source
stringlengths 620
29.3k
| target
stringlengths 12
1.24k
|
|---|---|
Was I nearly involved in an accident? This is a while ago but it has been bugging me now and then. On September 11 2011 (yes exactly 10 years after 9/11!) I was flying Easyjet 3467 from London Stansted Airport (STN) to Copenhagen (CPH). Scheduled departure was 18:40 local time but the flight was heavily delayed (around 4 hours as I recall) due to another bizarre incident. Anyway, as we were finally sitting in the plane and taxiing, suddenly the pilot announces that he just got info that another airplane had been heading to land just where we were and had only been some 60 seconds away! A lot of passengers seemed to gasp for air and the pilot sounded quite shocked as well. But there was no other explanation added. Is there a database of such events so I could look up more about what happened? I found the flight on FlightStats (sign in required) but there were no real info. <Q> No, you were not nearly involved in an accident. <S> If the flight crew is ready to go, an Airbus A320 takes about 40-50 seconds from the moment take-off clearance is given until lift-off. <S> As soon as the aircraft is off the runway, the next one can land. <S> On some busy airports, 60 seconds between take-off clearance and the next landing is a daily occurrence. <S> In 60 seconds, there is a lot that can prevent an accident. <S> For example, ATC could instruct the incoming aircraft to go around should the departing traffic not be ready to take-off. <S> This is quite a normal event which happens every day at busy airports around the world. <S> In such a case, the aircraft ready for take-off would have to wait for the incoming traffic to pass overhead. <S> It sounds like you may have experienced such an event. <S> Here is a video of something similar happening in Birmingham. <S> Since it is a 'normal' event, there is no central database that tracks these issues. <A> To figure out whether or not a situation qualifies as an “aircraft accident” we must look to the definitions in Part 830. <S> The NTSB defines an “aircraft accident” to mean “an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage .” <S> The first portion of this definition is especially important to note for maintenance and ramp personnel. <S> The initial threshold for classification as an aircraft accident is that the aircraft is being operated “with the intention of flight.” <S> Since no injury or damage occurred, the even would be classified as an "incident". <S> In the US, NASA runs the Aviation Safety Reporting System , a publicly searchable database of accidents and incidents. <S> The data are mostly about events in the US, although some international incidents are included as well. <S> The incident you mentioned doesn't appear. <S> The European equivalent appears to be ECCAIRS . <S> Unfortunately, access to that database is "restricted to authorized authorities." <A> There was probably no incident. <S> It just means your plane was ready to take off and had to wait longer than expected. <S> Whenever a plane is ready to go the controller has to decide whether he can let it go or should wait for an incoming plane. <S> The controller was probably just playing it safe and decided to make your plane wait, so the pilot got a little exasperated, "Sorry folks, got to wait for another plane to land."
|
The term you want to look for is not "accident", but "incident" .
|
How do pilots foresee turbulence? During a normal flight at cruise speed and altitude, amid the delicious airline meal and the enjoying a latest movie, all of a sudden the seat belt sign turns on. Then a few seconds later we enter turbulence, grab a hold of that half-finished soda cup and wait patiently for the bumps to be over while looking out the window. So, how exactly do the pilots know that the airplane is about to enter in an air pocket which will cause turbulence? ... or does it happen like this ? I have already gone through the excellent answers here and here . <Q> There are a few ways that pilots are aware of potentially turbulent areas. <S> Eyesight <S> The most obvious way is just by looking outside and observing the sky. <S> Large billowing clouds, called cumulus clouds, indicated pockets of unstable air (the clouds are rising because the air under them is as well). <S> If the pilots must fly through these clouds then its a safe bet that there will be some turbulence. <S> Weather Radar Just like using your eyes, except the radar can see further through haze and other clouds. <S> Typically this is useful for finding embedded thunderstorms, but it can also be useful to find areas of potential turbulence. <S> Communication Pilots talk. <S> Both to each other and to air traffic controllers. <S> En route controllers frequently ask pilots for "PIREPS" (pilot reports), to build an accurate picture of the flight conditions at different altitudes. <S> Often commercial aircraft will request to change altitudes or deviate around weather/ turbulence, so it is in the best interest of the controller to know ahead of time where the bad flight conditions are, and have a game plan of how to route traffic. <S> This makes it much easier for the controller to route traffic, rather than getting request after request from individual aircraft. <A> TL;DR clouds and a Doppler radar in the nose registering uneven air. <S> If the plane flies into clouds then there will get some turbulence because at the boundary the air will change, especially in thunderclouds. <S> Clear air turbulence is more devious as it happen in clear air (like it says in the name), these are detected by instruments on the plane like a Doppler radar that can detect the uneven air ahead. <A> At night time and with a broken radar.... <S> The above mentioned methods are good but the ability to plan ahead and perhaps even give you that brief whilst we are on the ground is due to the fact that we always carry the latest Significant Weather (SIGWX) charts that cover our route. <S> Here's what one looks like ( view in new tab ): <S> You can find a legend for such a chart online <S> but basically the thick bold lines indicate strong upper level winds (also known as jet streams). <S> Crossing one of these at right angles is what brings the most amount of turbulence. <S> Second to that, the areas contained within the cloudy bubble like shapes (making it very easy for you to understand here ;) ) are areas in which we can expect to find CB clouds or other storm related activity. <S> Of course, flying through a big lumpy CB cloud will almost always have turbulence associated with it. <S> ISOL EMBD means the CB clouds are isolated (relatively speaking few and far in between) and may also be embedded inside other types of clouds that are in that area. <S> Most of the time and especially in winter we fly above these areas anyway (for cruise at least). <A> Pireps is how I get most of my info. <S> And you should pass them along on handoffs between controllers. <S> When I get a handoff <S> I say something like "Denver Center, N12345, level 250, light chop". <S> They will respond back with "N12345, Denver Center, it should smooth out in 50 miles or so". <A> According to the FAA the official Way is still ask a Flight Service Specialists in preflight briefing who the weather forecasts are and if turbulence can occur. <S> But additional in the preflight briefing the Pilots can see like on this Site the turbulences. <S> It is also stated in this FAA Document: <S> For pilot reports (PIREPs), the ADDS Java tool can zoom in on a specific part of the country and specify the type of hazard reported (icing, turbulence, sky and weather). <S> The tool also allows you to limit data to specified altitudes and time periods. <S> Map overlays including counties, highways, VORs, and Air Route Traffic Control Boundaries are available. <A> The most common means in level flight is actually the least technological: pilots ahead of them report the turbulence in that area. <S> If you are listening to the pilot chatter, and you hear "there is light chop", you can guess that the seatbelt light is about to come on. <S> (This is an interesting answer to a related question illustrating this point - the pilot refers to "ride reports" and PIREPS .) <S> Generally, if weather conditions are bad enough to show up on radar, you don't fly into them at all. <S> It's true that flying into clouds is another time when they know there will be turbulence, but this is most often on ascent or descent, and seatbelts will be on anyhow.
|
Besides those methods, planes ahead of them will be able to report that they experiences turbulence so the pilots behind them can anticipate.
|
What is a running rabbit? My father used to work as an air traffic controller, and often I heard mention of a 'running rabbit'. Obviously, vermin on the runways of airports can be a bad thing, but I don't think he was literally talking about animals. <Q> Background <S> The Sequenced Flashing Lights are part of some approach lighting systems and are a row of strobe lights that flash in sequence to direct the pilots eyes to the runway. <S> They are useful in conditions of bad weather, as they quickly catch the eye and help the pilot locate the runway threshold which might otherwise be hidden; however, during normal operations they can actually be distracting. <S> These lights appear to run towards the runway and are often called chasers, the rabbit, or the running rabbit. <S> Kill the Wabbit <S> Because these lights are very bright, and often distracting during normal operations in clear weather, it is not uncommon to hear pilots ask the controllers to kill the w/rabbit on their approach. <S> I personally find them overkill, and have heard many other pilots asked them to be turned off as well. <S> Photo credit ATG Airports <A> Check out this YouTube video . <S> Between approximate 0:18 and 0:30 <S> , you can see a set of strobe lights leading up to the runway. <S> They flash in sequence to make a moving dot that runs up the runway. <S> That is the "rabbit". <A> "Running Rabbit" is a colloquialism. <S> It refers to the sequenced flashing lights that lead up to the runway threshold, which are part of the ALS (Approach Lighting System). <S> From the wikipedia article linked above: Sequenced flashing lights are sometimes colloquially called the rabbit or the running rabbit. <A>
|
Running rabbits can also be a reference to primary targets appearing on a radar scope in a sweeping arc, often caused by radar interference from another radar or other spurious RF.
|
How much oxygen do commercial airliners carry? How much oxygen do commercial airliners carry? Is is enough for every seat to have a 20-30 minute supply, is it a percentage of total flight time (ie 10% of total flight time), or is there a compressor on board? I would assume the goal of the pilots during depressurization would be to repressurize whether that be by simply lowering altitude or other means. Thus, I would assume (hope) there would be sufficient reserves of O2 to do one or the other. <Q> The masks are connected to a chemical oxygen generator by a lanyard. <S> Pulling the mask pulls the lanyard, which pulls a pin from the generator and starts the reaction. <S> They typically last betweeen about 10 and 20 minutes, more than enough time to get down to 10,000 feet where additional oxygen is not required. <S> There is no need for a % of flight time since the crew will descend to a safe altitude then divert to the nearest suitable field. <S> Therefore, the only requirement is to last during the (emergency) descent. <S> You cannot "repressurise" since the cabin altitude will be the same as the external altitude. <S> The only thing to do is to increase the partial pressure of oxygen by descending. <S> It's worth mentioning that the flight crew each have their own, isolated supply from a bottle which lasts significantly longer. <S> This is so that they can continue to fly if there are fumes in the cockpit. <S> Cabin crew often have their own, smaller, portable bottles so that they can freely move about the cabin to assist the "self loading freight". <S> Many's a morning when I would arrive to work feeling, ahem, a little "under the weather" and nip into the cockpit for a couple of minutes on 100% oxygen. <S> Works wonders - and don't worry, they are topped up to full as part of the pre-flight service. <A> They don't carry oxygen tanks for each passenger but instead use chemical oxygen generators that activate can provide at least 15 minutes of oxygen. <S> They activate when the person pulls down the mask. <S> These 15 minutes is enough for an emergency descent to a safe altitude ~10k <S> ft where there's enough oxygen in the air for people to breathe without needing the mask any more. <A> While some pressurized aircraft use oxygen generators as others have described, others use pressurized (up to 3000 psi) gaseous oxygen canisters. <S> An engineer who designs such systems showed me how central oxygen systems work, but I believe there are smaller units (per seat group) on B787s and A350 XWBs.
|
They would carry at least 15 minutes of oxygen, but how long it lasts depends on how many people are using masks.
|
What is the cable connected to a plane for? I've seen that airplanes are connected to some wire like in the picture. What is it's name and what is it for? <Q> This is important especially during boarding, when the cabin lighting needs to remain on for passengers to embark or disembark. <S> The GPU is also used to start the APU, which in turn provides electricity to start the engines and the generators. <S> A ground power unit (GPU) is a vehicle capable of supplying power to aircraft parked on the ground. <S> Ground power units may also be built into the jetway, making it even easier to supply electrical power to aircraft. <S> Many aircraft require 28 V of direct current and 115 V 400 Hz of alternating current. <S> The electric energy is carried from a generator to a connection on the aircraft via 3 phase 4-wire insulated cable capable of handling 261 amps (90 kVA). <S> These connectors are standard for all aircraft, as defined in ISO 6858. <S> Source: Wikipedia <S> Related Questions: <S> Can large airliners be operated without ground support? <S> How are turbine engines started? <A> It provides power to the plane for when the engines and APU are not running while sitting at the gate to save fuel. <S> It allows the cabin lights to remain on so the passengers aren't tripping over each other as they board. <S> The power may also be used to start the APU that will in turn provide the power needed to start the main engines. <A> There are two kinds of GPUs: <S> The ones that are fixed and supply power to the aircraft The ones which are mobile, which are tugged to the stationary aircraft <S> The cables are connected by groundcrew before the pilot shuts down all engines. <S> It is different from pilot to pilot. <S> The APU remains on while the aircraft is being serviced. <A> It is ground power unit. <S> Due to the technical difficulty on ground to operate APU, which is the source of power for the aircraft. <S> Aircraft engineers connect GPU.
|
This is a ground power unit (GPU) which supplies the aircraft with electricity while the generators or the auxiliary power unit (APU) are not running.
|
Where to find a waypoints/fixed points, navaids and airports database? I wonder if it is possible to download a database with waypoints, navaids, airports and airways between them. I've been working with AIP documents but it's difficult to get raw information from them and they only have information about waypoints. I happened to find skyvector.com and I thought there would be an easier way to obtain that amount of information. <Q> Nice question. <S> There are several ways how to get these information. <S> http://www.fallingrain.com/ : <S> free to use, no registration needed. <S> World database of the airports and waypoints. <S> From these information you could easily make DB for waypoints. <S> EUROCONTROL EAD ( https://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html ): free to use, registration needed. <S> Big advantage - real and up to date information for all ECTL countries. <S> But a bit difficult navigation. <S> JeppView ( http://ww1.jeppesen.com/ ): very expensive SW, but the best in this time. <S> You will find there all information which pilot needs. <S> But it is not real database. <S> Garmin for pilots ( http://www.garmin.com/en-US/explore/intheair/ ): <S> another not free SW, very similair to JeppView but lightweighted. <S> NAVIGRAPH ( http://www.navigraph.com ): <S> Great DB of all things which you need in FMC. <S> But I guess that they have it just for flight simulator. <S> You could downlod all data in one file :-) <A> I use the National Flight Data Center at http://nfdc.faa.gov <S> I had to write them a letter explaining why I wanted the data ( http://fplan.sf.net ) and they provided me with a login. <S> Now, every 56 days, they send me an email telling me there's an update available. <S> Bad news <S> : they recently switched from a flat file to some unbelievably convoluted xml format that I haven't yet written a parser for. <S> Also, it comes with a disclaimer that the data is not approved for navigation. <S> Given that I've already found two minor errors in it, just in the SF Bay area, that's understandable. <S> Edit: I forgot to mention that I keep a subset of the data on-line at SourceForge. <S> I try to keep it up to date. <S> It's at the Fplan project . <S> These files are in the old "nav" format; documentation is included in the zip file. <S> If someone needs these files, they're freely available and I'm happy to make small additions to the data if anybody wants, since I already have the tools to parse the FAA data files. <S> I'm also happy to share the tools if anybody wants. <A> Another good one for airports and navaids: http://opennav.com/ - has VORs, waypoints, etc. <A> I have successfully used The GPX Aviation Waypoint Generator from the free Navaid database ( http://navaid.com/GPX/ ) that outputs a GPX (XML type) file with all the waypoints, airports and every other elements you choose to include. <S> To make a request on this API, make sure you specify the min and max GPS coordinates of the area you want to cover. <S> This is a world wide database, not only for the US. <A> This is my first post so bare with me. <S> I don't know if you are trying to get one region only or a global data set. <S> The issue is that member states are responsible for their own airspace and thus airport/NAVAID/intersection/waypoint/so-on-and-so-forth location data. <S> You may want to see about getting a copy of ICAO document 7910 <S> "Manual of ICAO identifiers" <S> This book cost money though. <S> If you are interested in the North American region (U.S./Mexico/Canada/Caribbean/and-so-on) then you can get for free the FAA Location Identifier book with FAA Order JO 7350.9x. <S> The lat/long of every waypoint/NAVAID/Airport and the like is in it. <S> Unlike a previous answer post you don't have to ask for access permission either. <S> To keep things simple here is a link. <S> FAA Location Identifiers <S> That's what I got for you <A> Updating: The link is at https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/NASR_Subscription/ <S> This provide the text file along with layout data for all the fixes, etc. <S> The CIFP can be downloaded as well, but the layout is commercialized (~$400). <S> I have not been able to programmatically download the zip file.
|
OpenFlights ( http://openflights.org/data.html ): free DB of airports, airlines and routes.
|
Where can I find data tables for lift and drag coefficients of airliners? I'm teaching an introductory course in fluid dynamics and I'd like to show some "real" data regarding drag and lift forces on an airfoil. It is easy to find data on the geometry of typical airfoils, but I was not so lucky with $C_L = f(airfoil, Re, i)$ and $C_D = f(airfoil, Re, i)$ ($Re$ is the Reynolds number and $i$ the angle of attack). I'm looking for that kind of diagram or data : Data for commonly known aircraft would be great (B737, B747, A320, A380). Thanks. <Q> My first thought was: Abbott-Doenhoff. <S> They wrote a book with lots of measurement data, and you can find it here . <S> Of course, this was all long ago, but public data for the airfoils of today's airliners are not published. <S> A lot of data is also freely available in old NACA and NASA reports, however, you need to know what data you want to search for it efficiently. <S> If you want to focus on glider airfoils, the Stuttgarter Profilekatalog would be my next source, but unfortunately there are still people who want to make money from it even though the work was financed with public money. <S> This is also quite old, and more modern airfoils from Delft University are similarly restricted. <S> Another great source is the UIUC airfoil database , but here the focus is on section data and not on polars. <S> But it contains many useful links with airfoil data. <S> And then there is always XFOIL : <S> Feed it with the coordinates, and you get very good simulations of what a wind tunnel would measure, at least as long as most of the flow is still attached. <S> Lots of plotting functions will help to uncover what is going on in much more detail than any wind tunnel data could ever hope to do. <A> I found a web site (mostly in French, but data are language agnostic!). <S> Calculation were made with XFOIL . <S> This is typically what can be found there (with data text file). <A> I think if you try with this site may be you can find a data that you need . http://airfoiltools.com/airfoil/details?airfoil=n0012-il <A> Another source: Modelled from independent analysis and maybe not necessarily provable, <S> but there’s some detailed estimates on 787 characteristics published here . <A> While a bit dated with respect to modern transport aircraft, Fluid Dynamic Drag and Fluid Dynamic Lift by S. Hoerner has a ton of data on just about every aspect of interest.
|
It’s a text book and as such not quite freely available, but Obert‘s Aerodynamic Design of Transport Aircraft has a lot of surprisingly accurate data (including e.g. 777 drag polars).
|
Why is a clock necessary for IFR? According to FAR 91.205 (d)(6) , one instrument required for IFR is: A clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation. Why is it necessary to time things in the cockpit, or know the time? <Q> An IFR clearance may have a void or release time <S> so that clearance is only valid between certain times. <S> For holding pattern legs. <S> A standard holding pattern is based on a time of one minute at or below 14,000' MSL and 1.5 minutes above 14,000' MSL on the inbound leg. <S> For holding pattern clearances. <S> Holding instructions include an EFC (expect further clearance) time , so that if you have a communication failure while holding then you know when you can safely leave the hold and start an approach. <S> For timed approaches , where an aircraft is cleared to start an approach at a specific time For timed turns. <S> A standard rate turn is 360 degrees in 2 minutes, so with only a timer and a turn coordinator you can turn a specific number of degrees. <S> For en route reporting and general time/distance calculations. <S> Especially in a non-radar environment (i.e. when ATC can't see you on radar) <S> you may be required to give ATC actual or estimated times for passing certain fixes. <S> (This is not strictly IFR only, but it's still relevant.) <S> All of these scenarios are discussed in detail in the FAA's Instrument Flying Handbook and in the AIM . <A> In IFR the pilot needs to have a second-accurate time indicator for a variety of maneuvers. <S> For example, the standard holding pattern is 1 minute turns and 1 minute straight legs. <A> When flying under IFR in IMC you have no external visual references, so there are a number of reasons you may need to time something: <S> Some approaches require you to be able to time them. <S> VOR approaches <S> have a table of times from the final approach fix to the missed approach point at a given groundspeed: Since you have no other way to judge distance over the ground you must use the clock. <S> A "normal" holding pattern consists of one-minute legs with one minute (180-degree) turns at each end. <S> Turns under IFR are assumed to be made at "standard rate" (3 degrees per second). <S> If your DG fails you can make "timed turns" with the turn coordinator, a compass, and a clock (30 seconds for a 90-degree turn, one minute for a 180, 2 minutes for a 360) and come out pretty close to your intended course, without being thrown off by compass lead/lag or acceleration errors. <S> There may be others but these are the ones that spring immediately to mind. <A> Some procedures require timing, e.g. holding over a fix or NAVAID is usually done in 1min legs. <S> Precise timing is necessary here. <S> Some clearances can also contain a time (e.g. release valid until, revised approach time, etc), where correct timing is necessary.
|
Having the number of seconds allows the pilot to fly these maneuvers accurately. There are several reasons: For departure clearances.
