engines mounted under the wing, the turbulence can affect the lift over that section of wing. <S> Tail mounted engines could interfere with the tail. <S> This, in addition to the huge increase in drag, is what causes loss of control, as in the incidents that RedGrittyBrick mentions. <S> Speed brakes are designed to provide the needed drag for emergency descents or otherwise slowing down faster. <S> If the pilots find themselves too high/fast for an approach, and deploying spoilers/gear/flaps won't fix it, then they should go around for another approach. <S> The loss of control is more of a risk when a thrust reverser deploys only on one engine. <S> Other risks are still there, since those thrust reversers are designed to deploy in landing conditions, not flight conditions. <S> Notable exceptions listed on Wikipedia include the Hawker Siddeley Trident , though it also mentions that the capability was not often used. <S> Military aircraft, such as the C-17, can be different. <S> They tend to make extremely steep descents more often (called a tactical descent/approach), so thrust reversers can be used in flight . <S> I did some testing with the stock 747-400 in X-Plane. <S> Deploying the thrust reverser only changes the force applied by the engine, but doesn't seem to affect the air flow. <S> So the loss of lift is not reflected by the model. <A> It may depend on the aircraft and situation but an unintended deployment on one engine lead to the in-flight break up of a 767 <S> At approximately 15 minutes into the flight and at approximately 25,000 feet altitude, one flight crew member commented that the reverser had deployed. <S> This comment was immediately followed by evidence of a rapid airplane attitude change and subsequent in-flight break up, leading to airplane wreckage falling into remote jungle terrain approximately 94 nautical miles from Bangkok. <A> Here's a demo <S> https://www.youtube.com/watch?v=PU3RecxHRtk <A> As Skip Miller Mentioned the DC-8 thrust reverse was designed for in-flight operation. <S> Skip Miller: <S> It was years ago, but I was on a DC-8 that had been re-engined with turbofans. <S> On this flight, they used reverse thrust in flight to lose altitude quickly. <S> The Captain came on the intercom first to warn the pax of an unusual noise and vibration before he did it, and then he used the reverse thrust. <S> Yes, it was noticible and a bit noisey in the cabin. <S> I am glad he gave the pax warning. <S> Concerning the pax may be a reason why this is generally not done, even if the plane is capable of this maneuver. <S> DC-8 Manual ,American International Airways, page 29 Descent rates of less than 4000 ft/min are sufficient for all normal Operations. <S> A descent rate of 1 000 ft/min is about maximum that Will allow a precise comfortable Level off. <S> This should be closely monitored when within 2 000 Feet of the ground. <S> Reverse thrust, if necessary, may be used in normal descent at speeds above 1 90K IAS. <S> When this is done it is limited to inboard engines only. <S> Lauda Air Flight 004 <S> (NG0049) overview: <S> Some thrust reversers were designed for limited use in flight ( <S> such as inboard engines on the McDonnell Douglas DC-8)
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The Pilatus PC-6 (a turboprop) can be put the prop into reverse pitch and descend nearly vertically.
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What exactly is a UK IMC rating? In chat , falstro mentioned the "UK IMC rating" and described it as "a lighter version of an instrument rating, allows enroute IFR, but no approaches or departures" (although to be fair he also said that he isn't familiar with the exact definition). The name "IMC rating" implies that it allows flight in IMC, not just filing IFR in VMC for procedural reasons. But if so, and if approaches are not included, then it seems like it would allow a pilot to fly into IMC with no safe way out again if an emergency required an instrument approach. So what exactly is a UK IMC rating, what does it not allow that a full instrument rating does, and what is the advantage of having it? <Q> This is also know in Europe as an Enroute Instrument Rating or EIR , which allows flights under Instrument Flight Rules in the cruise phase, but not for departure or approach. <S> It is based on EASA FCL 825 FCL.825 <S> En-route Instrument Rating (EIR) (a) Privileges and conditions. <S> (1) <S> The privileges of the holder of an en-route instrument rating (EIR) are to conduct flights by day under IFR or in IMC in the en-route phase of flight, with any aeroplane for which a class or type rating is held. <S> The curriculum to obtain an EIR is lower than for a full Instrument Rating (IR), especially the number of hours for theoretical and practical instructions have been lowered: (2) instrument flight instruction. <S> (i) <S> The instrument flight instruction for a single-engine EIR shall include at least 15 hours of flight time by reference to instruments. <S> As GdD has pointed out in his answer , this is not the same as the UK CAA IMC Rating. <S> See his answer for more information on this. <A> Falstro's referring to the european en-route IFR rating, not the UK IMC rating. <S> It can only be used within the UK, not including the channel islands, which means once you leave UK airspace you are no longer allowed to use it. <S> Training for it is a similar curriculum as any other instrument rating: <S> NDB and VOR tracking Partial panel <S> Unusual attitude recovery ILS, VOR, NDB, and Surveillance Radar approaches <S> The reason for the UK rating is to give private pilots an attainable instrument rating option as the EASA one is aimed at commercial pilots and has a huge amount of unnecessary material and training requirements. <S> This is supposedly being worked on but given it's the EU <S> I'm not holding my breath. <A> The advantage of having it is that is enables more pilots, due to the lower barriers to obtaining the rating, to fly IMC, for example "on top", if caught out by unexpected weather which has been a consistent killer of PPLs, particularly due to CFIT. <S> It also opens more opportunities when weather en-route would otherwise prevent a flight and, can provide a more comfortable flight with higher altitudes and guaranteed separation.
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The UK IMC rating (I have one) is a national rating which allows departures, approaches and flight in instrument meteorological conditions, albeit with higher minimums.
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