|
How fast can an F-22 scramble? The startup process in many military aircraft is, complicated, to say the least. It takes a lot longer than most would think. An F-16 from cold is required to be able to scramble within 5 minutes if on alert (armed, fueled, and pilot ready), 15 minutes if not. I also know that during the Cold War when the situation was expected to deteriorate, they could deploy B-52's to all runways (civilian airports included) that were longer than 9,000 feet, just sitting there with engines running ready to go. (Terrifying to think about...) I also found this: Default NATO QRA alert time is 15 minutes (in DEFCON 5), although the local CRC can lower that to ten (DEFCON 4), five (DEFCON 3) or even two minutes (DEFCON 2) depending on current state of affairs. At 5 minutes (DEFCON 3), the engines would be running idle 24/7, at 2 minutes (DEFCON 2) there are pilots in the cockpit 24/7. Anyways, an F-16 can scramble in 5 minutes. But an F-22 has an automated start process. IIRC, the checklist is something like... Master Switch On. Throttles Forward to idle. I understand that this may be classified, but I was wondering if anyone can put me in the ballpark. <Q> For military aircraft on "alert", there is a position called cocked on (or as some news sites call it, " hot-cocked "). <S> This procedure is run before the aircraft is placed on alert, and does a pre-flight check of all the instruments and then places them in a state that allows power application in a rapid manner. <S> This way, only minimal steps are required for the aircraft to be ready. <S> In addition to cocking on the aircraft, they can be parked in special areas (some are called Christmas Trees because of their appearance). <S> This allows the aircraft to reach the runway quickly. <S> Also, in the old SIOP days, there was an Alert Facility near where the aircraft were parked, where the crew would stay in a state of readiness. <S> Currently the full SIOP mission isn't active (it was ended in 1992 by President Bush, but there are still forces dedicated to it in a new capacity). <S> However, the facilities still exist on many bases. <S> They can use these facilities still for whatever alerts are required. <S> With an aircraft in cocked on position, with a pilot on alert (cockpit or facility), an aircraft can take off in a very, very short time (from seconds to minutes). <S> In general, the mission requirements will dictate the amount of time that the pilot is given to take off (as you note in your question). <S> So sadly, I can't give a specific answer to your question, because it depends on parameters you haven't specified. <A> You can start an f-22 in about 2 minutes or less. <S> The procedure is Master Batt. <S> APU(Auxiliary Power Unit) <S> Flip 2 generator switches flip nav and position lights as required for mission Make sure fuel switches are set right <S> Wait <S> a couple seconds for APU to finish start up push throttles to idle configure MFDs as needed as engines spin up. <S> taxi to runway <A> On a large airfield it could take more than 5 minutes just to taxi to the runway. <S> That means: <S> The pilot is fully ready and has all his stuff ready to go; literally waiting to jump into the plane <S> The aircraft has been pre-flighted, fueled and is on the apron ready to go Munitions have been loaded and checked Needless to say, keeping aircraft in this condition is expensive and I would imagine is only done at certain specific airbases where some special need for a fast launch is required. <S> Loading and unloading weapons is a very time-consuming process and there is a lot of red tape associated with it. <S> The time constraints have nothing to do with the type of aircraft. <S> It's more a question of the human factor and lots of little things. <S> Also, another factor is how much you are willing to skip. <S> You might have a 40-point checklist and 25 of them are "optional" items that pertain to safety. <S> If you don't care about dying, feel free to ignore them and you can take off 5 minutes faster. <A> As some other answers have mentioned, and some haven't, it varies very widely by readiness - whether the aircraft was expected to need to scramble. <S> The usual time for an aircraft to scramble in modern wartime would be 15 to 25 minutes. <S> This is from normally maintained readiness, for a typical post-cold-war conflict. <S> This figure came from a flight line ops Lt. <S> Col (not a pilot, the guy responsible for getting planes ready to fly), unofficial, but it aligns well with other information. <S> Newer aircraft are not much faster to start, since the steps are the same, and pilots know them; automation just simplifies it. <S> There's still more to it than just one switch. <S> The Chegg answer (hardly a place for such info) that seems to have been quoted in the question is not correct. <S> Engine ground running can be appropriate when an attack or a major war is expected. <S> Running aircraft can't be refueled, the pilot can't leave the cockpit, and parts run up the hours, so very few planes can be kept in such a condition. <S> Given how few F-22 exist at all, the US could realistically maintain 2-4 flights at such a readiness level.
|
If you maintain a plane on alert (expensive and time consuming), you could get it rolling inside of 5 minutes. There is no set time because there are too many factors.
|
Why don't airplanes have smoking cabins? Is there any airplane model that has a small lavatory-like cabin just for smoking? I have never seen any such planes and that made me wonder why this is? It would not take much more room than a normal lavatory, make it much less likely that someone will smoke in the lavatory regardless of the ban and provide smokers a way to satisfy their need. I will have to add that I am not a smoker, just a person with weird ideas/questions. Related Questions: • Are there any airlines that still allow smoking on-board flights • Was smoking banned because of passenger safety or occupational safety? <Q> Just off the top of my head, It would take up space that could be used for three or four <S> paying passengers. <S> This would result in increased ticket prices for everybody and the non-smoking majority have no incentive to subsidise a smoking cubicle. <S> It would require a ventilation system that would prevent smoky air from getting into the rest of the cabin, which would add weight and complexity. <S> (I guess an infra-red detector would work.) <S> isn't worth much. <S> Rates of smoking are decreasing in most Western countries, so demand for such a cubicle is already falling. <S> Anti-smoking legislation is often aimed at worker protection: who's going to clean the smoking cubicle and what equipment will they need? <S> I doubt there's significant pressure, even from smokers, for such a service to be provided. <A> It's against FAA regulations. <S> Wikipedia says so : <S> The Wikipedia article doesn't reference the FAA regulation and I haven't found it using Google <S> (I only found a document relating to smoking in FAA-controlled buildings ). <S> This 2010 Bloomberg article references nearly 700 law cases brought "by the FAA" (which might corroborate the claim in the Wikipedia article): <S> The Federal Aviation Administration has brought 696 cases, some for civil fines of thousands of dollars, against people caught smoking aboard airliners in the last five years, said Diane Spitaliere, an agency spokeswoman. <S> Lighting a cigarette on a plane has been banned for 20 years. <A> During 60's to 70's smoking was not prohibited. <S> However, every rule and prohibition depends on safety, prohibition of smoking on aircrafts also commits to safety of flight. <S> Smoking is a big crime on planes, if there are couple of attempts to smoke on a flight that`s considered as terrorist act, at that point whoever tries to smoke are accused as terrorist. <S> Pilots land aircraft to closest airport and police takes suspects from aircraft. <S> Possibility of fire is main reason for this rule. <S> Seats or floor could catch fire from cigarettes. <S> Even if you smoke lavatory, it is a lot more dangerous because there are lots of paper towels and etc. <S> that catches fire in lavatories. <S> Even if some special cabins has been built, there are still risk of fire because of inattention or terrorist could try to burn down the aircraft. <S> You could say that if somebody tries to burn down an airplane they could use lavatory to that. <S> Because of this aircraft lavatories are equipped with smoke detectors. <S> Essential of aviation rules to ban everything that could not be controlled up in the air.
|
It's a fire risk and a small fire from some idiot disposing of paper in the ashtray could spread; it would be hard to detect such a fire early because you couldn't just put a smoke detector in the smoking cubicle. According to FAA regulations, smoking lit cigarettes or anything else that produces smoke or flame is prohibited onboard most commercial aircraft. Almost nobody tries to smoke in the lavatory so reducing the occurrence of an event that hardly ever happens
|
Do lights on aircraft flash in a specific pattern? On a clear night, everyone can spot planes quite easily: they have flashing lights. I have noticed that the pattern seems different for different planes, and tried to find a meaning. What I saw so far is that they seem to have three lights that flash, two at the wings, one at the tail. Those at the wings flash two times (approximately per second, in quick succession), and that one at the tail flashes only once, along with the first flash of the wing. Now that explains two patterns I seem to see from further away: Two flashes and one flash. It is probably that I am just not seeing the wings flashing for those where I only see one. So far so good, but then again sometimes I see planes with more flashing, and those are faster. I had difficulties to count them, but it's at least three, maybe four quick flashes. Do these different patterns have any meaning? I tried to match up the planes with the flight radar information, but since it is quite crowded around here, I wasn't really able to identify them. But whenever I saw that quick flashing ones, there was a military plane around, is that just coincidence? <Q> Civilian aircraft have flashing lights based on manufacturer design preference. <S> As others have stated, aircraft like Boeing and Airbus have different patterns. <S> However, military aircraft can often select the pattern they want to use. <S> This helps military pilots identify key tactical aircraft during night operations, such as the tanker flying around the carrier. <S> It is definitely not coincidental that you noticed military aircraft with a unique pattern, although I'm truly shocked at your attention to detail. <A> No, the pattern has no meaning, though the double-flash does identify the plane as an Airbus; other manufacturers use a single flash. <A> Red flashing lights top and bottom of the aircraft are turned on when pilots are clear to start engine. <S> If you see those lights you know that there is an aircraft with running engines. <S> So it could be moving towards to you, so be careful. <S> Tail light is for it to be seen from behind. <S> The aircraft behind of you knows there is an aircraft in front of him. <S> Flashing light at wings means that this aircraft is airborned or about to be. <S> Pilots turns that lights on when they are on the runway. <S> These lights are stays put during the entire flight until the aircraft off the runway after landing. <A> In general, lights flash for the same reason that hazard lights on a car flash; because flashing lights are easier to see than solid lights. <S> This applies to a lot of things in aviation. <S> Building lights, tower lights, aircraft lights all flash because it is easier to see a strobe in low visibility than a steady light. <S> White strobes are also brighter and red strobes are less reactive to the eye (which is why cockpits use red light). <S> All of these combined help to make strobes easier to see and identify. <S> As to the pattern, as many have mentioned there is no specification on a specific pattern that aircraft manufacturers need to follow. <S> If I could take a guess, it would be so you can identify the orientation of the aircraft if you cannot still see the solid colored lights. <A> There's no specification for a pattern of flashing, and significant variations exist among different airlines and military. <S> There is a uniform requirement for position lights (steady red and green on the left and right wingtips, white on the tail) and an anti-collision light system which is one or more flashing lights which can be anywhere on the aircraft. <S> US requirements are in 14 CFR 25.1401, and say that the system must appear to flash between 40 and 100 times a minute. <S> Areas where lights overlap can have as many as 180 flashes per minute. <A> Example of anticolision lights pattern on military helicopter.. <S> Pilots can select the pattern they want to use according to tactical situation: <A> I don't know about civilian aircraft, but it's true that military aircraft have specific patterns. <S> Each aircraft role flashes differently. <S> Ill use F-18s as an example because they are multirole. <S> An F-18 tanker might flash <S> *, where an F-18 strike fighter might flash like <S> *- Both same aircraft but different jobs, hence different patterns
|
For an aircraft like an airbus, wing tips may have a different blink pattern because the manufacturer wanted it that way.
|
Why does the BAe 146 have higher maintenance costs than other comparable jet aircraft? In many discussion (1) (2) it is stated that the BAe 146 has higher maintenance cost and higher cost of operations in compare to other jets due to its complexity. Quoting IslandHopperCO (Reply 21): The PSA (then USAir) BAe-146s were parked in the desert in 1991 due to high maintenance costs according to USAir. More likely was that USAir couldn't turn a profit on the western routes that PSA used to make money on, because those routes were dropped when the plane were parked. No that is pretty much correct...PSA also had major problems with reliability. In fact BAE provided them with a spare because they broke down so much. Who knows if they would have gotten rid of them because of that. They were kinda ugly but in a cute way....that smile really did it! Why are the maintenance and operating cost higher? Why is it more complex than other jets? <Q> higher maintenance cost and higher cost of operations in compare to other jets due to its complexity. <S> That seems ironic considering what Wikipedia says <S> According to the BAe 146's chief designer, Bob Grigg, from the very start of the design process, making the aircraft as easy to maintain as possible and keeping operator's running costs as low as possible were considerably high priorities. <S> Velupillai 1981, pp. <S> 1245-1246, 1253. <S> Why is it more complex than other jets? <S> Because it has four engines? <S> I believe short-haul airliners of similar capacity mostly have only two. <S> Why are the maintenance and operating cost higher? <S> Wikipedia says of the original Lycoming engines used: <S> The ALF 502 has experienced multiple issues. <S> Its internal electronics could overheat, triggering an automatic shutdown of an engine with no option of in-flight restart, and certain rare atmospheric conditions could cause a loss of engine thrust due to internal icing.[29] <S> Additionally, the BAe 146 experienced aerotoxic syndrome due to leakage of tricresyl phosphate (TCP) into its bleed air; this has been blamed on problems with leaking engine seals. <S> Exposure to these toxic fumes is a dangerous health risk <S> Note: <S> the above is speculation, you'd have to ask an airline maintenance manager. <S> There are interesting maintenance anecdotes / whinges at pprune <S> High price of spare parts. <S> Accessibility of some components. <S> N1 harness that goes through engine fan strut. <S> Quick release fastners needed on engine core covers. <S> FADEC harness (RJ) can't be changed without dropping the donk. <S> Lower engine power cables that freeze full of moisture. <S> Corrosion issuse with the gear bay longeron strut. <S> The nose landing gear steering lube leaks out and the internals corrode Air con pacs are unreliable. <S> Honeywell apu's are unreliable, Garrets better. <S> Fuel tanks need proper draining off every day to get rid of moisture. <S> Tri-wing fasteners often fail on removal. <A> The reason is really the number of engines. <S> Engine maintenance is the biggest part of aircraft maintenance, and designers put as few on an airplane as they can get away with. <S> Two is the minimum for redundancy, and any more means more hours have to be spent in the shop. <S> This explains the 777 - it's the biggest thing Boeing could build once <S> the GE-90 was announced. <S> Why the 146 has four engines <S> is explained in the comment of @fsintegral below, but at least it helped to sell it in some cases. <S> Crossair used them because the owner, Felix Suter, wanted to have his own four-engine transport. <S> The nickname for the 146 at Crossair was Jumbolino. <A> BAE according to the accounts of a local Aircraft Engineer stood for "Bring Another Engine". <S> Engine reliability is was really was the death of this aircraft. <S> At least in my friends experience. <S> Their local examples were constantly having to be taken off line due to hangar time.
|
BAe sold the 146 for very low prices, so the saved money could cover the more expensive maintenance for some years.
|
Why are piggyback launches done by dropping the carried aircraft and not by "fly-off" launches? Every air-launched aircraft I'm aware of, with the exception of the D-21 in combination with the M-21 carrier, has been launched by dropping it. Is there a reason why drop launches are preferred to "fly-off" launches from the top of the carrier? <Q> Its much safer, you don't kill the carrier aircraft if you drop away and have a major aircraft malfunction. <S> Gravity gives you the separation you need. <S> If you treat the two aircraft like a formation flight, which it essentially is, its dangerous for the critical aircraft to go belly up, ie blind, to the carrier. <S> In an emergency the first step in formation flying is to ensure separation which the critical aircraft can't do because it can't see if it's clear to descend <S> and it may not have the ability to laterally sidestep. <S> Thus, a blind push on the nose could kill both aircrews. <A> The test launches of the space shuttle (both US and USSR) were top launches. <S> (though that was due to bulk more than aerodynamic considerations) <S> and it is easier to get vertical separation by dropping than by climbing. <S> With fly-off you start in the turbulent area and then need to get enough speed to fly, and stay in front or above of the launching craft until flight has stabilized. <A> If the plane is up the carrier and something go wrong, both planes crash. <S> The first test of the USA Space Shuttle were done with a carrier having the shuttle on its top; it was for wind tests. <S> A carrier having a plane to drop of a plane to take off from a carrier was tries to reach space at lower cost, planned in the 1970s and the tests done in the 1980s. <S> A model with reservoir was chosen instead.
|
Drop launches get you out of the wake of the carrier faster
|
Is there a benefit to having the motors for a multi-rotor copter on the top vs the bottom of the frame? There is a new quadcopter being launched on Indiegogo that has the quadcopter motors positioned on the top of the propellers as opposed to being positioned on the bottom. Is there any advantage to this or is it just for looks? <Q> It could be just for looks, but rotor placement has a noticeable effect on the behaviour of the quadcopter. <S> The higher the rotors are on the frame the higher the center of lift will be ( <S> the center of lift for quadcopters is the center of the plane created by the rotors.) <S> A high center of lift means that the frame will be more stable. <S> A low center of lift means the opposite. <S> The reason for that is that the quadcopter can better naturally deal with lateral rotational forces on its frame. <S> The center of lift being above the center of mass means that the frame is "hanging" like a pendulum from it. <S> If you apply a lateral force to it, it will naturally swing back to place and the more you push the "harder" it becomes to move the frame. <S> A center of lift that is in the same spot as the center of mass of the frame means that there is no pendulum effect. <S> This is like balancing a ball on top of another ball. <S> All lateral forces, either internal like variations on each rotors' force or external like wind perturbations have maximum effect in moving the frame. <S> Contrary to what you might think, stability is not something you want in a quadcopter. <S> The more unstable the frame, the more agile <S> it becomes. <S> Small variations in rotor force will create large rotational movements. <S> The penalty you pay for that (small, unpredictable external forces also create large rotational movements) you make up with processing power. <S> Processors are now so fast and sensors so sensitive that they easily can compute the external forces and create a response fast enough to keep the frame flying. <A> The main reason is related to how the arms impact the thrusters' aerodynamic efficiency. <S> It's actually quite surprising that most multi-rotors do not have downward-pointing props. <S> One reason might be that it becomes more difficult to mechanically implement the landing skids with downward pointing props. <A> @abey is right, but his answer is a little short. <S> Let me give some background. <S> Propellers work by accelerating air. <S> If you think of a stream tube through which all air flows that will pass through the propeller disc, the diameter of this tube is bigger than the propeller diameter itself ahead of the propeller and smaller behind it. <S> Since the air flows faster behind the propeller, the same mass flow needs less stream tube cross section. <S> The propeller sucks air in, so the speed increase starts at some distance ahead, and raises pressure in the disc, so more speed increase follows behind the propeller when the pressure $p$ in the streamtube falls to the level of ambient air pressure <S> $p_{\infty}$. <S> A strut placed ahead of the propeller will see less dynamic pressure than one placed behind it. <S> Turn the picture above by 90° anticlockwise, and you have a quadcopter propeller arrangement. <S> Make the initial speed $v_{\infty}$ zero <S> and you have the situation for a quadcopter in hovering flight. <S> Consequence: Propellers below the strut will have a higher efficiency. <S> Full disclosure <S> : The picture above is idealized - in reality, the air behind the propeller will mix with air surrounding it, which will be dragged along. <S> The streamtube idealization gives an easy way to calculate propeller thrust when combined with the assumption of identical air speed over the cross section of the stream tube, but in reality the speed distribution is uneven, with a gradual decrease with bigger distance from the axis of symmetry.
|
The impact is lower when the arms are on the air-intake side of the propeller rather than in the downwash.
|
Are there ever temporary flight corridors? A recent question on FAA handling of evacuations prompted me to wonder if there are ever temporary (emergency based) flight corridors set up by any of the governing authorities? For example, is there ever the airspace equivalent of one way highways set up for a temporary period? <Q> Flight corridors (airways) are just standard routes to simplify communication from controllers to pilots when describing where they should fly and between controllers when handing over flights. <S> But the controllers can assign arbitrary vectors (headings and altitudes) to aircraft whenever they see fit. <S> So there is no need to formally set up a temporary corridor. <S> If the traffic for whatever reason does not fit the usual corridor, the controller will simply assign any free vector and explain the situation to the next controller. <S> They do that all the time anyway. <S> However in non-radar environment <S> (e.g. oceanic or in case of radar failure) <S> airways become important tool for the air traffic control, because it would not be feasible to keep track of positions of all the aircraft on ad-hoc routes. <S> With airways the controller knows which airways intersect so planes on them need to be separated vertically and only needs to track the aircraft progress in one dimension (along the airway) instead of two (on map). <A> There aren't temporary flight corridors, but during emergencies, the FAA will issue temporary flight restrictions (TFRs), many of which include the following text: ALL AIRCRAFT ENTERING OR EXITING THE TFR MUST BE ON A DISCRETE CODE <S> ASSIGNED BY AN AIR TRAFFIC... <S> AIRSPACE CONTROL (ATC) FACILITY <S> AIRCRAFT MUST BE SQUAWKING THE DISCRETE CODE AT <S> ALL TIMES <S> WHILE IN THE TFR. <S> ALL AIRCRAFT ENTERING OR EXITING THE TFR MUST REMAIN IN TWO-WAY RADIO COMMUNICATIONS WITH ATC. <S> The controllers will then direct traffic in, out, and within the area as needed. <S> Also, remember that aircraft separation is by altitude as well as position, and nothing prevents a controller from using all the altitudes in her airspace to vector aircraft in one direction. <S> When assigning an altitude that contradicts the hemispherical rules, ATC will use the words "wrong way" to make sure you understand you are being given an altitude inappropriate for your direction of travel. <A> Corridors are only necessary for busy routes, and even then it's not mandatory for them to be used by ATC - it's just sensible to use them most of the time to avoid confusion
|
You could argue that any time an aircraft is given a route which is not on a permanent air corridor, a temporary one is set up, and that if a controller gives several planes a similar route, that corridor is in use More sensibly, no - there's no need to, there's plenty of airspace in areas with no corridors, and even if there was an unusual amount of traffic the controller would just implement a similar concept (routing aircraft along a similar route in the same direction) on an ad-hoc basis as and when required - there's no need to declare it as a corridor in some official manner and propagate that information to airlines and pilots.
|
Why did Air France retire Concorde? It was developed by British Airways and Air France in the 1970s as the first supersonic passenger/civilian airplane. <Q> Ultimately the cost of flying the aircraft was more than the revenue that it generated. <S> Even with the best safety record in airline history, the crash combined with the terrorist attacks led to passenger fear and low sales. <S> To make matters worse, it was very limited to which airports it could fly to in the US: <S> JFK, IAD and DFW. <S> The FAA was opposed to the Concorde for pollution, noise and fuel inefficiency concerns. <S> British Airways cites mostly political reasons for the ending of its Concorde program. <S> They claim that the Concorde would have remained profitable had Airbus retained the airplane. <S> However, there was also speculation that, due to the dwindling numbers of passengers, BA realized that it could make more money carrying passengers subsonically across the Atlantic. <A> Why did Air France retire the Concorde <S> It wasn't making money - in fact, it was losing money. <S> Huge fuel price increases shortly after it was brought in meant it was never really profitable for Air France. <S> Then double-whammy of the Air France Flight 4590, followed a few years later by 9/11 hitting Airlines hard in reduced passenger numbers (particularly into New York), caused Air France to consider it no longer viable to run even as a loss-making flagship service. <S> Why did British Airways retire the Concorde A related but separate question, BA actually found a way to make their Concorde's profitable later on. <S> They discovered that the public (particularly the business users who weren't paying for their own tickets...) thought Concorde tickets were more expensive than they actually were, so merely increased the price to match. <S> They were profitable for several years until Airbus announced they were no longer going to maintain or support the aircraft. <A> The Concorde did fly for several years, but it couldn't fly supersonic over land (as Steve pointed out, it was able, but not allowed due to concerns about the sound of the sonic boom) and it guzzled fuel. <S> In the end, it wasn't economically viable.
|
Airlines that operated the Concorde eventually lost money on most flights, and long term operations were simply not sustainable. The Concorde began a steady decline to retirement after the firey crash of Air France Flight 4590 which killed 113 people, and again suffered setback after September 11th, 2001.
|
Can a fighter jet land on a modified airliner? Imagine this scenario: A modified military 747 is flying at a constant speed and altitude. On the top of the fuselage there is a device like a helipad but with three holes to accommodate the fighter jet landing gear, when pressure is applied the holes close, locking the landing gear in the holes. The fighter is flying at the same speed and slightly above. With proper training, is it possible for the pilot to land on the plane and then shut off the engines? <Q> Technically yes. <S> But I am unaware of any attempt to do this with airliners. <S> But there were several designs in the past which used a big airplane or a Zeppelin as a mother ship, which took fighters with it for air defense. <S> The B-36 was involved in several such designs. <S> In all cases the docking was made from below, because this gave the fighter pilot the best field of view and reduced the risk of a tail strike. <S> While the fighter in the picture above is a Republic F-84, McDonnell even designed one specifically for the purpose of being carried around by a bomber, the XF-85 Goblin . <S> It used a rather complicated trapeze for docking and was then pulled up into the fuselage, as the picture with a B-29 below shows. <S> But when you change the airliner to a AN-225, the idea looks not totally impossible. <S> The Russians tried to dock a fighter with a mothership as early as the 1930s. <S> The picture below shows a TB-3 docking with a I-Z fighter, the first pair of aircraft in history to dock in flight. <S> The main reason for docking was the much smaller range of fighters. <S> Today, air refuelling takes care of this deficit, so it is unlikely that anyone will see a benefit strong enough to justify the expense of modifying two aircraft and the risk incurred in the docking process. <A> Parasite jet aircraft have been experimented with, the only purpose built one <S> I know of is the XF-85 Goblin <S> , there was also a modified F-84 Thunderjet which was used as well. <S> These experiments were abandoned because the process of launching and recovery was too hazardous, and air to air refueling made much more sense to extend the range of fighters. <S> It is possible to join 2 aircraft in the manner you describe, however it's extremely dangerous due to the aerodynamic forces involved, and there are no benefits which would make the risks worthwhile. <A> It is not possible to replicate this process safely. <S> The pilot in the smaller aircraft can not see its gear and would have no idea where to "land". <S> And perhaps even more importantly, there's no out if the fighter has an emergency. <S> If the fighter loses control just above the carrier then its likely that both aircrews will die. <S> As has been pointed out in other posts, aircraft have been recovered underneath carrier airplanes in the past, and while dangerous, this leaves an obvious escape route in the event of an emergency. <A> DARPA just happens to be asking for proposals on how to accomplish this very task: DARPA invites input on how to enable existing large aircraft to carry, launch and recover multiple unmanned air systems for a variety of missions <A> The idea was that the additional wingspan would increase the range of the bomber, while at the same time enable it to carry its own fighter escort which could attach and detach in the air as required. <S> While attached the fighters could switch off their engines, thus saving fuel for later. <S> While attached, the B-29 would control the flight surfaces of the attached F-84 (more specifically EF-84D) so that the pilot wouldn't have to do this manually, but during the first flight with this system enabled one of the fighters rolled on top of the B-29s wing, and the two aircraft crashed with no survivors. <S> The second F-84 survived as it was disconnected from the B-29.
|
Your design proposal with the simple platform on top of the fuselage would carry a high risk of a tail strike if anything goes wrong, so it is unlikely that this will ever be tried for real. As an addition to the projects described by Peter Kämpf, there was the Tip Tow project during the fifties where two fighters were attached to the wingtips of a B-29.
|
Cessna 172/182: Should I set the tank selector to the R.H. tank after parking the airplane? The single-engine Cessna 172 and 182 aircraft models have a dual gravity-fed fuel system, where you can draw from both the LH and RH tank simultaneously in flight. I've heard it said that when you are securing the airplane after a flight to leave the tank selector on the RH tank to prevent crossflow if the ramp is uneven. (So you don't end up with all the fuel in one tank). Is there any merit to this? Does it actually block the crossflow valve to do this? <Q> The C172S manual I have says to set the selector to left or right as part of the "securing airplane" checklist: Fuel Selector Valve -- LEFT or RIGHT to prevent cross feeding <S> I was also taught to set it to right during my initial training. <S> The idea is to prevent cross-contamination or leaks if one tank is compromised. <S> Another reason is that if you park the aircraft on a slope, you could end up with an imbalance between the tanks, as you said. <S> So the POH confirms that it prevents cross feeding, at least in that model: you should always check the POH for your specific aircraft. <A> If you leave the tank on dual and you put fuel in the right tank by the time you are ready to put fuel in the left tank some of the fuel will have flowed into the left tank. <S> The right tank would have more pressure from the weight of the fuel than the emptier left tank and as any liquid will do <S> it will try to balance between the tanks. <S> You will end up with less fuel than 2 full tanks. <S> That is why the POH states either right or left tank. <S> It doesn't matter which tank, just that they are not connected when refueling. <A> My aircraft ( M20M ) fuel selector has left, right, off. <S> I taxi on the lower tank, then switch to the fuller tank to do the runup and take-off on. <S> That assures that both tanks feed fuel, and I'm always departing on the fullest tank. <A> Is there any merit to this? <S> Possibly. <S> Think of it like parking on a hill and leaving your car in gear <S> /steering into the kerb, in case the handbrake fails.... <S> it's a precaution, rather than a requirement. <S> In the case of a Cessna, the fuel tanks in the wings are very long, wide and flat - so it wouldn't take an excessive amount of bank to allow fuel to slowly move from one tank to the other. <S> If that happened to a great enough degree, in theory the fuel could adversely affect handling. <S> Chances are that the ramp isn't off-level enough to require it, but assuming that it does block the valve (I'd assume it does, as I'm not sure how else it would work) then there's little harm to be done, and some potential benefit in some circumstances. <S> Does it actually block the crossflow valve? <S> No idea, I don't own a C172: it seems like a logical conclusion, but I'd check your manual or with the manufacturer. <S> Just remember to turn it back to dual feed when you set off.
|
My technique (which would apply to any aircraft that doesn't have dual tank feed) is to turn the fuel off when it is parked.
|
Can you flag down / contact an airplane with a handheld radio in case of emergency? A friend and I are going rim to rim to rim in the Grand Canyon this Wednesday. It's a 46mi, 20+hr "hike" with some very physically challenging sections. We are packing the minimal amount needed - meaning not too much extra in case of an emergency - it's especially risky given the below zero (fahrenheit) temperatures this time of year. Normally for something like this, I would bring my Spot - to call for help if I needed to, but it's not working. If I brought my VXA-220 , would it be legal to use it to call for help? From what I understand, most airliners are tuned into 121.5. Could I tell them to send a helicopter for rescue? Obviously, in a life or death situation it's not going to matter if I'm braking the law. But it would be nice to know how such a situation would be handled. <Q> Yes, this is legal. <S> As far as I understand, it used to be common practice, and some hiker's beacons still squawk 121.5. <S> Nowadays, more advanced beacons are suggested, but it sounds like yours isn't working. <S> Some police and EMT stations still monitor 121.5, too. <A> Bear in mind that the effective transmission range of many handheld airband radios is pretty poor - typically rather worse than the reception range. <S> And despite the NOTAM requesting aircraft to monitor 121.5 "when able", many do not. <S> So while it's better than nothing, it's probably not a good idea to rely on this means of calling for rescue. <A> The question is pretty old. <S> This post is to add new info. <S> Since this question is about hiking, a PLB like one from manufacturers ACR or by Ocean signal would work well. <S> And, they are personal sized. <S> I believe they are both 121.5 and 406 dual transmitting. <S> The manufacturers include instructions and paperwork for registering them with SARSAT making them legal for emergency use. <S> You can also do this at: https://beaconregistration.noaa.gov/RGDB/index . <S> Handheld airband transceivers are notoriously weak. <S> If you already have the transceiver, and are determined to use it, a jungle antennae is your best bet. <S> See here: https://brushbeater.wordpress.com/2015/10/15/the-jungle-antenna/ <S> A PLB is still the first choice. <A> This answer is for the United States only. <S> 47 CFR § 87.43 states (in full): § 87.43 Operation during emergency. <S> A station [in other words, a radio set] may be used for emergency communications in a manner other than that specified in the station license or in the operating rules when normal communication facilities are disrupted. <S> The Commission may order the discontinuance f any such emergency service. <S> I'm not 100% sure that this really does allow operation if you don't have a radio license at all, but it certainly seems to. <S> (If you're not aboard an aircraft and the FCC hasn't given you a radio license, then you don't have a radio license at all.) <S> But it's only allowed "when normal communication facilities are disrupted." <S> So presumably, if you have a cell phone or satellite phone you can use to call 911, you're required to do that instead.
|
Unless you have a perfect day, or you know how to construct the right antennae for your frequency and environment, you would be better off with a rented satellite phone than a transceiver.
|
Has a commercial airliner ever crash-landed in an ocean? They have rafts and life jackets on board and before takeoff, passengers are explained how to use that equipment, but have any evacuations ever happened successfully? <Q> Yes, commercial airplanes have landed or crash landed in water many times. <S> If I am not mistaken, you are asking about scenarios when the on-board life jackets and life raft are used. <S> Here is a list of water landings. <S> Examples when a life raft was used are (in addition to ratchet freak's mentions ): <S> On 22 October 1962, a Northwest Airlines DC-7C with 7 crew and 95 passengers made a successful water landing in Sitka Sound. ... <S> The plane stayed afloat for 24 minutes after coming to rest in the water, giving the occupants ample time to evacuate into life-rafts. <S> All of the 396 occupants donned life-vests, boarded the eight slide/rafts and no fatalities resulted. <A> Yes - it happened in 2009 in the Hudson (well it's a river), and it happened in 1996 Ethiopian Airlines Flight 961 as far as I know. <A> Yes. <S> A Cathay Pacific DC-4 <S> (technically a C-54) was shot down by Chinese fighters off the coast of Hainan island on 23 July 1954. <S> With his rudder and right aileron shot off, fuel tanks on fire, and the #4 engine down, the pilot ditched into the ocean. <S> Of the 19 people on board (including 3 flight crew and 3 cabin crew,) 9 died either from bullets or the ditching into the ocean. <S> The remaining 10 floated in the water for a while and then inflated and boarded one of the rafts. <S> The passengers remained on board the raft for several hours until a USAF SA-16 Albatross flying boat was finally able to find a spot were it could land on the rough seas, then taxied to the raft and pulled everyone on board before taking off and flying to Hong Kong. <S> A passenger who had been badly injured died en route to Hong Kong. <S> The remaining 9 people survived. <A> Yes there have been several such instances. <S> To name a few, some of which were captured on camera: Ethiopian Airlines Flight 961. <S> You can see the actual crash landing video here . <S> 125 of the 175 passengers and crew on board died. <S> US Airways flight 1549. <S> The video was caught on a cctv video . <S> All passengers and crew were safe. <S> Tuninter Flight 1153. <S> 23 out of 39 survived. <S> No film exists but it was dramatized in a Mayday episode here . <S> There have been many other evacuations, some successful and some not so successful. <S> You can get a detailed list here . <A> I'm not sure if this fits in with "commercial airline", but there was also a Cessna 208 "Grand Caravan" that crashed just off the coast of Kalaupapa, Molokai, Hawaii about a year ago on December 11, 2013. <S> It made an emergency landing into the Pacific Ocean after the engine failed just after take off. <S> The aircraft was chartered by <S> Makani Kai Air to deliver passengers from Kalaupapa to Honolulu . <S> One person (a state health department director) was killed in the crash. <S> The crash was also captured on video with a GoPro camera by one of the passengers. <A> One more for you: an SAS DC-8 crash landed in Santa Monica bay in January of 1969. <S> Most of the crew and passengers survived, using the on-board life rafts. <S> There were some issues as two of the rafts were punctured by debris. <S> The survivors (30 out of 45 aboard) were rescued after about an hour. <S> The cause was controlled flight into terrain resulting from flight crew failures and a series of issues including an inoperative nose gear light which distracted the crew. <S> The tail struck first and broke off, sinking immediately. <S> My dad had been a purser for the airline in the late 1940s and I remember him telling me that one of the victims sitting in the crew seats in the tail was an old friend with whom he had flown. <S> My dad was pretty upset to lose a friend this way. <A> ALM Antillean Airlines Flight 980 was a flight scheduled to fly from John F. Kennedy International Airport in New York City to Princess Juliana International Airport in St. Maarten, Netherlands Antilles, on 2 May 1970. <S> After several unsuccessful landing attempts, the aircraft's fuel was exhausted and it made a forced water landing (ditching) in the Caribbean Sea 48 km (30 miles) off St. Croix, with 23 fatalities and 40 survivors. <S> The accident is one of a small number of intentional water ditchings of jet airliners <A> Pan am flight 6 often mistakenly called flight 943 crashed in the Pacific Ocean half way between Honolulu and San Francisco. <S> All 24 passengers and 7 crew members were rescued by the coast guard and survived. <S> The crew members on the pontchartrain are true heroes. <S> My father was on of them. <S> The incident happened October 15th 1956. <S> They lost 2 of their 4 engines around 3:00 a.m. they flew circles to burn off fuel and wait for daylight. <S> They hit the water at 8:15 a.m.. <S> the plane split in half but Coasties were there within minutes.
|
In 1993, China Airlines Flight 605 , a Boeing 747–409, ended up in water after it overran runway 13 ...
|
Why don't airlines provide smoke hoods? In Fire-involved Accidents and Incidents Reviewed , Rudolf Kapustin stated in 1993 that Nearly all aircraft accident fatalities that are not the result of crash/impact injuries are the result of post-crash fires and the inability to exit aircraft quickly, which in most cases is attributed to incapacitation from toxic smoke, fumes or injuries. This makes me wonder why airlines don't provide smoke hoods for their passengers in case of a fire, the same way they provide life vests in case of a water landing. If flights crossing a body of water must have life vests available for all passengers in case of a water landing, why not make an equivalent law for smoke hoods in case of a cabin fire? Protective breathing equipment, or smoke hoods are protective head coverings that prevent wearers from breathing the smoke, particulates and toxic gases generated in a fire. There are two main types of hoods: those that have a source of breathable air and those that just filter the particles out of the air. The smoke hood for aircraft passengers wouldn't need to be a firefighting grade smoke hood, just enough to get everyone out of the plane before they get asphyxiated. Today, the recommendation in case of a cabin fire is to stay near the ground where the air is more breathable. If passengers could be equipped with smoke hoods, they could walk out instead, which would likely make an evacuation faster. Granted, the smoke hoods would be used on rare occasions, they have a cost, take up space, weigh something, and you have to explain to the passengers what to do with one in case an accident happens. So it is unlikely that an airline would spontaneously decide to equip all seats with an emergency smoke hood. But life vests have all of those disadvantages as well. It seems to me that these hoods would not be any heavier or any more expensive than the life vests, and might be used on more occasions than the life vests. I've seen smoke hoods the size of a soda can, so finding a place to fit one on each seat can't be so hard. So why aren't plane equipped with emergency smoke hoods for passengers? <Q> This is an issue on airline passenger safety that has been debated since a very long time, and there are various arguments for and against the use of smoke hoods. <S> A classic example which showed the requirement for smoke hoods was the British Airtours Flight 28M, which had an engine failure during its take off roll at Manchester International Airport in August 1985. <S> The ensuing fire and black smoke made the evacuation very difficult, and as a result 48 people died from smoke inhalation. <S> Perhaps, the presence of smoke hoods could have saved many more lives. <S> But at the same time, the subsequent investigation revealed there were other factors which contributed to the tragedy, such as the restricted access to exits and standard operating procedures which did not take into account the wind direction before turning. <S> From what I have read and researched, smoke hoods might involve unnecessary time wasted in wearing them. <S> After all, airline crews are trained to evacuate a passenger aircraft within 90 seconds with half the emergency exits blocked. <S> This time is considered sufficient to escape toxic smoke related fatalities. <S> Secondly, the passengers might require some detail as in how to use them. <S> Surely, space, weight and cost issues are secondary and can easily be overcome, but these are other issues which prevent their use. <S> In case of a fire upon crash landing, the immediate action is to evacuate and go as far away as possible from the aircraft. <S> Since the passenger will not be staying in the smoke, it does not seem logical to provide smoke hoods. <S> A water landing on the other hand might require passengers to float on the water surface for some time till emergency services arrive. <S> This necessitates the need for a life jacket, otherwise lives can be lost due to drowning. <A> Factors that airlines are likely to consider extra cost and weight of equipment additional time and cost to check equipment regularly still present after each flight in good working order regularly need to instruct passengers <S> need to supply boarding parents with specialized devices for infants and small children and provide extra instruction <S> fatalities may rise due to inevitable incorrect use ( example ) what happens when the panicking passenger by the exit puts their hood on back-to-front? <S> how to introduce intrusive and effective instruction without increasing fear of flying? <S> Every new airplane model must receive a 90-second evacuation drill certification from the FAA before it can fly. <S> Can this be done wearing hoods? <S> In what circumstances are flight crew likely to instruct passengers to don hoods? <S> How likely are passengers to be incapacitated before they can find and complete donning of smoke hoods? <A> Another relevant point is that a fire in a confined space can use up all the oxygen in the air very quickly so, for a hood to be useful, it probably has to include its own oxygen supply.
|
But, now, you've increased the amount of oxygen within the plane's fuselage so the hoods might actually make the fire worse and all the people who would have died from smoke inhalation might just end up dying from burns instead.
|
How does one launch unmanned high-altitude balloons without posing a safety risk to aviation? How can people launch balloons privately (filled with helium or hydrogen) that reach the altitude of 30,000 feet? Isn't that a safety risk in the same way as geese? <Q> An aircraft could collide with the balloon itself (as described in the case <S> that Jan Hudec posted in his comment), or with the balloon's payload (see the FAA's AIM section 7-5-4 for general comments on this). <S> But it's important to note that unmanned balloons are (or should be) launched only after appropriate preparation and communication; most countries have some sort of regulations to follow. <S> In the US (for example), 14 CFR 101 governs unmanned balloon launches and it includes the following requirements: Launches must be in (mostly) clear skies and away from airports and built-up areas <S> The balloon must have a radar reflector and lights (if launched at night) <S> ATC must be informed in advance of the balloon launch, expected path etc. <S> The operator must track the balloon's position and descent and report them to ATC as needed <S> In other words, the balloon should be as visible as possible - both visually and on radar - and ATC should know where it is. <S> That gives pilots a way to see and avoid the balloon and ATC can provide warnings and/or avoidance instructions to aircraft directly where possible, which is actually fairly similar to how aircraft avoid other aircraft. <S> Of course, there may be cases where someone launches a balloon without following those rules (or the local equivalents in another country). <S> That would create a much higher safety risk but it would be illegal and the operator would be risking penalties for doing it. <A> High altitude balloons reach more like 30km rather than kft. <S> This means that there's a limited time in which they can interfere with normal aviation traffic (which, during cruise, is usually in a fairly narrow band between 8-12km). <S> Outside of cruise can be more of a problem (i,e: <S> When landing or taking-off). <S> For that reason it's essential to launch from somewhere far from an airport, so that the balloon can ascend in a location where it will not affect air traffic. <S> Most countries also require you to inform air traffic control in advance of a balloon launch so that they can issue a warning (NOTAM) to pilots that lets them know to be aware of balloon activity. <S> Lastly, one can reduce the risk to aviation by constructing the balloon payload carefully. <S> The balloon itself doesn't pose much of a risk but a heavy/dense payload can. <S> To reduce the risk lightweight components should be used and dense items like batteries kept to a minimum. <S> Most countries also have rules governing the size and weight of the balloon that you can launch. <S> For balloons that can't meet the rules (too heavy, need to launch near an airport, etc) <S> there's two choice: <S> 1) Don't launch.2) <S> Perform a much more extensive risk analysis and actively divert air traffic away from the balloon. <S> This requires air traffic control to be able to see the balloon (using a radar reflector or, more usually, a transponder). <S> Because of the cost of this option it's normally only very important or high-value payloads that are sent this way (such as NASA's research balloons). <A> As for the TAM flight, that does not sound like a High Altitude weather balloon. <S> That sounded like an unmanned hot air balloon carrying a big banner. <S> I am guessing, based on the article that it was designed to stay at a lower altitude so people could see the banner. <S> High altitude weather balloons are like giant party balloons, very thin latex usually. <S> They generally rise at 1000 ft/min and are out of busy airspace quite quickly. <S> The payloads are limited to 12 lbs, but usually much lighter. <S> Mine was just over 2 lbs. <S> If the regulations are followed there is very little risk. <S> Good luck, do your research, and have fun. <A> High altitude balloons going into commercial airspace that are large enough to be a threat to a plane require a NOTAM to be issued and <S> even small balloon launches are encouraged to have a NOTAM. <S> Also, a weather balloon will not spend very much time in the danger zone but will drift right through it, so the exposure is brief. <S> Most commercial fights occur along well-known corridors and flight paths. <S> Balloons are often launched far away from those lines of travel. <S> Just that alone makes it pretty safe. <S> Small planes do the same thing: stay away from commercial flight corridors.
|
Unmanned balloons can indeed create a safety risk for aircraft.
|
Why are vertical stabilizers always at the rear of an airplane? Sharks and whales have them in the middle of their body, so why not planes? <Q> With sea creatures the dorsal fin acts as a keel providing the actual sideways force during the turn. <S> They remain level while turning. <S> Planes on the other hand bank to turn where the sideways force is provided by the lift of the wings. <S> To provide yaw stability the vertical stabilizer should be as far from the center of mass as possible. <S> They are not in front because that would be unstable as the minor deviation from straight ahead would increase the force into the deviation rather than provide a force to counteract it. <A> The vertical stabilizer is for "stability". <S> Try throwing a paper airplane or a dart backwards, and watch how it flips around due to this stabilizing force to have the stabilizer in the rear. <A> To add to other answers, vertical stabilizers also have control surfaces on them, and in order to maximize the effect of those control surfaces, you have to have them as far out from the center of horizontal rotation as possible. <S> Why not in front: Stabilizers create drag. <S> Drag is pulling backwards. <S> When they are in the back, that's a natural resting point for them and thus they actually try to keep plane stable in one direction. <S> Move them to the front and you would get a force that constantly tries to turn you butt-first :) <S> Example you can try at home: <S> Imagine a swinging door. <S> The closer you move the door handle to the hinges, the more force is required to open the door. <S> same applies to the airplane. <S> If you place the rudder in the middle it will mostly push plane to the side instead of turning it.
|
By having it aft of the center of gravity, it will generate a side force that will correct out any undesired yaw.
|
What is the rule of thumb for land/taking-off on a sloped runway? Skyvector lists the gradient for KMCI as 0.3%. What is the rule of thumb for how large a gradient needs to be before you always take off downhill and always land uphill like they do at Lukla ? Assume winds are not a factor. <Q> What does your POH/AFM says? <S> Ignoring winds and other factors, it depends on effective runway length , not just runway length. <S> If you have a runway long (really long) enough, you can takeoff/land in either direction. <S> As mentioned here : <S> ... advantage or disadvantage of a sloped runway is that a 1% runway gradient — an increase or decrease in altitude of 10’ for every 1000’ of runway length — is equivalent to a 10% increase or decrease in effective runway length ... <S> Example: Runway length is 1500' with 3% up-slope gradient Landing uphill on it will give us an effective runway length of almost 2000’ (1500’ x 1.3 = 1950’). <S> Landing downhill on it will give us an effective runway length of just over 1000’ (1500’ x 0.7 = 1050’). <S> Just for reference, the runway (6: uphill; 24: downhill) at Lukla Airport has 12% gradient and is 1500' long. <S> Effective Runway Lengths (using the formula above) 6: 1500' <S> x <S> |(1+ <S> 1.2)| = <S> 3300'24: 1500' <S> x <S> |(1-1.2)| = <S> 300' Hence, hypothetically speaking, if runway 24 is 48,400' long with no wind, A380 can takeoff too. <A> I happened to be looking at some takeoff distance charts, so I looked into this. <S> As Tyler says, the answer will depend on your airplane's performance. <S> With good brakes and plenty of runway, a small plane may not care as much as a larger one. <S> The following applies to the PC-12. <S> I know you said to assume winds are not a factor, but it may help to roughly relate the effects of slope and wind. <S> It turns out that 4% of slope will either help or hurt about the same amount as 10 kt of wind (within about 7%). <S> Both provide around 10% benefit or 25% penalty on takeoff distance, and landing distance is affected by slope a bit less and wind a bit more. <S> This would provide a good sense of how much a slope will affect the runway length you need. <S> That penalty will certainly start to hurt as slope increases. <A> There is no firm guideline. <S> I have landed at Jaffrey only uphill, which has a 0.9% grade and a bad surface, but people can and do land there downhill. <S> It is very steep for an air strip. <S> If the wind was strong enough I would have no problem landing downhill there, but with moderate winds I would always go uphill.
|
It depends on wind conditions and other factors like the surrounding terrain.
|
What is the rationale behind "One engine - Two propellers" configuration? I stumbled upon a very unusual Russian amateur built ultralight: One engine, two propellers configuration My first impression is that it adds another useless layer of complexity and moreover it may involve some safety issue: I particularly think of the entry into a spin in case of one propeller failure. What is the rationale behind it? The pros and cons? <Q> It looks as if they rotate in opposite directions. <S> This eliminates prop torque , which should improve handling, especially at low speeds. <S> On the other hand, you are right with your impression that it adds complexity, but at least it is not completely useless. <S> Asymmetric prop failure is indeed an issue and will markedly reduce handling qualities, and for that reason both props are close together, so if one is left, the yawing moment should be manageable if the craft flies fast enough. <S> Putting a single prop in the center would present it the messy flow coming from the unfaired cockpit and engine, so placing them left and right should improve inflow conditions. <S> They are still close enough so the tail is in the prop wake and will have improved effectiveness at slow speed and on the ground. <S> On the other hand, the outriggers will create additional drag, and it is hard to say if this arrangement will have performance benefits. <A> Basically it allows the benefits of multiple propellers with a single engine. <S> At low powers increasing the number of engines decreases power-to-mass ratio. <S> Additionally, the builder might simply have had only one engine available or affordable. <S> Removal of prop torque, as mentioned in the accepted answer, is a clear benefit. <S> Probably relevant for this particular ultralight, having larger propeller area at limited height. <S> In the design in the image the height is especially limited. <S> Also not having the propellers in the same line with the body probably improves air flow slightly. <S> I think the limited height available in the design is the actual main reason. <S> It is slightly more mechanically complex than single prop, which increases weight and chance of failure. <A> While the currently accepted answer would be valid in terms of eliminating prop torque had that been the setup, a close look at the photograph shows both propellers rotating in the same direction (counterclockwise from the point of view of the viewer) - the pitch of each blade is clearly visible. <S> I would suggest that in this application, the two propellers are used to give the benefit of an equivalent larger overall propeller (greater propeller area), without the additional ground clearance or vertical space requirements - a larger propeller puts through more power for the same engine RPM.
|
Generally having larger propeller area for power improves efficiency and reduces noise.
|
Do fighter jet pilots ever use autopilot? I know that military jets have autopilot, but do the pilots actually prefer to use it? I ask this question because, unlike civilian airplanes, military jets are more likely to come in a situation where the pilot may have to take quick decision and leave the designated path for some mission (e.g. to intercept a civilian jet flying on a wrong path). In such case, the autopilot may become a problem for quick maneuvering. <Q> I'm not in the military, so you could say I'm talking out my rear end here, but based on my experience as a pilot: <S> yes, military pilots use the autopilot all the time . <S> Here's my reasoning, in order of most to least convincing evidence: <S> Punching the autopilot off takes about a fifth of a second . <S> The button is right there on the yoke, for crying out loud. <S> The time it takes to turn it off is not a good reason not to have it on. <S> The autopilot is a labor-saving device. <S> When you're in an aircraft (and particularly when you're solo in one) there are times when you'd rather be paying attention to your chart or setting up the FMS or stretching or eating a candy bar instead of actually flying the plane. <S> Also, when Air Force pilots fly long repositoning flights, the autopilot reduces fatigue between in-flight refuelings (the Navy uses carriers). <S> Times when you might have to leave the designated path for a mission happen a lot less than you think. <S> Again, not in the military, I'm just basing this on the realities of fuel and the number of military aircraft out there. <S> Maybe if you're flying close air support for teams on the ground or something, but remember that the military is first and foremost a logistics organization - it's a machine for moving people and things from one place to another. <S> Most of the time, military aircraft aren't on a hair-trigger moment's notice ready-to-engage posture, they're going from one airfield to another for training or maintenance or something. <S> In most aircraft, you can override the autopilot if you need to anyway. <S> Again, never flown a military fighter aircraft, but based on what I know about flying in general, even if you're chilling in your F-22 (with the autopilot on) if you grab the stick and yank, the airplane will move. <S> ( I would be interested to know whether this is true of Airbus aircraft. <S> EDIT: <S> Question answered after 4 years!) <A> Military pilots are not unlike most other pilots: we're lazy and love booze, and we become just as autopilot crippled as the next guy. <S> Fighter aircraft controls are designed around the HOTAS philosophy, or hands on throttle and stick. <S> To quickly perform flight critical functions, like disengaging the autopilot, the pilot's hands do not even have to move from the controls. <S> On the Super Hornet the preferred method to disengage the autopilot is to paddle it off with the pinky finger on the stick. <S> However, 5 pounds of pressure on the stick will also disengage the autopilot. <S> Furthermore, some autopilot functions of the super hornet are always on. <S> For instance, the jet constantly trims itself to 1 G and this autotrim will relatively help maintain a stable platform. <S> Aside from laziness, there are times when the autopilot can be a large asset to the mission. <S> The cockpit of a fighter aircraft can get very busy when transitioning between phases of flight. <S> Here are a few mission related examples off the top of my head when having some form of autopilot is really nice: <S> When leading another aircraft (it makes it easy for the wingman if you are stable) <S> When flying parade and trying to do anything besides flying parade. <S> Flying parade sucks. <S> Configuring mission related instruments <S> Performing coupled approaches to the boat (scary) <S> There are as many, if not more, reasons to use the autopilot in a fighter aircraft than in our civilian counterparts. <S> However, as you rightly assume, when we are flying dynamically (ie, low levels, BFM, bombing, etc), the AP is disengaged (save autotrim), and the pilot controls the aircraft. <A> Sure, fighter pilots use autopilot quite a bit. <S> Disengaging the autopilot is as simple as hitting a button in some aircraft, or just moving the stick in others - it won't slow reaction time or prevent a pilot from responding to some event. <A> The other answers cover almost everything, but one point that hasn't been mentioned is that the auto-pilot isn't just a labor-saving device, or even a focus-saving device: it reduces human error. <S> Of course trained pilots, especially combat veterans, can fly extremely reliably, but humans are humans, they can make mistakes and simply engaging the auto-pilot between refueling points on the way to the mission zone and back will get rid of that possibility.
|
Using an autopilot reduces fatigue on long flights and frees the pilot to navigate, manage systems, and keep a lookout for threats.
|
For an FAA commercial license, can I use EASA/ICAO 2nd class medical? I have an FAA 3rd class and EASA 2nd class medical. On my EASA 2nd class medical it says "This medical certificate complies with ICAO standards". To obtain an FAA commercial pilot license, will I need to re-take the 2nd class medical by FAA standards with a different AME or does the FAA accept an "ICAO compliant" medical? <Q> You can "obtain" an FAA Commercial Pilot Certificate with a Third Class Medical Certificate; the Second Class Medical Certificate is only required to be able to "exercise the privileges" of a Commercial Pilot. <A> There's no provision in the FARs for using a foreign medical in place of an FAA one. <S> The only place it's mentioned is under 14 CFR 61.75 , where you can apply for an FAA foreign-based private license using a foreign license and medical. <S> But you don't need a second-class medical to get a commercial license, you only need it to exercise commercial privileges (see 14 CFR 61.23(2)(ii) ). <A> FAA medical certificate requirements are : <S> Medical certificates are designated as first-class, second-class, or third-class. <S> First-class is designed for the airline transport pilot Second-class for the commercial pilot Third-class for the student, recreational and private pilot Coming to your question, <S> this site states (my highlighting) : ... <S> the ICAO naming structure for the various classes of medicals does not fit with that of the U.S. <S> Under the ICAO definition, a second class medical applies only to holders of private pilot licenses . <S> In most States, outside of the U.S. and Canada, it is easier to simply carry a valid first class medical rather than trying to explain to a foreign inspector that a FAA second class medical equals an ICAO class <S> 1 medical . <S> For more information, please read this PDF .
|
If you just want to get the commercial license as a personal training/development achievement then you can use your existing third-class medical, but if you plan to use your new privileges then you do need a second-class one.
|
Is it OK to move a light aircraft by pushing or pulling the propeller? It's very common to see pilots moving a light aircraft by pushing or pulling on the prop, either because there's no tow bar available or simply out of preference or convenience. Is this a reasonable thing to do or can it damage the prop or engine in some way? <Q> A couple of my CFIs have asked me to help them park the airplane (in absence of a tow bar) when I was pushing the airplane by putting one hand on the hub and the other on the propeller near the hub, and them (the CFIs) pushing the tail down and nose wheel elevated. <S> But according to AOPA , it is not a good thing: ... <S> never push or pull on the prop blades. <S> Forget what anyone has told you about pulling near the hub or the strength of the propeller. <S> Aluminum blades can bend, and it doesn’t take much to put the blades out of track with one another. <S> This PDF says the same thing: <S> Avoid pulling the airplane around by the prop. <S> Yes, this seems the perfect solution to a vexing problem of how to change the airplane’s position without having to walk around and get the tow bar, but it’s worthwhile to make the extra effort. <S> Neither the engine nor the prop particularly benefit from the loads imposed by horsing the whole airplane around. <A> Classic example of one corner case leading to a blanket belief. <S> Grabbing a propeller by the tip, especially a wooden prop, can cause damage. <S> In use, the tips generate most of the thrust but are also held straight by the rotational forces. <S> If you grab the prop on both sides the airframe won't know that the engine isn't running. <S> So, here's a Rule of Thumb: if you cannot touch the prop hub with your thumb while pulling on the prop, you are holding it too far out. <A> Well, grabbing the propeller at the blade root and pulling from there cannot hurt it. <S> Why? <S> Because the thrust imparted by the propeller to the aircraft is applied at exactly the same place. <S> In other words, the propeller pulls the airplane through the air at the hub. <S> You are so close to the hub that you're not going to create a significant bending moment along the blade. <S> On the other hand grabbing the propeller at the tips would be questionable at best, and ill-advised! <A> I asked around at my gliding club about this, the consensus seems to be that it won't harm the plane as long as I didn't use excessive force. <S> The reason for doing it is to not have to walk from wing to wing to move the plane. <S> The main counterpoint is that you shouldn't move a plane by yourself unless you're very sure you won't hit anything (another plane, the hangar walls, etc). <A> By deviating from the standard procedure (using the tow bar) you incur into the following risks: <S> Mechanical damage: you risk damaging propeller itself if you don't pull from as close as possible to the hub. <S> Furthermore, being more complex, variable pitch blades obviously imply more risk. <S> Arguably, the forces in play during taxiing are similar to those exerted manually through pulling. <S> Also, in my flight school, during pre-flight inspection we actually perform some push/pulls to assess that the propeller, hub, and drive are ok -- suggesting that there is no mechanical stress derived from doing so. <S> Safety risks: although arguably rare, you may accidentally start the engine through hand-swinging. <S> I was instructed in my flight school to shut down the engine through the mixture control mainly to prevent this from happening during the pre-flight inspection previously described. <S> This is also why we perform magneto ground checks during shutdown. <A> As always with these questions it seems to be a religious thing. <S> If you ask 2 people you will have at least 3 different answers and most of them will sound somewhat reasonable. <S> I had the situation that my FIs always taught and asked me to move the planes (taildraggers) with me pulling the plane on the prop and them steering using the rudder. <S> A few days ago another guy walked up to me when I moved the plane shouting at me "NEVER do this, you'll destroy the prop"So <S> I called the technical support of the specific airplane (Diamond Aircraft) and asked them. <S> TL;DR: <S> Manufacturer says that's exactly the way they move the planes in production when they don't have the tow bar around. <S> For reference: The plane has an electric constant speed prop <S> so I guess about the most fragile you can find in terms of prop. <S> Of course you should always grab as close to the spinner as possible <S> One can verify plane specifically this from POH or AMM, for example Diamond DA 62 AMM states: <S> I know this thread is 4 years old <S> but I could not find the questions answered anywhere else and the question comes up on a regular basis esp. <S> in clubs where "knowledge" is passed on from member to member. <A> How do you taxi your plane? <S> I use my engine to spin my propeller, which pulls on the hub and pulls my plane hard enough to make it roll on the ground. <S> On takeoff, I do this so hard that the 2000+ lb plane rolls 60 knots or so before it leaves the ground. <S> Now, with that in mind, do you think pulling on the prop, close to the hub, enough to move the plane 10 feet is doing any damage?
|
Pulling on a prop right beside the hub will cause no harm - that's where the propellor thrust goes anyway.
|
What types of wood can be used for making propellers? Early propellers were made from wood and they still are on some vintage/classic aircraft and reproductions. What types of wood are typically used to make wooden propellers? <Q> Historically , the following woods were used: Mahogany Walnut <S> Oak <S> Almost all wooden propellers are reinforced to add strength. <S> Fabric or metal coverings can be added too. <A> Propellers should be made from the same type of wood as wing spars: In both cases the requirements are the same, and the wood should have the highest strength to mass ratio. <S> Both need to be light and strong, especially in tension in the case of propellers. <S> However, using a hardwood will help with their resistance against nicks and scratches, so for the highest loadings , hickory, maple and oak are good candidates. <S> Spars use softwood like pine or nordic spruce (wood from higher latitudes grows more slowly and has better strength) which are less often used for propellers. <S> Historically a wide variety of materials has been used. <S> Culver Props selects maple for the highest strength and otherwise birch. <S> Mahogany and cherry are selected for the looks. <S> Equally important is the glueing from laminated planks and shaping. <S> The craftsmen at the worlds first propeller company, Chauvière , were first in the business of making toilet seats. <S> Switching to propellers came naturally. <S> Laminating helps to control the density of the wood planks and makes it easier to cut out imperfections, so laminated propellers are better balanced and will be 25% lighter because less allowance has to be made to account for imperfections. <A> Wooden propellers can be made of virtually any wood , I know Sensenich makes theirs of birch, and the company featured on this episode of "How It's Made" apparently uses maple. <S> I would assume that hardwoods (birch, maple, oak, etc.) are favored over something like pine or spruce that would be easily dented in operation if the propeller kicks up rocks on the ground, though I can't find a good reference on that. <A> Wing spar material is usually sitka spruce which is too soft for propellers. <S> I would not sit on a sitka toilet seat either as the slivers from it are toxic.
|
Birch, maple, oak, mahogany or walnut are good choices.
|
What does feathering mean and how does it work technically? Before I ask "What does Feathering mean when it comes to Jet/Propeller Engines" I have to say what I think I know: Feathering jet/prop engines mean achieving a sufficient turbine rotation speed at which, the general functionalities such as VFG drives (elec), pumps, etc. could start operation. I would very much appreciate an explanation with any anomalies. <Q> Feathering is only possible with variable pitch propellers and means that the blades are turned such that their mid-to-outer section is aligned with airflow and they create minimal air resistance. <S> This is done when the engine is shut down and the propeller should create minimal drag. <S> This means also that all accessories on this engine will not be powered anymore. <S> Due to the normal twist of a propeller blade, some sections are still not completely aligned with airflow and produce more normal force and drag than they would if all sections could be aligned with airflow at the same time, but in total those forces will cancel out, and the propeller stops windmilling. <S> This picture of a C-130 engine with feathered prop should help to illustrate the concept. <S> On pure jets no equivalent setting is possible (we have to wait for variable-pitch fans to add this in the future). <A> Feathering is not engine starting, and also is not used in turbine (excluding turboprop) aircraft. <S> In a piston or turbo prop aircraft, in the event of an engine failure, to decrease drag so you can either glide farther or have better performance on the remaining engine(s), you can set the prop pitch lever so instead of facing at a right angle to drive air backwards and produce thrust, the propeller will instead turn edge-first into the airstream, reducing drag. <S> Not all propeller airplanes have this capability, but it's an added safety feature. <S> In motorgliders (both light sport aircraft and primary) without retracting blades, the feathering position turns the prop so that the edge faces into the airstream and also locks the propeller so it no longer turns. <A> This feature is mostly incorporated in Multi Engine TurboProp Aircrafts such that if there is an engine failure (any one of the engine); the propeller blades of that engine are feathered so that they produce the minimum drag and also to prevent the windmilling (a condition where the air flow rotates the propeller and in turn the engine, this is a situation where engine is rotating without lubrication and is a very serious concern). <S> So, when an engine fails the singe acting propeller blades which are fitted with counterweight, have a tendency to rotate toward the high pitch or coarser pitch (toward feather) which is also assisted by a spring inside the pitch change cylinder. <S> If the propeller is a double acting and without counterweight they are usually provided with Manual Feather Pump which works even if the engine is not running and help turn the propeller blade by oil pressure in the cylinder and helps in minimizing the drag or prevent the windmilling condition.
|
Feathering means to align the propeller blades such that the pressure difference between the camber face and back face are almost equal and hence they produce no thrust or drag.
|
What happens to the spinning wheels of the landing gear after takeoff, before retraction? What happens to the spinning landing gear right after V 2 on takeoff? Are they automatically or manually braked to a halt before gear retraction? Or are they allowed to spin to a halt in the wheel wells? I am asking this question in the context of common passenger planes, such as the Boeing 737-800 or the Airbus A320. <Q> In most common passenger aircraft brakes are automatically applied when the gear is retracted. <S> The wheels stop spinning before they enter the wheel well. <S> This is particularly important because a spinning damaged tire may cause damage to hydraulic and fuel lines which are usually routed near the wheel bay. <S> The nose wheels have no brakes, so they are spinning while they are being retracted. <A> The question was formulated in the context of a jet liner such as the Boeing 737-800 or the Airbus, I do not understand why there are persons responding to this question in the context of a smaller less complex aircraft. <S> With that being said, I will like to expand the answer by DeltaLima. <S> Boeing uses a device attached to the Brake Metering Valve Module called a De-spin Actuator. <S> This device directs controlled hydraulic fluid to the brakes when the landing gear lever is set to retract to stop the spinning of the wheels. <S> More information can be found in the AMM ATA 32 (Aircraft Maintenance Manual Chapter on Landing Gear). <S> https://www.facebook.com/aviationisawesome/videos/1598830786833154/ <S> Video of a 737-500 from inside the main gear wheel <S> well shows: <S> After becoming airborne, the landing gear suspension unloads and the wheel hangs down, still spinning Once the main gear arms begin retracting, the wheel stops within a second <S> The gear has fulled retracted in 6-7 seconds. <S> De-Spin Actuator <S> Source: http://www.eaton.com/ecm/groups/public/@pub/@eaton/@aero/documents/content/ct_194202.pdf <A> These are the "nose wheel spin brake linings" (the braking pads) that stop the spinning of the nose wheel after retraction. <A> I fly retracts and have heard this question a dozen times. <S> Some people say to tap the brakes, other people (like me) never do. <S> I have asked certified mechanics, and they have all said it doesn't matter. <S> My advice is to follow the POH. <S> If it says tap the brakes, then do so. <S> Otherwise do or don't it doesn't matter. <A> General policy when operating a retractable gear aircraft is to apply brake pressure after becoming airborne and prior to commanding the retraction of the landing gear. <S> This causes the wheel to cease spinning, removing gyroscopic precession loads on the landing gear during retraction (remember a spinning tire acts like a big gyroscope and wants to maintain its orientation in space) as well as reduces the chances of damaging components inside the wheel well when the gear is stowed. <A> Follow the POH is always the best and most correct answer because it is different on different models and types. <S> I have a 1971 C177RG POH in front of me right now <S> and it says: Landing Gear RetractionBefore retracting the landing gear, the brakes should be applied momentarily to stop wheel rotation <A> On the 737, the main gear gets gear retract braking pressure when the gear lever is placed in the UP position. <S> It also doesn't hurt that a heavy brake stack will close up under gravity as the wheels are turned horizontal during retract. <S> The nose wheels are free to spin up into the wheel well, where they contact a friction brake that drags on the tires; slowing and stopping nose wheel spin.
|
Most aircraft have rubber brake pads (snubbers) fitted in the nose gear bay that stop the spinning of the gear once the wheels are retracted.
|
Can a weather balloon move horizontally? How does a hobby weather balloon control its flight path? Just it just keep rising straight up vertically, always at the mercy of the winds, being swayed side to side? Unlike a rocket/drone, it does not have an engine/motor that can be controlled remotely. So if I want the balloon to hover over a particular area and send me images (a particular section of a forest to watch for wildlife activity), how do I do it? All weather balloons seem to be aimed towards gaining altitude and taking NASA like images, but is there a way to move a balloon horizontally and not just vertically <Q> An ordinary weather balloon cannot maneuver horizontally (unless an external force is applied to it) because it lacks the means to do that. <S> It has only one purpose, to soar up to the altitude where the air pressure inside is more than outside and then burst. <S> If you want it to steer, you can add steering servos ( as mentioned in this PDF ). <S> Of course this will add cost and complexity. <S> There are some websites for Balloon Trajectory Forecast , which might be helpful. <S> Only if Larry Walters had thought about this, things would have been different for him. <A> Yes, I think a balloon can move horizontally the same way a cloud can (by wind). <S> if I want the balloon to hover over a particular area and send me images (a particular section of a forest to watch for wildlife activity), how do I do it? <S> I think I've got a simple answer to this one: Use a rope. <S> At least for a small balloon that's only 1 or 2 hundred feet up you could let it rise up like a kite and tie it off over your desired area. <S> You might even be able to use a security camera wire to enable using a (relatively) cheap security camera, sending power & video up & down the wire, instead of a wireless camera. <S> And you'll have the desirable ability to pull it back down to retrieve camera easily. <S> But, if you're thinking of using a giant weather balloon 1000+ feet in the air, I think that would create a hazard to aviation. <S> [Does anyone know of any regulations or laws if that would be illegal anywhere? <S> Canada/US/Europe?] <A> A weather balloon is almost constantly moving horizontally. <S> The only time it is not moving horizontally is when there is no wind and the balloon has no horizontal momentum (gained from rising through layers with horizontal winds). <S> If you want a platform that is in control of its position, you will need something that can provide its own thrust. <S> A weather balloon is not going work for that application. <S> A weather balloon is also not designed to hover, but to rise until it bursts somewhere around 100,000 ft.
|
You cannot control this horizontal motion and the balloon is at the mercy of the wind.
|
Can fuel sloshing in the tanks cause a stall? Cargo planes secure their load meticulously and if it breaks loose, the result is sometimes catastrophic . However, how do you prevent fuel sloshing inside the tanks and causing the same problems as loose cargo? <Q> There are dividers (baffles) in the fuel tank precisely to stop the sloshing. <S> They are just large plates that will stop the fuel from flowing across. <S> High maneuver jets will use bladder tanks (so no air is in the tank with the fuel) as a way to contain the fuel. <A> The answer is no, but some shifting of the center of gravity (c.g.) <S> due to attitude is unavoidable. <S> Tanks are subdivided so the c.g. shift within a single tank is small. <S> You can notice the sloshing after a landing when the aircraft has come to a complete stop after taxiing: It will gently rock back and forth due to the sloshing in the tanks. <S> It takes up approx. <S> 2% of internal volume. <S> However, in a nose-up attitude the fuel will still collect at the back of the tanks, and again only distributing fuel over several tanks will prevent a significant c.g. shift. <S> Subdividing also helps in spanwise direction to prevent high loads on wing ribs when the aircraft rolls. <S> Remember, an F-16 has a top roll rate of 720°/s, which creates a significant inertial pressure on the wing's tank walls. <A> It would theoretically be possible for sloshing fuel to shift the center of gravity (CG) enough to cause an uncontrollable pitch up, leading to a stall. <S> Designers know this and use various methods to prevent fuel from shifting too much when maneuvering. <S> First of all, the fuel is generally stored close to the CG (at least longitudinally, which is in pitch), mostly in the wings and sometimes in the fuselage between the wings. <S> This is to prevent large changes in the CG as fuel is consumed during the flight. <S> So while fuel certainly is heavy, movement will be close to the CG and affect balance less. <S> As Peter Kämpf notes , roll conditions are important as well, and of course having fuel out in the wings will affect latitudinal stability (but also longitudinal with increasing wing sweep). <S> One way to control this is through the use of baffles (or subdivisions). <S> These limit the amount of area available for the liquid to move between areas, preventing large changes during maneuvers but allowing enough fuel to flow during regular fuel burn, refueling, or tank tranfers. <S> Baffles have the added benefit of providing more structural strength, which is particularly important in aircraft. <S> Wing ribs act as baffles in the wings.
|
Some fighter aircraft use a sponge-like mesh in their tanks which is very effective in breaking up sloshing.
|
How does skydiving flight cause shock cooling? While answering this question ( How can reducing power too quickly on a piston engine damage it? ), barit1 said that: Skydiving planes see a LOT of shock cooling, and they pay for it at overhaul time What exactly happens during a skydiving flight which causes a lot of shock cooling? <Q> Skydiving flights are abusive on engines for a number of reasons, but it's all tied to the fact that these flights are all about getting up to altitude, kicking the jumpers out, and putting the plane back on the ground as fast as possible <S> so you can pick up the next group and do it all again, as many times as possible in a day. <S> While all skydiving descents aren't as dramatic as the video I linked to its not uncommon for skydiving pilots to make a very rapid descent at or near idle power. <S> This causes a more drastic temperature change in the engine (particularly the cylinders, which are not producing as much heat but still have lots of air blowing through the fins). <S> In addition to the potential damage from rapid temperature changes the engine is also spending relatively little time at cruise power (it's either at full throttle climbing or near idle descending), and depending on the operation may be shut down between jumps. <S> This is far from the ideal situation where the engine would run at 60-75% power as long as possible. <A> Because they tend to climb quickly to get to jump altitude (high power, hot engine) then descend very quickly to pick up the next batch of sky divers. <S> Time = money. <S> Close the throttle, point the nose at the landing site. <S> However paul indicates in the comments that he worked at a centre where they took this into account and exercised caution (good airmanship) in how the engine was treated. <A> The aircraft in the referenced video showing a very rapid descent is a King Air (or similar). <S> Turbine aircraft really don't have shock cooling issues - standard procedure is engines to flight idle, props to flat pitch, nose down to Vne. <S> Planes like a Pilatus Porter can descend faster than freefalling jumpers and are often used as extras in films (you need to plan these shots with the pilot). <S> "Shock cooling" by definition is a temperature change faster than the metal can react, leaving you with a cylinder that is hot on one side and cool on the other. <S> As I mentioned elsewhere, this is caused mainly by bad airmanship. <S> My place covered this quite well in training, and we didn't have too many problems. <S> (pop quiz moved to separate question ) <A> Shock cooling is not a problem in reciprocating aircraft engines. <S> In fact, today you almost only hear it mentioned in the context of turbocharged aircraft, and even then to avoid shock cooling of the turbocharger. <S> Another common misconception. <S> http://www.avweb.com/news/pelican/182107-1.html?redirected=1 <A> Having flown skydiving ops in both a C182 and a C208, I can make a few comments. <S> First in the C182, the practice was to descend with cowl flaps closed, the throttle retarded but not at idle. <S> "Clearing" the engine was done, and typically I would use a 50 degree (plus or minus) turn to maintain situational awareness and to increase the induced drag, and descend quickly. <S> In the <S> C-208 the operation was similar, except that power was brought back, and there was no clearing of the engine, as it is meaningless with a turboprop. <S> On both aircraft I would frequently descend with full flaps. <S> I did not use Vne descents, as often the air was not smooth, and the full flap descent at a lower speed offers adequate visibility and a steeper descent than just Vne. <S> The C182 was not turbocharged, and I know of no one in the area who uses a turbocharged recip for skydiving, although I am sure there are people who do elsewhered Also, in the C182 normally there was a few minutes of flight at reduced power (75 or 70%) while ATC was contacted and the jumpmaster got happy with the traffic in the area, and where he was WRT the dropzone. <S> This allowed CHT to drop more gradually.
|
You'll find no mention of shock cooling in the Pilot's Operating Handbook.
|
Can a drone travel beyond the range of its remote control signal? In a hobby drone, is it possible to set up the autopilot so that the drone travels to a distance far beyond the range of the remote control device and then comes back to the starting point? When I see hobbyists flying drones , it seems the drone always hovers within the boundaries of the field. Is it possible for a drone to reach a friend's house on the other side of town and then come back to the start point? <Q> If the controlling software allows it then yes. <S> There's at least one drone available where autonomous flight is possible ; <S> the Vision 2 FAQ says that the drone will continue its "mission" even if you lose the signal to it, although the overall length of the flight path is limited to 5km and the drone will not fly close to airports. <S> Other drones stop and hover or land if they lose the connection to the controller. <S> Whether doing this is actually a good idea (or legal in whichever jurisdiction you want to operate in) or not is a whole other question. <A> In general, unmanned flight control systems operate in one of two main modes: manual control and program . <S> (There are other modes but these are typically specific situations, such as launch/landing sequences, loss of link (aka "return home"), and any other design-specific operating modes as required (see below). <S> To answer your question, if link is lost while the aircraft is in manual operation, a good flight system will automatically go into "return home" mode, where it flies to a pre-programmed GPS coordinate and altitude. <S> Some software will allow you to customize the sequence, such as whether or not to spiral up to altitude before heading to that coordinate. <S> Other software will backtrace the route it took. <S> Aircraft following a pre-programmed route typically change to manual mode upon completion, hoping there's a good ground link at the other end. <S> In military operations, this is known as a "hand-off" where one ground station takes control from another. <S> One Shadow flight I was running lost link immediately after launch. <S> After completing its autolaunch sequence, it went to return home and circled for hours until it ran out of fuel, at which point the engine stalled and the generator (alternator) hiccuped in transition to battery power, causing the flight processor to reboot, at which point we re-acquired link, though too late to do anything about it. <S> The UAV had already noticed its engine wasn't spinning and initiated its ditch sequence, rolling over and popping the chute. <A> From a technical standpoint, as other answers pointed out, it is technically feasible. <S> For instance, universities have attempted a 180 km flight over the Mediterranean sea . <S> However, there are also legal issues involved when flying a drone beyond the range of the remote control device. <S> For instance, in France , even when using an autopilot to control a drone, a safety pilot must stand ready to take control of the drone in case anything happens. <S> The Chicago Convention (1944), article 8 states that No aircraft capable of being flown without a pilot shall be flown without a pilot over the territory of a contracting State without special authorization by that State and in accordance with the terms of such authorization. <S> Each contracting State undertakes to insure that the flight of such aircraft without a pilot in regions open to civil aircraft shall be so controlled as to obviate danger to civil aircraft. <S> In many countries, these special authorizations can take a few months (a little more than three months in the case of the 180 km flight over the Mediterranean sea) to obtain, so hobbyists usually don't bother. <A> Yes, most of the sophisticated consumer drones allow you to pre-program a track into them and can fly totally autonomously. <S> Also, most of even the less expensive drones (FN1) are designed to return back to their starting GPS coordinates if they lose their control signal. <S> Fn1: Less expensive still means around USD 500 or so. <S> Sophisticated drones are USD 1000 and up. <A> It wouldn't even be very difficult to write the code to do it if you had a GPS receiver on board, especially if you also had accelerometers to interpolate position between GPS fixes. <S> For that matter, remote control via a cellular network wouldn't be particularly complicated from a technical implementation perspective (and this would also aid in navigation if you triangulate position from the towers.) <S> Where the problem comes in is legal issues. <S> Specifically, in the U.S., at least, operating such an unmanned aircraft outside the line-of-sight of the operate is illegal unless you have a special license from the FAA, which is generally only granted to federal government agencies or law enforcement/emergency/rescue organizations or to aircraft R&D organizations. <S> According to the FAA : Recreational use of airspace by model aircraft is covered by FAA Advisory Circular 91-57 <S> (PDF) , which generally limits operations for hobby and recreation to below 400 feet, away from airports and air traffic, and within sight of the operator. <A> Federico was right on in his comment in that this is a weak 'answer' and yes, I know better than that. <S> While not answering the body, this question does answer the one in the title. <S> See Man detained outside White House for trying to fly drone , as well as related stories of that day, for an example on what not to do with your UAV... <S> As a synopsis, if I remember the details correctly, a US Federal employee was at a friends house in Washington D.C. <S> and they were playing with the friend's new quad-copter (some might call it a drone). <S> There was much drinking and celebration and the man was flying the quad while quite drunk. <S> He flew it towards the White House and it disappeared. <S> It landed itself on the White House lawn. <S> So, yes, a 'drone' can fly beyond radio range. <A> Furthermore, it can have a "drone call home" subroutine which would cause it to become "autonomous" (it isn't fully autonomous, but it can fly on it own in a straight line).
|
Depends on the programming of the drone - mostly if it contains code for autonomous operations. From a technical perspective, there's nothing preventing it.
|
Is it worth reporting that I saw a green laser being pointed at the aircraft as a passenger? I was on approach to Vienna yesterday evening when I observed two 2-second green laser flashes 5 seconds apart from one of the rear passenger windows of the B737 where I was seated being pointed at the aircraft. I'm wondering if and what I should do since green lasers are dangerous, and I'm convinced the aircraft was being targeted. Should I report this to the relevant authorities? Is it very common or a rare occurrence? The co-pilot didn't seem very bothered about it in any case and he hadn't seen it. Updates: 20th December 2014: Sent an email to the relevant Austrian authorities. Will see if I get a reply. 22nd December 2014: Sent a report to AustroControl as well. 8th June 2015: No reply to date. <Q> In that case I would definitely report the incidence! <S> It doesn't have to be done by police, but you can give the airport authority a call, that way you don't have to make too much of a big deal about it, and still informed the ones that need to know. <S> They can then advise pilots and keep their eyes open for it. <S> If not, then you didn't make a big deal out of it and are not in trouble for wasting time and money. <A> The FAA encourages report s of laser incidents. <S> They focus on ground observers and pilots, but I think a passenger report would be useful too. <S> The Austro Control site does offer reporting forms for various safety purposes, including a "voluntary/simplified" report, which could be a place to start. <S> As with most reports, nothing will probably happen, but it can help in identifying repeat offenders and keeping statistics. <S> Laser incidents are being taken more and more seriously. <S> The FAA asks pilots to immediately report any incidents to ATC, and when applicable ATC is required to provide a caution every five minutes for 20 minutes and include a warning in ATIS for at least 1 hour. <S> Of course, reports immediately after an incident with accurate position information <S> will be the most useful. <A> I would not report it. <S> Most likely the pilots saw it too, and it is their responsibility to report this. <S> What is necessary is to get the report made in close to real time so the authorities can pinpoint the location. <S> Now, hours even days in arrears, your report would not be useful.
|
If there is a attack on the airplanes, it is important that it is being reported before it is too late. So, a call where you could explain what you have seen and give a opinion is your best bet, if they tell you off then hey, you've tried it!
|
Which airliners could survive an EMP pulse? The incredibly bad, postapocalyptic tv series Revolution begins with a mysterious event that causes all electrical systems to fail all over the globe. Even batteries don't work anymore. In the first episode, after the "event" airplanes immediately start falling out of the sky in flat spins. This had me thinking: which airplanes could survive an EMP-type event (FN1) that fries all electronics and renders electrical systems unusable? This means that even RATs would not be a viable choice. Piper cubs and other single-engine planes with purely mechanical linkages could still keep on gliding and land safely. I don't think any large airliner currently flying could make it. Could even a B-17 or DC-10 make it with no powered electrical systems -- just on unpowered hydraulics alone? Bonus question: if they did fall out of the sky, I'm assuming it would be in lawn dart mode and not in flat spins? Footnote 1: While the apocalypse event in Revolution turns out to not be an EMP, you can assume it was something similar for the purpose of this question. <Q> Older airliners use hydraulics and cables attached to the pilot controls. <S> Some RATs power the hydraulics directly as well so <S> limited control is still possible then. <S> The pilots would get a workout but the plane would safely touch down. <S> However planes with entirely fly-by-wire systems (no current airliner is completely fly-by-wire) <S> will be completely uncontrollable apart from shifting weight and would glide to the ground. <S> They are made stable so they won't just enter a spin and pancake into the ground. <A> Simple electric motors may also continue to operate (larger motors tend to be EMP-resistant, in smaller motors <S> there's a chance the EMP could burn out the windings or arc over and destroy the brushes) which means we can assume you'd still be able to pump fuel into the engines of most jet airliners. <S> Thinking along those lines I imagine the remaining DC-3 fleet would be almost entirely unfazed by an EMP (save for any retrofitted avionics, radios, etc. <S> which would likely be fried). <S> Similarly the Boeing 707 would probably not have a problem, nor would early-generation DC-9s, 727s, and 747s - you would lose any retrofitted flight management computers, but they are generally not essential to operation in the earlier-generation aircraft. <S> There are probably several other models still in service (or hanging around various boneyards) which are at least somewhat EMP-resistent. <S> If we assume a Revolution-style apocalypse where absolutely nothing using electricity works you're rather worse off: only aircraft which have cable-driven controls (or hydraulic backups with manual valve actuation & direct pressurization from the ram air turbine) would have functional flight controls. <S> Thats a much smaller subset of the fleet these days, but the planes do exist - as Terry pointed out the 727 and 747 <S> both have non-electric control systems available. <S> If we assume magnetos can still generate a spark the DC-3 other planes of its generation would be the clear winner: The engines would continue to run until stopped (the engine-driven fuel pumps would continue to feed the engine fuel). <S> Aircraft like this could even possibly be restarted (using shotgun starters or pull starters, and a little help getting fuel to the engine until the mechanical fuel pump could take up the job). <S> If we assume magnetos would also stop working then <S> at least you'd have flight controls and the ability to make a controlled emergency landing somewhere as you could in the other planes mentioned. <A> This obviously depends on the distance from origin and strength at source. <S> Aircraft do have some immunity from EMP, they don't just fall from the sky if you make sparks with a 12V car battery 35,000 feet below them. <S> Here's an extract from Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack . <S> EMP simulator HAGII-C testing a Boeing E-4 aircraft. <S> ( Wikipedia ) <S> However if all your navigation and communication systems are fried and ATC is completely dead, your chances of gliding to an essentially uncontrolled nearby airfield and making a good landing must be quite small. <S> Especially at night, in the rain, with a new moon. <A> Having been in the Air Force and worked on bombers and fighters that can carry nuclear weapons all systems avionics and electronics are shielded from EMP. <S> They are not “one time use” and we want them to return. <S> We have divert bases that some may make it to for refuel and rearming Tierra Del Feugo is one such place. <S> Away from strategic baes in the northern hemisphere. <S> Special grounding on the electrical systems for electronics and avionics direct the electrical pulse away from equipment and mechincal devises that have sensors. <S> Normal passenger aircraft do not receive such attention to detail and any communication equipment would be knocked out. <S> However certain types of engines would remain in operation. <S> What would affect our Air Craft the most is the radioactive blast wave if they were static on the Browns. <S> The Enola Gay flew through the EMP and returned to base along with the second camera airplane, though a lot of film on it was ruined. <S> The two aircraft that dropped bombs on Nagasaki also returned to base without incident. <S> Aircraft that dropped test bombs on Bikini Atoll never had any problems returning to base. <S> We have developed weaponary that can deliver an EMP without a nuclear explosion, but what's in the works now are lasers
|
Well the key to an airliner (or any other vehicle) surviving a real EMP would be having engines and flight control systems that don't require any kind of computer assistance. B-52s have been shielded and actually have a lead lined curtain that the pilots pull across the inside of the forward facing cockpit glass. I've read that many modern FBW aircraft (including Airbus and Boeing) still have some fallback manual control of basic flight controls. Hydraulic control systems powered directly by the engine and not relying on a computer to operate the valves would continue to function, as would cable-driven control systems. The answer depends on the strength of the EMP at the aircraft location.
|
Do ANR headsets affect pilots' perception of engine problems? ANR (Active Noise Reduction) headsets reduce the sound level to a pilot's ears by creating an interference wave that cancels out some of the environmental noise in the cabin. Some say that this reduces the pilot's ability to hear minor changes in the engine's sound, thus delaying the point when the pilot would take action to diagnose the problem or land the aircraft. Are there any conditions of engine malfunction or suboptimal performance which a pilot wearing an ANR headset would not be able to detect, but one wearing a passive headset would? <Q> Part 91.205 requires that every aircraft be equipped with the following instrumentation, and these should be the primary mechanism by which engine malfunctions are detected. <S> (4) Tachometer for each engine. <S> (5) <S> Oil pressure gauge for each engine using pressure system. <S> (6) Temperature gauge for each liquid-cooled engine. <S> (7) Oil temperature gauge for each air-cooled engine. <S> (8) Manifold pressure gauge for each altitude engine. <S> (9) Fuel gauge indicating the quantity of fuel in each tank. <S> That being said, ANR headsets attenuate sound, but don't eliminate it entirely. <S> Having flown with an ANR headset for most of my flying career, I can certainly hear variations in engine noise in the mag check and prop exercise during the runup, as well as during throttle and prop changes. <S> I can also hear a fouled plug during runup, as well as verifying it visually on the gauges. <A> In summary, based on FAA/NTSB information it's possible in theory but no one really knows how individual headsets behave <S> and there's no record of ANR headsets contributing to an accident. <S> First, according to a very short FAA information paper on Noise Attenuation Properties of Noise-Canceling Headsets , it's possible that they can mask important sounds: <S> While this technology can have many beneficial effects such as providing clearer communications, reduced pilot fatigue, and added comfort, electronic attenuation of important environmental sounds and alarms may occur <S> But the paper has no specific information or examples, and its only purpose seems to be to encourage operators to do their own testing (which is reasonable, since headsets can be very different): Evaluations should be conducted while both on the ground and in flight during normal operating conditions to ascertain if any audible alarms or other environmental sounds, or combinations thereof, can be detected while electronic noise attenuation is on and active. <S> That paper is from 2007 and a letter of interpretation from the same year on headset requirements in part 121 operations implies that the FAA's main concern with ANR headsets is (or was) that the batteries run out and that might cause problems: <S> The FAA is particularly concerned, however, that Active Noise Reduction (ANR) headsets and headset adapters [...] <S> that rely on battery power are subject to failure <S> when [...] <S> batteries discharge under normal use <S> And the FAA's general brochure on Hearing and Noise in Aviation <S> mentions ANR headsets without any warnings or recommendations. <S> Finally, the NTSB's accident database has only one specific reference to an ANR headset (that I could find) and it explicitly ruled out any effect: <S> On January 5, 1998, the NTSB IIC used a Cessna 208B to determine if the Telex model ANR-4100 active noise reduction headset worn by the pilot at the time of the accident could have eliminated his ability to hear stall or fuel selector warning horns. <S> All aural warnings were clearly audible with the engine operating and the headset active. <S> The information I found online on ANR headsets is overwhelmingly positive and I couldn't find any informal reports of pilots mishearing engine sounds either. <A> When talking about GA, if (for example) one spark plug goes bad, you can actually notice a difference when listening closely, and i doubt you could hear that with ANR! <S> But one spark plug that goes bad during flight is not gonna kill you (well, hopefully anyways!). <S> If there is a problem that will cause major power loss on the engine, you will definitely hear it! <S> Other things like engine roughness, which is primarily as sign for lack of carburetor heat might not be heard though. <S> Yet, when flying with a normal headset I find it hard to hear when the engines sound changes over some time anyways. <S> A ANR headset will reduce, but not limit your ability to hear the engine. <S> It is a lot more comfortable during cruise though.
|
Although its possible to detect engine problems audibly, I don't think that's the primary mechanism (except for engine out) by which pilots are expected to detect engine anomalies.
|
How feasible is it to use Smart Materials on aircraft? Smart or Shape-memory materials have been known for quite long. What factors/limitations are put on it for applications in aircraft? For someone who doesn't know much about its material properties, it seems quite good to have deforming wing or other parts and seem to improve aircraft performance. (One example might be: suitable wing geometry deformation according to aircraft's speed regime) <Q> Shape-memory alloys <S> are only a small part of smart materials. <S> Once deformed, they will change back to their old shape when heated or subjected to strong magnetic fields. <S> Of the many alloys with this characteristic, only a few like nickel-titanium would be suitable for primary structures. <S> Also, heating and cooling would be required to switch between shapes, which is very energy intensive when the outer structure of an aircraft is involved. <S> Airflow will ensure intense convective heat transfer, and to maintain the needed temperature will be very uneconomical. <S> Please consider that an aircraft with shape-memory alloys would need to carry extra fuel for heating or cooling over much of the flight time. <S> Hinges and electric or hydraulic actuators will have a clear mass advantage when you consider the system mass, including energy sources. <S> I guess you agree that creating strong magentical fields in parts of an aircraft is an exceedingly bad idea, so I will rule out magnetic shape-memory alloys . <S> Sure, a smooth shape is aerodynamically better than one with a contour break at the hinge line, but the small aerodynamic advantage of shape-memory structures is quickly lost when you look at the whole picture. <S> Another disadvantage is the accumulation of small cracks with every shape change. <S> In the end, much of what can be said about other smart materials also applies to shape-memory alloys. <S> Their main function is to justify research grants and to keep the press occupied. <A> SMAs are being used by Boeing in so called chevrons, See this link and this image: <S> The idea is that these chevrons heat up due to the hot flow coming from the engine. <S> This causes them to deform, and bend into the oncoming flow. <S> This causes vortices, which will reduce the engine noise by gradually mixing the hot and cold flows coming from the engine. <S> It should be noted that this is a very different application than the one OP mentioned, as it is non-critical and not a stress bearing part, however, it does show that SMA's can be used in commerical aircraft <A> Im not sure this falls under Smart materials but is an interesting side note about shape distortion with heat. <S> The SR-71 stealth plane was subject to such high heat at upper ends of its speed range that the planes panels were actually designed with gaps so that it would not crunch its self to bits when it heated up and expanded. <S> Keeping this in mind you can get an idea of how fast you need to travel to generate enough surface heat to deform the metal substantially <S> (im sure its a bit slower for softer metals). <S> Back to the topic at hand Weight is a serious concern as well. <S> Generating heat or substantially cooling a structure at will is no simple task. <S> Such systems would further weigh down an airplane when weight is really the biggest concern in aviation. <S> Money and well more money is a very real factor in airplane building. <S> FAA type certs are not cheap or easy to come buy and as such commercial aviation tech tends to lag behind what is hot on the market since it takes many years to get an airplane designed, certified and into production. <S> People have been building aluminum airplanes since we had engines powerful enough to make it a reality. <S> Its a light, fairly easy to work with material that has been tried and tested on thousands of airframes flown for millions of hours. <S> We have tooling and shops to make it into what ever we may need. <S> Keep in mind that introducing a new material is not simple. <S> If you would like a current example look at the adoption of carbon fiber which has also been around for some time now and is only just beginning to see use in real commercial aviation on a large scale. <S> Its been used in general aviation for a bit longer since the parts are smaller and a bit simpler to lay up but still more costly than aluminum.
|
The low number of cycles will either require frequent replacement of the shape-memory parts or a very limited structural life of the aircraft. They are extremely expensive to make and to process, so they have never been an economical alternative. Shape-memory alloys will only switch between two shapes, and intermediate shapes are easier to realize with hinges and actuators.
|
Why does Chicago O'Hare have a penalty box? I was reading What information does a pilot have about aircraft operating on an intersecting runway? and noticed this on the map: ( airnav.com ) Why is a "penalty box" marked on the map? What is it? What is it used for? <Q> In addition to what vasin mentioned in his answer , a mechanic from O'Hare mentioned hearing ATC direct aircraft to go there when they weren't ready for takeoff by the time they got to the runway in a comment on the video that prompted the linked question : They [the pilot of the aircraft not yet ready for departure] sheepishly called and told the tower that they'd need another moment or two before takeoff. <S> The controller goes..."Uh <S> .... <S> yeah, <S> no..... <S> cross Runway <S> two-seven left and hold in the penalty box. <S> We'll be in touch." <S> Apparently ATC doesn't like you holding up the line of departing traffic at ORD. <S> As mentioned in the comments, the concept of having a paved area on or near the taxiways for planes to park while waiting to be ready for departure, waiting for a gate, or other similar uses is not unique to O'Hare. <S> Most significantly-sized commercial airports have such areas. <S> The primary thing that is unique about O'Hare's is just that it's named and the name is on the airport diagram. <S> And perhaps also this particular controller's snarky sense of humor. <A> As described by FAA , it seems like it is for holding aircraft when gate is not available: <S> The Penalty Box is located adjacent to the terminal perimeter Taxiway B, east of Concourse C. Arriving aircraft typically use this position to wait for gate clearing . <S> The pad is able to accommodate ADG IV and smaller aircraft (i.e., no heavy jets with the exception of DC-10 and B-767). <S> No aircraft may occupy the Penalty Box during landings on Runway 4L. <A> First, As a frequent flyer from Omaha, NE to Rochester, NY via O'Hare, I have been in the "Penalty box" more times than can be counted on hands and toes. <S> Second, the use of the penalty box has increased since all airlines pad their inflight times with extra time. <S> The reason is simple, it makes them look better when you always arrive early -or- on time if problems are encountered. <S> (expectations are set low, then exceeded.) <S> Early arrivals caused by padded transit times are more likely to wind up waiting for a gate in the penalty box. <S> Third, this is an old layout of O'Hare; if you notice, the current United concourses are not present. <S> Date here is 1981. <S> This is approximately when construction on them was commenced. <S> Furthermore, more runways have been built since. <S> This may be a copy of the airport before modern expansions were begun. <S> The current "penalty box" has moved to where the "Pe" is in the word Penalty box above.
|
A penalty box is simply a holding ramp for planes that currently have no place to be on the ground.
|
Is there any reason to use only UTC standard time in aircraft and not GMT? Why are we not using the GMT time standard in an aircraft? Why is only UTC the standard on-board? <Q> UTC is in principle the same as GMT. <S> But for accurate applications there is a difference: <S> In technical contexts, usage of "GMT" is avoided; the unambiguous terminology "UTC" or "UT1" is preferred. <S> Wikipedia <S> UTC : Is defined by atomic clock with corrections for leap seconds added manually. <S> UT1 : <S> Is defined by the Earth's rotation, hence is more susceptible for change and less easy to calculate than an atomic clock. <S> However the difference between the two is less than one second. <S> It might matter for your $8000 \frac{\text{m}}{\text{s}}$ satellite or for your $300 \frac{\text{m}}{\text{s}}$ aircraft, but otherwise your can consider them equal for informal applications. <A> GMT (Greenwich Mean Time) is a time zone, observed by the UK and Portugal in winter and by Iceland and a number of African countries. <S> UTC <S> (Coordinated Universal Time) is a time standard, defined by an atomic clock. <S> It is kept synchronous with the solar time by adding (or removing) leap seconds. <S> In the GMT time zone, the time is equal to UTC. <S> Before UTC was defined, GMT was the international reference time, called 'Zulu-time'. <A> Because the earth's orbit varies, the value of a GMT second varies. <S> Technological development, especially the advent of computers required the use of a constant second, not a variable second. <S> GPS, for example, requires the use of a constant second, as do all sorts of aviation related equipment. <S> The history of developing a non-varying standard second is involved to say the least, but in the end the time it takes for a Cesium-133 atom to oscillate 9,192,631,770 times was chosen as the definition of a UTC second. <S> Usage of astronomically determined time as the world's standard for technical purposes stopped on January 1, 1972 (as I remember) except for the purpose of updating UTC. <S> Whenever UTC differs from UT1 (the current astronomically determined time) by 0.9 seconds, a leap second is applied to UTC. <S> Thus GMT and UT1 never differ by more than one second. <S> The world's time zones are all assigned a letter. <S> U is the letter assigned to my time zone (UTC-8, in Oregon), Z to the time zone the center of which in the prime meridian at Greenwich (UTC-0).
|
Saying "GMT" often implies either UTC or UT1 when used within informal or casual contexts. Atomic clocks around the world are coordinated to keep UTC.
|
Do some light sport aircraft have clipped wings to lower their cruise speed? Light sport aircraft may have a max airspeed in level flight at MCP of 120kts . I have heard that there are some light sport aircraft that have had their wings clipped in order to have a lower cruise speed. But why do they clip the wings to reduce the cruise speed? Wouldn't that require a higher speed as less lift is produced at the same speed with less wing area? Also, thinking about gliders having a big wing span and fighter jets having a short wing span I can not see why you would clip the wings? What am I missing? <Q> You must have heard wrong. <S> Clipping wings is done to reach higher maximum speed. <S> You mention light sport aircraft, so I assume they have propellers driven by piston engines. <S> This means their power output is constant over speed and the thrust is inverse with speed. <S> To calculate their optimum cruise speed , you can use the venerable Breguet equation which shows that the aircraft has to fly at its optimum L/D for maximum range. <S> At this speed, induced drag equals zero-lift drag, and span helps to cut down the former. <S> Clipping the wing will shift the optimum cruise speed up, not down. <S> With clipped wings the aircraft has less surface area, which will reduce zero-lift drag. <S> This is the drag component which determines maximum speed. <S> Induced drag at a given speed will go up, but it is insignificant at maximum speed, so the aircraft will be able to fly slightly faster. <A> Keep in mind that less wing area means a higher stalling speed, which translates to more runway needed for TO & landing. <S> Climb performance and max. <S> altitude may also be reduced noticeably. <A> Clipping the wings may help a plane meeting the max gross limit of the light sports, but there are also max stall and max cruise speed limitations, which would be adversely affected by clipping the wings, as Peter explains in his answer. <S> A J-3 perhaps?
|
A plane that already has very low stall and cruise speeds, but it pushing the max gross weight might be made to fit the light sport limits by clipping the wings.
|
Do any ejector seat designs include controllable thrusters? Are there any ejector seat designs with built-in thrusters, or boosters, which the pilot can deploy to maneuver himself out of, or away from enemy territory? A use case might be that after the parachute is deployed, the ejected pilot uses the thrusters to change direction or propel himself in a different path. <Q> An escape from enemy territory is not possible with them. <S> They are controlled by a guiding system inside the seat , but not by the pilot. <S> Ejection by itself is stressful enough, controlling the seat would be too much for any pilot. <S> Nevertheless, this is impressive technology. <S> Even when ejected pointing downward at low altitude, the seat will change course and lift the pilot up . <S> The seat featured in the linked video is the Russian Zvezda K-36 , the only ejection seat which meets or exceeds all US Air Force performance demands. <S> To get downed pilots out from enemy territory <S> the armed forces use helicopters. <S> To build such a capacity into the seat would make it impossibly heavy and dangerous - would you like to sit on hundreds of kilos of jet or rocket fuel while being shot at? <S> Just for the chance of flying home after ejection? <S> And how deep are you allowed to fly into enemy territory for the system to work? <S> No, this idea is a dead end. <S> The most promising concept today is to separate the pilot from the airplane , so he sits thousands of miles away while his craft flies deep into enemy territory. <A> No , the small rockets present in an ejection seat are only for <S> zero-zero ejection situations. <S> Although one can do some maneuverability using parachutes but the purpose of parachutes isn't traveling over land, but descending at a survivable speed. <S> The scenario you mentioned is ejection in hostile environments . <S> Fighter pilots are trained for this and they are taught survival skills where they land. <S> There are some psychological aspects of this too. <A> Back when I went through USAF pilot training I remember being told our ejection seats had gyroscopes in the seat which would rotate the seat upright following an ejection. <S> Unable to find a source confirming this now, though. <S> Although a self-righting seat wouldn't be effective against enemy weapons, it might help against mother nature. <S> And it's pretty cool technology. <S> The violence of an ejection is probably a more important threat than a later threat from an enemy (the enemy can't kill a crew member who doesn't survive the ejection). <S> Ejections from unusual attitudes do happen.
|
Yes, modern ejection seats have rocket motors, but they are only for propelling the seat away from the aircraft and upwards, high enough for safe parachute deployment .
|
Is there a legal maximum altitude? In the US, is there a highest legal altitude allowed for certain planes and does it depend on the plane? I heard from a sort-of-reliable source that the maximum is 45,000 feet but I haven't been able to confirm this. I ask since a plane I travelled in very recently was travelling at an altitude of over 55,000 feet and, when it did, turbulence was terrible (some told me I was lucky to be alive). Note : I have tried Googling this and have found no answers. <Q> In some juristictions there are more specific laws, eg <S> It is illegal to operate an unpressurised aircraft above 25,000ft <S> However, each aircraft has a service ceiling when it is certified, and it would be generally illegal to operate the aircraft above this altitude (because it's unsafe). <S> I'm fairly confident that you weren't at 55,000ft. <S> No currently-operating commercial airliner <S> I know of has a service ceiling higher than 45,000ft (the newer -800 version of the 747) and they almost never operate above 41,000ft. <S> A few private jets can go a little higher, up to around 50,000ft, but I know of no non-military/experimental aircraft which is currently capable of going much above 50,000ft, even if you were daft enough to try. <A> Jon Story's answer is correct, but I will add that the cabin displays often have incorrect information on them. <S> I have seen wrong times, wrong locations, impossible flight paths, impossible air speeds, etc. <S> The mere fact they call it an "entertainment system" tells you something. <S> I suspect the altitude may be coming from a cheap, dedicated GPS unit. <S> A lot of GPSs have inaccurate altitudes. <S> Some have a "barometric" sensor-derived altitude which is often wildly incorrect. <A> The max allowed altitude has little to do with jet ability climb over 50k feet. <S> The regulation that determines it is simple: it must be 4 minutes or less it takes the jet to get to 14k feet safely in the event of sudden decompression. <S> Private jets are usually capable of doing that such as the Cessna Citation X rated at 51k feet. <A> In your question you asked if "certain planes" have altitude restrictions and the answer is yes. <S> Very small or light aircraft have altitude restrictions, for example: light-sport aircraft are limited to 10,000ft MSL. <S> As for the rest, I can guarantee you were not at 55,000ft, airliners nowadays have service ceilings (the plane physically can't climb higher, not a law) at 45,000ft max. <S> The Concorde could cruise as high as 60,000 but it stopped flying in the early 2000s, some business jets can go up to around 50,000ft.
|
There's no legal limit of how high you're allowed to fly by law: there's no law that says It is illegal to fly above X,000ft
|
What is the source for the flight data shown on in-flight entertainment systems? This question which claims that an altitude of 55,000 ft. was observed on a passenger's in-flight entertainment system on an Emirates B777 made me wonder: What are the normal sources of information for the flight data displayed on passenger IFE systems? Of particular interest are the common sources for the following information: Altitude (Is this a pressure altitude? Indicated altitude? A GPS-measured altitude? A radio-altimeter-measured absolute altitude?) Speed (This seems to typically be true ground speed, which I'd assume comes from GPS, but any further insight would be appreciated) Latitude/Longitude position (Is this from GPS? INS? radionav? some combination?) Wind speed <Q> I work on these panels which get the data (both IFE and cockpit display panels for a big OEM and there are very few in the world :)). <S> This is all Air data systems which are providing all the data. <S> We get this data from various sensors placed inside the cockpit or on aircraft exterior including wings and tail. <S> For your question Altitude, elevation. <S> azimuth there are some radars in the aircraft which gives that data and some of these radars measure and send this data using CAN protocol with very high speed varying from 40ms to 100ms. <A> After a brief search I found an old US patent that states: <S> The video display system of the aircraft is directed by the present invention to automatically display aircraft ground speed, outside temperature, and altitude, among other information of interest, as sensed by the aircraft's navigation and air data systems. <S> Hence I believe the information comes from same system that the pilots use, though the actual implementation may not be known to any of us outside companies that produce those IFEs. <A> My experience on a 757-200 owned by Icelandair this week was interesting. <S> The Lat/Long DD:MM data displayed on the seat back display was OK for Latitude but wrong for Longitude. <S> The aircraft Track was roughly NNW with a westerly component but showed the following bizarre series of positions: <S> 18:02W <S> 18:01W <S> 19:00W <S> 19:59W <S> 19:58W <S> ........... <S> 19:03W <S> 19:02W <S> 19:01W <S> 20:00W <S> 20:59W <S> etc <S> The degrees increment as expected, while the minutes decrement strangely. <S> Same bug observed on the return trip. <S> The degrees W decrement as expected, while the minutes increment. <S> Clearly this data is not a direct display of raw GPS data, but is being generated by the in-flight software presumably based on GPS input
|
Their are different kind of data transmission buses like ARINC which transmit that data then the required data is fed to IFE system through a protocol but most crucial data like data coming from Weather Radar etc is kept for Pilot usage and is displayed on the cockpit display panels.
|
How fast can fuel be siphoned out if you leave the cap off? It is a dreaded scenario; forgetting to secure the fuel cap. I understand the low pressure area generated above the wing will siphon fuel out of wing tanks, how fast would this happen in a smaller GA airplane with wing tanks (something like the Cherokee perhaps) if the fuel cap was to be completely forgotten (rather than just not tightened)? Also, would it be able to suck the tank completely dry or would there be some limit to the amount of fuel that might be lost this way? I just had X-plane do this to me while doing some IFR practice and it reduced my fuel with about 2 gallons/minute per tank until they were both completely empty and I was wondering if this is realistic. <Q> It can happen very quickly . <S> I don't have exact numbers, but an acquaintance had this happen in a Cessna 172 and the entire tank was emptied in just a few minutes - the amount of time it took to do one circuit of the pattern and land. <S> The fuel cap was not in the filler neck on departure, and was hanging from the chain, banging against the wing. <S> The moral of that story is: never assume the fuelers put the cap back in. <S> I've personally flown an older Cherokee 160 that had a loose fuel tank gasket. <S> Fuel would flow in a rather frightening amount back along the wing, and that's with the cap still on. <A> Looked over my shoulder before the first turn onto crosswind and discovered that the rear windshield was utterly covered in fuel - easily a couple of litres a minute. <S> And that was with the cap firmly in place (the first thing we checked after shutdown!). <S> It was a long time ago, but I think the engineers said it had been sucked out through the flap tracks <S> and we probably had a wingful of fuel vapour. <S> Nice... <A> A friend of mine once flew about 2.5 hours with a friend in a 1975 172M after topping-off and forgetting to cap one of the tanks. <S> The flight included some IFR practice maneuvers- turns, constant-speed climbs and descents, etc. <S> Upon landing and refueling, he discovered, in horror, the uncapped tank. <S> He was surprised to find that he only needed to add about one gallon more than his expected fuel burn should have used up, so if it was siphoning out, it was only a trickle. <S> The chained cap must have been banging against the wing, though, because it left some marks. <S> Fuel starvation is obviously a critical situation, and I'm sure it's not the same in all aircraft, but the 172 did okay with one missing cap.
|
I was once passenger/safety-pilot in a Cessna 150 where the gasket between the tank and the wing skin had failed. When doing slow flight, the pressure above the wing was so strong that it would start to ooze fuel from the cap.
|
Why don't airlines have in-flight video recordings like buses do? That way we could study plane crashes more closely, or terrorist hijackings, or resolve passenger disputes. Even buses in Ecuador have video cameras.(WARNING: shocking video) <Q> Many airlines do in fact have inflight camera feeds for Cabin surveillance <S> so I do not think the question is relevant to most major airlines anymore. <S> These Cabin cameras can be accessed by Cockpit crew through the System Display or the Cabin crew through the FAP (Flight Attendant Panel) and for any abnormal situation such as a hijacking/hostage situation on ground, the CVMS can be accessed on a laptop via the GSP (Ground Service Panel). <S> Additionally, as mentioned above, they have landscape cameras installed for an external video feed but that is more of a feature for passengers. <S> The advantages of a CVMS in a hijacking/hostage situation such as positioning, identity, body language and weapons of the hijackers plus general operational advantages such as issues during boarding/offloading and other emergency situations such as an evacuation are great and not to be discounted. <A> Regarding cabin cameras, there's not much of a need for them. <S> Busses typically don't have flight attendants. <S> In-flight disputes are typically handled well and quickly by the cabin crew on an airliner. <S> Also, theft or assault would have dozens to hundreds of eyewitnesses and no route of escape for the perpetrator, unlike on a bus (which is probably why such incidents are almost completely unheard of on airliners.) <S> It's usually pretty obvious when an airliner has been hijacked, but there's not a lot that people on the ground can do about it, aside from the possibility of shooting it down if it appears to be threatening a 9/11-style attack. <S> Regarding exterior cameras, these are actually starting to appear on some airliners now. <S> Newer airliners like the 777-300ER and the A380, for instance, have them, though I don't think they actually record the video. <S> Even if they did, it seems unlikely that they'd provide any useful information beyond what the FDR data and accident scene examination had already revealed <S> (i.e. they'd basically just show that the plane ran into the ground, which would already be known by the time you found the video.) <S> Regarding cockpit video recording, there is an answer here <S> that addresses it. <S> There have been some suggestions for this to be added over the years, but pilots tend to be against it and the additional information it would provide would likely not be particularly useful in most instances, given that we already have a recording of all of the conversations up to the time limit of the recorder as well as the FDR data. <A> Note that cameras are already installed in some aircraft; but I believe this is an operator option and not standard equipment. <S> For example, from this incident report of a 737-800 PDF: The captain stated that he could see on the cabin observation camera screen in the cockpit that a CCM was wearing personal breathing equipment (PBE). <S> The captain switched off the IFE. <S> This action also switched off the camera since the IFE and the camera are on the same electrical bus. <A> You will see them very soon. <S> Actually, I have already made the software for that :) <S> and we will be delivering to few of the Airlines very soon as I work on those systems where we will have the DVR (Digital Video Recorder) <S> and and a live streaming panel. <S> This recording is only manually controlled just by push of a button by pilot or crew. <S> You will see them in B787s. <S> There are few in A350 also for few airlines.
|
For a specific example, Emirates Airline employs the Cabin Video Monitoring Systems (CVMS) across its fleet of Airbus A380 aircraft. In the case of a terrorist hijacking, having video wouldn't really help much.
|
Why does "no aircraft cross directly over the pole"? This is from the last paragraph here : ... no aircraft crosses directly over the pole – the closest route is 60 nautical miles (nm) away. User Michael Shen of York University asked this originally under the article. <Q> This article from AA (titled "Over the Top" by Gerard J. Arpey) says, By the way, because of the limitations of older navigation systems, none of the polar routes we fly crosses exactly over the North Pole. <S> Fortunately, that is not an issue with the latest generation of long-haul aircraft, such as the Boeing 777s we fly, whose source of navigation is the extremely precise Global Positioning System (GPS). <S> Nonetheless, to make polar flying equally effortless for both the new generation and the previous generations of aircraft, none of the approved civil polar routes comes closer than about 60 nautical miles from the Pole . <A> Until recently, regulators have insisted that twin-engine jets must always be within three hours of a suitable place to land. <S> This is because the failure of one engine on such a plane is potentially far more serious than for one with three or four. <S> However, commercial flights do fly over the North Pole. <S> For example: a number of flights that flies between US and Asia will fly over the North Pole Denver to Delhi <S> It is possible to fly over South Pole as well. <S> In 1977, PanAm 747Sp flew over South Pole while flying from Sydney to Recife. <S> However, South Pole does not lie on the great circle route for too many points. <A> I'd like to augment Chris's answer by noting that the mechanical issue in question is called "gimbal lock". <S> It occurs when a three-axis-of-freedom system, such as a gyroscope or compass suspended in two gimbal rings, gets two rings aligned in the same plane. <S> The aligned rings are now "locked" and cannot detect motion in the plane of the rings. <S> You can imagine the problem by picturing a telescope (or a gun) on an azimuth-and-elevation mount, trying to track an aircraft flying directly overhead. <S> As the plane approaches, the telescope elevates all the way to 90 degrees, but then to follow the plane, it would have to instantaneously spin around 180 degrees in azimuth. <S> A human can easily solve the problem by turning the telesocpe as fast as possible and reacquiring the target on the far side, but an electronic system would have lost the target by the time it finished rotating. <S> Depending on its complexity, it might not even be able to decide which direction to turn in the first place. <S> The same is true of early gyrocompasses flying directly over the pole. <S> Compasses that suffer from this problem are usually designed to shut down when approaching gimbal lock to avoid damage to the mechanisms. <S> The compass would then have to be reset and manually re-aimed to align with the Earth's rotational axis, which would probably have to wait until the aircraft landed. <S> To avoid the possibility entirely, aircraft are advised to give the pole a wide berth, even though modern gyrocompasses do not suffer from this problem. <S> That's not to say no aircraft has ever flown over the poles. <S> Admiral Richard Byrd famously made multiple flights over both the North and South poles, and there's no reason a gyrocompass couldn't be designed with polar travel in mind. <S> (It would risk gimbal lock somewhere else on the planet instead.)
|
At the Pole, an airplane’s compass changes from a due-north heading to due south, and that change of course could potentially lead to problems with earlier-generation autopilot systems.
|
How does an airliner deal with cabin altitude at an airport above 8000 ft? There are a number of airports above 8000 ft altitude . FAR 25.841 states: Pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet at the maximum operating altitude How does an airliner operating from a high airport, say from El Dorado , deal with cabin pressure? Do they actually pressurize the cabin after takeoff and depressurize it after landing? Note: the answer can be of any jurisdiction though FAA seems relevant here as US airlines operate from there. <Q> Here is the text extracted from Boeing's 777 Flight Crew Operations Manual: <S> In cabin altitude controller cruise mode, maximum cabin altitude is 8,000 feet. <S> When the takeoff field elevation is higher than 8,000 feet, the cabin descends to the cabin cruise altitude while the airplane is climbing . <S> When the destination airport elevation is greater than 8,000 feet, cabin altitude controller cruise mode maintains a cabin altitude of 8,000 feet . <S> (...) <S> At touchdown, the outflow valves open to depressurize the cabin. <S> Therefore, when the airplane is on the ground, its cabin altitude is always equal to the ambient altitude. <S> When it is in the air, the maximum is 8000 feet. <S> Whether the cabin altitude will climb to 8000 feet or descend to 8000 feet depends on field elevation. <S> The reverse happens upon landing. <S> If landing at an airport at 10,400 feet, the cabin altitude is <= <S> 8000 feet until touchdown, then raises to 10,400 feet. <S> This make sense - if the outside pressure is greater, how do you open the door? <S> (well with enough force you can, <S> but I will leave it to your imagination as to what happens the moment the door is opened). <A> I am an aerospace engineer, who has worked on the design and certification of pressurized aircraft, so let me try and answer. <S> The class of regulations that deals with the certification of pressurized aircraft are called 14 CFR 23.841 (General Aviation) and 14 CFR 25.841 (Commercial). <S> Both paragraphs are pretty much identical and in summary <S> say the following (paraphrasing): <S> All GA and commercial aircraft designed and certified to cruise at altitudes <S> greater than 25000 ft must be pressurized. <S> This means that aircraft whose maximum altitude (often referred to as "service ceiling") is less than 25000 feet do not have to be pressurized (once you exceed 14000 feet, most people begin to use supplemental oxygen, but above 25000 feet your plane must be pressurized and that's what provides your supplemental oxygen). <S> Unpressurized GA aircraft routinely operate at altitudes up to 25000 feet. <S> This should answer what pressurization an airliner must provide at high-altitude airports: None! <S> Not unless said airport was above 25000 feet would some pressurization be required (a problem that does not exist on this planet). <S> What paragraphs 23.841 and 25.841 are saying is that those airplanes that are pressurized, must be capable of providing cabin altitude of no more than 8000 feet at their operating altitudes. <S> So consider two aircraft, one operating at 25001 ft and the other at 45000 ft. <S> Both must provide no less than 8000 feet in the cabin. <S> It shouldn't come as a surprise that the one operating at 45000 ft will require a stouter (i.e. stronger and thus heavier) fuselage as the pressure difference between the cabin and outside is much greater. <S> Many modern commercial airliners provide a 5000 feet cabin altitude and some bizjet manufacturers are already considering sea-level pressure in the cabin, but I digress. <S> Anyway, I hope this sheds some light on this mystery. <S> Cheers. <A> The verbiage of the CFR is important (imagine that). <S> The part you quote is really saying the following: if you want to fly an airplane which is equipped with a pressurization system, then, when the airplane is at its maximum operating altitude, the system must be able to keep the cabin pressure at or below 8,000 feet. <S> Nowhere in the reg you quoted is there anything about maintaining 8,000 feet, and in fact upon landing the dump valves will open and the cabin will depressurize to whatever the ambient pressure is anyway. <S> The aircraft will maintain 8000 feet until touchdown and then depressurize. <S> Thanks @Kevin! <A> In the PC-12, there is a cabin pressurization controller knob (the lower right-hand knob in the image) <S> that allows you to set the actual altitude at which you are taking off at/climbing or descending to/landing at. <S> Let's say you file for FL220. <S> Before departure, you set the cabin altitude on the dial to 22,000 ft. <S> As the airplane climbs, the engine bleed air pressurizes the cabin until the maximum pressurization differential is reached (shown on the PSI DIFF gauge). <S> The cabin climb rate is shown on the dial in the lower left corner. <S> When you descend to land, you set the knob to the destination field elevation + 500ft (the lower internal pressure is so you don't blow open the door!) <S> If the cabin pressure is 5,000 ft, and you're landing at a field that's 8,000 ft, the cabin will climb even as the aircraft descends. <S> If there is a failure of the pressurization computer, the pilot can adjust the cabin pressure manually using the knob in the upper righthand corner. <S> It's fairly simple to operate. <A> I've been waiting for an answer, but none forthcoming - so - this is GUESSWORK :) <S> The cabin altitude cannot be anything except the ambient altitude when the doors are opened before takeoff and after landing. <S> For landing, the cabin altitude would therefore be set to the airport altitude. <S> It cannot be anything else since there are valves which automatically prevent negative internal pressure. <S> For takeoff, my guess is that the cabin altitude would be set to normal according to SOPs for the aircraft and type of flight. <S> If the departure field was at a higher altitude, then this would result in an increase in cabin pressure. <S> Otherwise, the normal reduction in pressure would take place.
|
I imagine that airline crews would pressurize for passenger comfort until descent, and then gradually bleed away cabin pressure until touchdown.
|
Why are passenger seats not facing backward on an airplane? In the event of a crash, facing backward sounds much safer: Forces are applied on a much larger surface (your whole back is in contact with the seats, instead of just a seatbelt and maybe the opposite seat) Most passenger are already in position in case of an unpredicted crash. Passenger without a seatbelt might have higher survival rate Flying objects would maybe be more dangerous, but What made designers do it this way ? Is there any plane with such a configuration ? <Q> You are absolutely correct, backward facing seats are safer . <S> But tradition and a subjective feeling of being treated better means that people will prefer to be seated facing forward. <S> Some even claim that they develop motion sickness when sitting backwards. <S> This can indeed be the case for some people in trains with their big windows, but much less so in aircraft. <S> Just note which seats will be occupied last in a train with lounge/mixed seating. <S> In order to cram the highest number of passengers into their planes, the airlines would need to convert all seats to the backward orientation, and you can be sure there will be some passengers who will complain. <S> If passenger safety would be important to them, airlines could already use better seatbelts, like the 5-point-harnesses used in gliders and aerobatics planes, but they all use the minimum lap belt which is mandated and nothing more. <S> Convenience and cost always win over safety. <S> Now I need to mention two caveats: If passengers should be seated backwards, the industry needs to develop new seats. <S> It will not be helpful to turn existing seats around - they would collapse at much lower loads than what a backward-sitting human can sustain. <S> However, to fully support these higher loads, seats will be more heavy and possibly even the floor structure needs to be beefed up. <S> If the plane flies into a mountain or ditches and sinks before people get out, the better seating will not help. <S> Some military transports have backward-facing seats. <S> In some crashes, the survivability rate was seven times higher in those than in forward-facing seats. <S> Early air travel also used mixed seating, e.g. on the Zeppelins or the Dornier Do-X . <S> One airline to use mixed seating was Southwest Airlines with their "love seats" , and business jets have mixed seating as standard. <S> Thanks to @reirab for pointing out that United Business class also has some backward-facing seats. <S> Cabin of the Do-X. <S> No seatbelts, seats not bolted to the floor. <S> These were the days ... <S> Cabin of the Dassault Falcon 7X business jet. <A> However, some airlines offer backward seat porducts in business and first class <S> For example: United B747 & B777 Business class Etihad A380 business and first class <S> Morover, All(4) types of widebodies in BA do offer Business backward seats , its whole subsidiary Openskies also offer business backward seats in their b757 <A> This is actually somewhat common on GA aircraft. <S> The Beech Bonanza and Piper Saratoga, Meridian, Matrix, and Seneca have "Club Seating" (as well as <S> I'm sure <S> other 6 place planes I don't know about) <S> As seen here in this Saratoga <S> I don't know if this is a safety thing or a design matter <S> but it does fall under your question <S> Is there any plane with such a configuration? <A> I think one more reason is the pitch of the aircraft during climb and descent phases, and the take off acceleration. <S> During take-off and early climb, as acceleration (almost 0.3g for an A320) slams the passenger into the seat back, it would be very uncomfortable to seat backward with only a belt retaining the pax (a 80kg passenger will be subjected to a force of 240N, which corresponds to the load of 24 bottles of water, distributed on all the back in one case, and only the surface of the belt with a backward seat). <S> Moreover the pitch during initial climb can reach 16° (A320) and remains between 10 and 5° during all climb phase. <S> It is oubvious that sitting forward is better (I mean, more comfortable) in those conditions. <S> During descent and landing, pitch is not less than -3 <S> ° <S> (A320). <S> Regarding images with lounge in cabin, I dont know if passengers have to go back to their seat during take-off and landing, for safety reasons. <A> The VC-10s used by the RAF had all the seats facing backward .
|
It seems that backwarding seat make passenger feel not good. Backward-facing seating will only help in the fraction of cases where deceleration loads are too high for a forward-facing person, but low enough to make the crash survivable.
|
Is there a difference between how commercial jets and GA aircraft use airways? In the answer to this question about why people use airways, one of the commentors pointed out that GA aircraft often use airways in a different fashion than commercial aircraft. I couldn't tell from context why this is true though. Is it laziness, spite, lack of knowledge? Or is it simply that GA aircraft are instructed to use them differently? Or, even, is it that GA aircraft are typically at a lower altitude so they simply have different airways? Why do GA aircraft use airways different than large commercial planes? <Q> Below the routing for PC12 operating IFR at FL150 and an A320 operating at FL250. <S> (FPL-DEXAM-IG-PC12/M-SDE1FGHIJ1RWXY <S> /LB1-EDDL1000-N0160F150 KUMIK <S> L603 KOSEK Z74 HAREM <S> T104 ANORA- <S> EDDM0150 EDQT-PBN/A1) <S> The above flightplan from EDDL to EDDM validates for FL240, but anything above FL245 will not pass, it will error out with: PROF195: <S> KUMIK L603 KOSEK DOES NOT EXIST IN FL <S> RANGE F245.. <S> F999PROF195: <S> KOSEK Z74 HAREM DOES NOT EXIST IN FL <S> RANGE F245.. <S> F999PROF197: <S> RS: <S> EDUUFFM14 EDUUFUL13 EDUUNTM13 EDUUTGO13 EDUUSLN13 <S> EDUUWUR14:F245.. <S> F255 IS CLOSED FOR CRUISING REF:[EUROED41A] <S> ED AIP(ENR3.3 1 NOTE 9) <S> To fly the same flight in higher levels, you would need another routing: (FPL-DAXAM-IG-A320/M-SDE1FGHIJ1RWXY/LB1-EDDL1000-N0260F270 DODEN Y853 BOMBI T104 <S> ANORA-EDDM0150 EDQT-PBN/A1) <S> This routing works fine for anything above FL245, below it would again error out with: PROF195: <S> BOMBI T104 HAREM DOES NOT EXIST IN FL RANGE F000.. <S> F245PROF204: <S> RS: TRAFFIC <S> VIA DODEN Y853 BOMBI IS ON FORBIDDEN ROUTE REF:[ED2318A] <S> Y853 DODEN BOMBIPROF205: <S> RS: <S> TRAFFIC VIA <S> DODEN Y853 BOMBI: <S> F000..F245 IS OFF MANDATORY ROUTE REF:[ED2318B] <S> Y853 DODEN BOMBIROUTE135: <S> THE SID LIMIT IS EXCEEDED FOR AERODROME EDDL [EDDL50120A] CONNECTING TO DODEN <A> It depends on the type of aircraft, and the operational support behind the airplane. <S> In the Western US (as I would expect is also true for Les Alpes ), the terrain is quite high, and there is sparse radio coverage at lower obstacle-clearing altitudes. <S> Lighter aircraft will opt for Federal Airways, which have a Minimum Enroute Altitude that ensures obstacle clearance, and radio navigation aid and voice communications coverage. <S> Carriers have huge flight operations departments, which plan the routes taken by their aircraft. <S> Since carriers have scores of flights in the air, they are constantly adjusting routes for traffic and weather, and may file routes that a smaller operator wouldn't consider For smaller operations, there are "Preferred IFR Routes" published in the A/FD (see below). <S> They can also obtain one-off or subscription flight operations from companies like Jeppesen , which give them the resources of a large flight operations department. <A> There are variations in how particular airways are used, but there are not routes that are restricted based on the type of operation here in the US, or anywhere that I know of. <S> As others have pointed out, there may be various restrictions on an airway (route) such as altitude, times of use, directions of use, etc. <S> but they apply the same to GA aircraft as a commercial aircraft. <S> Keep in mind that GA encompasses a wide variety of different types of aircraft, including aircraft that have far less and far more capabilities than commercial aircraft. <S> Saying that a particular airway is restricted to aircraft flying above 18,000 feet does not restrict it to commercial aircraft, and the entire system is based on a first come first serve concept. <A> GA encompasses a huge range of aircraft operations, some of which look a lot like airlines and some which don't. <S> For instance, a student at a flight school is very different from a private jet. <S> That said, most GA operations are VFR in small, low, slow planes. <S> While it varies by country, VFR aircraft are generally not required to file a flight plan nor, in most airspace, even talk to ATC. <S> You can just get in your plane, take off, and for the most part, simply fly wherever you feel like, whether that is sightseeing around town or crossing the country. <S> Similarly, even if you do talk to ATC, it is a lot easier for ATC to keep planes separated if they're moving at 100kt rather than 500kt. <S> So, they don't need much ability to predict where you're going because they have time to just watch and see. <S> Also, small aircraft have a much wider range of performance and mission profiles, from training to crop-dusting to pipeline patrol to cross-country flights spread across thousands of small airports, whereas jets are generally all trying to fly at the same optimal altitude for as long as possible between a handful of medium to large airports. <S> All of these factors combine to result in airline (and to a lesser extent charter jet) operations end up needing a lot more work to keep them from bumping into each other. <S> Airways (and things like SIDs and STARs) help ATC manage that complexity. <A> "GA aircraft" covers a lot of ground. <S> A private pilot out on a VFR cross-country cruise would typically elect to not use airways at all, at least in the US. <S> Why go where the other traffic is concentrated? <A> Commercial and GA often do use different airways near their respective airports, but when at cruising altitude, you may find GA and small turboprop flying on the same airway, at the same altitude. <S> For example, a small regional Q400 flying from Toronto to Ottawa might be assigned at FL220, and since most GA aircraft are capable of that, it is possible that they can be flying on the same airway, at the same altitude. <S> However, it is a different case when they are near their respective airports. <S> Some GA airports close to large commercial airports <S> have height restrictions and the GA planes are made to follow different airways because of wake turbulence, airway congestion, etc. <S> But lots of times, you can also find GA planes at big airports! <S> For example, Vancouver Intl. has a 2 main runways, and another shorter one for small GA planes. <S> So basically, GA planes can have different airways, but it depends on the location, altitude, noise abatement procedures, radar capability, airport size, airspace capacity, and many other factors.
|
In Europe, some airways are only available in certain flight level ranges, so a commercial airliner and a GA turbo-prop travelling from the same departure airport to the same destination airport could be travelling on different routes due to airway restrictions in place and the inability of one aircraft to climb to the same level as the other.
|
Who should handle an emergency when there's both a certificated pilot and a CFI on board? While practicing for my commercial certificate in a T-tail Piper Arrow IV , I put the gear down on downwind, and one green light didn't come on. In the right seat was a CFII/Multi, who had over 1,000 hours but less than 10 hours in Pipers, whereas I had about 300 hours, and over 200 in Pipers, having done my PPL in stiff-legged Cherokees. As a certificated pilot, I was PIC, but we talked about how to handle the emergency, and the CFI and I decided that since I had so much more experience in Pipers, I would handle the emergency tasks, while he handled the radios and looked for traffic. We did the proverbial tower fly by (although they wouldn't say anything except the gear "appeared to be down"), and they cleared me to land on any runway. Our landing was uneventful, and it turned out to be an electrical MX issue. When we landed, however, the flight school nearly fired the CFI for not having taken control of the aircraft during the emergency. Did we make the right decision for me to handle the emergency? Or should I have let the CFI/CFII/MEI with over 1,000 take over as PIC and handle the airplane? <Q> From a safety perspective <S> This is exactly what you did in the scenario you describe. <S> In terms of who calls the shots (acts as PIC for the emergency), generally the most qualified pilot onboard should be the one giving the orders. <S> Deciding who that is falls to the pilots onboard (because they're the ones who will arrive at the scene of any resulting accident first). <S> So in my mind the question really is <S> "How do I determine who is most qualified?" <S> -- Any opinion we can give here comes dangerously close to second-guessing your emergency actions <S> which is something I personally try to avoid, but I'm going to embellish your scenario above for illustrative purposes: <S> The Instructor Former air force pilot ATP, CFI/CFII, MEI. <S> 10,000 hours in various jets, 10 hours in an Arrow (doing this instructing gig.) <S> and for the sake of argument no other time in PA-28s. <S> You PPL + Instrument Rating, working on your Commercial. <S> 300 hours, 200 in fixed-gear PA-28s and let's say 20 in Arrows. <S> I'll further assume you both kept your cool and didn't panic (because if either of you turned into a quivering blob that would automatically disqualify them from taking control of the aircraft). <S> If we go by the certificates, your instructor is certainly "more qualified" - and in 10,000 hours they've probably dealt with more real-world emergencies than you have. <S> If we go by "time in type" and experience flying PA-28 variants you're clearly more familiar with the general type, and possibly this specific aircraft & systems (like the emergency gear extension system). <S> Given the above, having you handle the controls seems to be the most logical course of action. <S> The CFI can do "everything else" - communication, traffic scan, calling out checklists & altitudes, etc. - to ensure that you can concentrate on flying the plane and landing as safely as possible. <A> I don't see a mistake on the part of the CFI. <S> After all, you were in the left seat and legally cleared to fly the aircraft, so it is up to you to decide. <S> By clearly communicating and sharing the workload you did the right thing. <S> I guess the reason why the CFI got in trouble had more to do with insurance issues than with regulations. <S> You don't mention it, but I assume the CFI was employed by the owner of the aircraft. <S> It would be easier for the owner to settle with the insurance company if one of his employees is PIC in an emergency. <A> The instructor did the right thing by letting you fly. <S> I have 1200 hrs on the 737-300, 120 hrs 737-200, approx. <S> 150 hours on the C172 and 80 hours approx Seneca (both a while ago), and a fATPL. <S> If I were in the Cockpit with somebody with more familiarity of the a/c characteristics I'd do Radio and assist as well, leaving them as PIC. <S> There is no time for an ego here. <A> Yes. <S> As you specify it. <S> This sounds perfectly correct. <S> To get the technicalities straight: Who is PF? <S> When you do your departure briefing, you specify who is PF. <S> I was trained to start departure briefing with "I fly Piper Arrow, normal take-off. <S> Maximum power, flaps 10, etc..." and then going on the emergency part, "... <S> I will take all emergency actions, ..." <S> Who is PIC? <S> This is answered by the column in which your enter the hours in your logbook. <S> As PIC, you are in command of the aircraft. <S> You fly it or decide to hand over the flying duties. <S> The instructor can do everything else, checklists, watch your airspeed/altitude etc. <S> However having many more hours than you he is aware of how to fly "an aircraft" better than you. <S> So he can clearly detect if you are not going to be able to finish the job and should (if he feels the need) say "I have control". <S> Furthermore, even if the instructor had experience of landing with a wheel not locked, he may consider it good experience for you to land it anyway - provided <S> you discussed how you were going to do it (airspeed, attitude, rudder (nose wheel), <S> ailerons etc.) <A> As a CFI, whether I was giving instruction to a student pilot or in a jet, I would always give the same briefing concerning who would be in what role during an emergency. <S> The briefing would discuss numerous scenarios, but specifically address who will be the PF given their experience, recency, and time in type. <S> This would always change from pilot to pilot and may change as the student gained time and experience. <S> It's always a good idea to have a plan of action discussed well ahead of any departure. <S> A good example is the Miracle on the Hudson : Jeff Skilling was the PF and Sully was the PM when they departed. <S> It was briefed that in the event of an emergency, Sully would handle the radios and fly the aircraft while Jeff would ran the emergency checklist, so as soon as they loss thrust Jeff transferred controls over to Sully <S> and we all saw what happens when preparation and luck come together at a point in time.
|
both pilots should be handling any emergency that arises, each working to their individual strengths and expertise to ensure a safe outcome.
|
Why doesn't frost form on a moving airplane? When I was a young student pilot, long before the FAA prohibition on polished frost went into effect, an instructor left a six-inch square of frost on the wing to demonstrate how fast it would disappear after takeoff. Sure enough, we hadn't even reached pattern altitude and the frost was completely gone. Furthermore, in my experience frost never forms on an airplane as long as it's moving, or as long as there's sufficient airflow moving across it. I've never been able to find a satisfactory explanation for this. Why doesn't frost form on a moving airplane? <Q> Frost can be formed in two ways. <S> On a colder object by water directly desublimating on its surface or on any object when air is saturated with water. <S> Frost <S> can form on a moving airplane, but only the second way . <S> Why would they have anti-ice on pitot tubes, propeller and leading edges otherwise? <S> If the air is moving it carries away the sublimated vapour and thus increases the sublimation rate. <S> When flying in visual meteorological conditions, that's generally the case, so frost won't form in VMC, <S> thogh watch out when dew point is close to temperature; in such case light haze may form that already causes some icing while visibility is still above the VMC limit. <S> Ram and friction heating also help sublimating the ice a bit. <S> However when you fly into a cloud in freezing temperature, the water droplets will freeze on the aircraft when they hit it. <S> They will hit it on forward-facing surfaces: wing and stabilizer leading edges, propellers, engine inlets, pitot tubes and nose and windscreen. <S> That's why these components have anti-ice, either using heating or deicing boots. <S> VMC-only aircraft will often only have pitot tube heating and carburettor heating, because those can sometimes gather frost in sufficiently moist air that is not yet forming cloud. <S> This lack of anti-ice makes flying into IMC even more dangerous in winter than it already is for all the other reasons. <S> Icing only happens when the cloud contains supercooled water droplets, which occurs in clouds where the ambient air temperature is between freezing point (0°C/32°F) and around -40°C/-40 <S> °F when the droplets freeze to ice pellets. <S> The exact point the droplets freeze varies somewhat because it depends on other parameters like amount of dust, but pilots can check whether they are accreting any ice by looking in the corners of the windscreen. <S> Whether freezing conditions are to be expected will also be mentioned in the detailed weather forecast. <A> Frost does form if you fly into cloud with the correct temperature and moisture levels as explained elsewhere. <S> It can bring planes down if not protected by anti ice systems or where such systems are not used correctly. <S> Secondly, be wary of taking off with frost on your aircraft. <S> It could have unknown effects on the stall speed and aerodynamic qualities of your aircraft (in other words it might not fly). <S> For example if you have frost on one wing only, or the tail, the outcome might be very bad. <S> Finally, faster aircraft such as jets have higher skin temperatures on the leading edges due to friction from the speed. <S> They still need anti icing systems though. <S> Taking to extremes the Lockheed SR-71 Blackbird had skin temperatures of 200 degrees C + when flying at Mach 3. <S> It would also be above most of the clouds that could form ice at that point (not sure of the situation though when it was at 30,000 feet refuelling). <A> A parked aircraft on a still, clear night radiates its heat into the dark sky and becomes colder than the surrounding air. <S> If it drops below the dew point, dew forms; if it drops below that and freezing, frost forms.
|
In flight, the high speed air flow over the aircraft keeps its skin at essentially the same temperature as the air so it doesn't drop in temperature the same way. When the air is not saturated with water, ice will sublimate.
|
What's the right way to take a dog in a small plane? I would like to take my friend and his dog for a flight. What's the safest way to take the dog? and what's a good way to protect the dog's hearing? <Q> My wife and I have a small dog that frequently travels with us. <S> We place her in a soft-sided kennel that straps onto the seat belt. <S> While this doesn't do anything to help in a sudden impact (i.e. crash), it does help to keep her from being bumped around in case of turbulence. <S> For larger dogs, I know that there are seat belt tethers out there. <S> My suggestion would be to strap them to a rear seat. <S> In either case, the big issue is to ensure they don't get in the way while operating the aircraft. <S> Their website is here . <S> My wife and I bought a pair, but our dog wouldn't have anything to do with them and they were returned. <S> Of course, your dog may be better behaved :D <A> When you are flying with pets, there are certain things you need to consider which aren't normally considered when flying with people. <S> Depending on the size and weight of a pet, a suitable carrier in which they can fit in is needed. <S> You also need to make sure that this carrier must be able to fit in the plane and be secured. <S> It should be an approved car safety transport harness. <S> Some general guidelines are: <S> The pet should be secured. <S> Allow the animals to relieve themselves before being loaded. <S> As soon as the trip is complete provide water and some nutrition for the animals. <S> It is very important to always clear the seats and plane after the journey. <S> Dogs are very susceptible to parvovirus . <S> Animals do not know that swallowing and yawning will help their ears in altitude changes like the humans. <S> Hence, it is better the minimize the rate of climbs and descents to minimize discomfort to animals. <S> AOPA has an excellent and detailed article about flying with pets. <S> For the hearing issue, they state: ... <S> [by putting cotton in ears, it can] stuck in the wax of the ears and cause problems. <S> The better option is to use pillow foam instead of cotton. <S> Pillow foam is similar to what earplugs are made out of and is not as likely to get stuck in the ears. <S> I hope that your journey won't go like this: image source <A> My dog flies with his Mutt Muffs . <S> In a pinch, you can also put cotton balls in a dogs ears. <S> Carefully put them in enough that he cannot paw them out, but not so far as to get into the sensitive parts.
|
If the pet is large and cannot fit in carrier which can in the plane, a pet harness that can be secured to seat belts or seat belt attachment points can also be considered. As for the hearing part, a company called Safe and Sound Pets makes a product called Mutt Muffs .
|
Why are movable rocket thrusters not used in airplanes? If an engine fails in a passenger airplane, why can't it have movable rocket thrusters in the wings to help safely land the airplane? <Q> Any time the question is "why don't we have..." , the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, & utility. <S> If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive. <S> Putting rocket thrusters on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board. <S> All that extra weight has to be flown around, requiring fuel. <S> They would need regular maintenance checks, which is another cost. <S> And they would only be useful very, very infrequently (on most planes... never). <S> So, safety issues completely aside <S> *, it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning. <S> This same line of reasoning goes for "why don't more airplanes have parachutes" , "why don't planes have anti-missile systems" , "why don't planes have airbags" , and many other random items. <S> *Safety issues are a big deal with rockets. <S> Rockets are a controlled explosion . <S> What happens if that explosion is not controlled? <S> What happens if the rockets are triggered by accident, or blow up all at once? <S> Even if rockets passed all the tests of utility vs. costs, they would still increase risks to the plane, rather than decreasing it. <A> "Movable rocket thrusters," regardless of propulsion, are used for thrust vectoring , AKA maneuvering , not forward motion. <S> If you're talking about something like an emergency JATO rocket, then the reason is because very, very few accidents happen strictly because of engine failure. <S> Most engine failures (notwithstanding US Airways Flight 1549 ) happen at an altitude where the plane can pick a safe landing spot, and glide to the runway. <A> This is not a factor for commercial airliners, but some research aircraft designed for very high altitude operation, such as the North American X15 have used fixed rocket thrusters in addition to the conventional movable wing and tail surfaces. <S> The use of such a system in a commercial aircraft would in itself pose major safety issues, because of the highly reactive nature of the propellants used in these systems, such as concentrated hydrogen peroxide (HTP). <A> The Boeing 727 was certified with a rocket-assist system as an available option, in order to meet one-engine-inoperative climb gradient requirements for operation at extremely hot/high airports. <S> It was only ever selected for purchase by Mexicana airlines, and was delivered on 12 aircraft. <S> You can find videos of it being tested on Youtube.
|
The advantage of rocket thrusters over conventional aerodynamic control surfaces is that they work in space.
|
Flying out from an uncontrolled field, should I contact approach or departure at the nearby control field? I am a new pilot who flies out of an uncontrolled field. When I depart and want to ask the controller for the nearby controlled airfield for flight following, should I contact approach or departure, or it does not matter? <Q> Approach and departure are two facets of the same facility, the TRACON , and it doesn't matter which you call, unless you're an IFR aircraft on an active flight plan or you have a flight plan on file that you want to activate. <S> For example, at Hollister , the TRACON is called "Norcal," and it handles dozens of different sectors, each with its own frequency. <S> The frequency for approach and departure at Hollister are identical because that frequency is the arrivals frequency for San Jose International Airport (SJC). <S> That's because Hollister is underneath the approach path for SJC, and that's whose radar screen you will pop up on. <S> What you should do is look up the frequency for your airport (or for a nearby airport) in the A/FD, in Airnav.com, or in your GPS database, and use that. <S> If it has a discrete departure frequency, then you should probably use that, even though its for IFR departures, but for VFR, it doesn't really matter. <A> I believe that Approach is the correct phraseology. <S> First, have a look at these definitions from the Pilot/Controller Glossary (my emphasis): APPROACH CONTROL SERVICE- Air traffic control service provided by an approach control facility for arriving and departing VFR/IFR aircraft <S> and, on occasion, en route aircraft . <S> DEPARTURE CONTROL- <S> A function of an approach control facility providing air traffic control service for departing IFR and, under certain conditions, VFR aircraft. <S> The AIM 5-2-7 also says that Departure Control is for departing aircraft only: <S> Departure Control is an approach control function responsible for ensuring separation between departures. <S> So according to the FAA's definitions, only Approach Control has any responsibility for en route traffic, which includes the scenario you described in your question. <S> Second, note that the VFR sectional chart always requests en route pilots to contact Approach, not Departure: <S> FWIW, I was also taught that "Departure" is used only when actually departing a field and that all 'pop-up' communication with the TRACON should use "Approach"; this is in line with the information above. <A> I don't think it much matters, and at almost all fields, Approach and Departure are on the same frequency. <S> But to get really precise about it, I think you should consider it from the perspective of the facility you are contacting. <S> If you are flying towards that facility, you are essentially approaching it (even if your destination is elsewhere), and should talk to Approach. <S> If you are flying away from that facility, talk to Departure.
|
For flight following, more important than picking between approach and departure frequencies, is to contact the TRACON on the frequency for the airspace that overlies your position.
|
Why use plywood to hold the bearings for the airbrakes on a fibreglass glider? The ASK-21 is mainly a fibreglass construction. However, the bearings for the airbrakes and their control rods are fitted into small pieces (some 10 cm wide) of what seems to be plywood molded into the fibreglass. The following picture shows the plate holding the bearing for the airbrake, seen from the rear side in the space in the fuselage where the wing spars are joined. The bolt that sticks out holds the bearing of the linkage that transfers the brake movement to the rods in the wing. The last picture shows the bearings in the wing where the rod to lift the actual air brake is fastened. What is the reason for this choice of material - could the bearings not be fitted into the fibreglass structure without extra pieces of plywood? <Q> This use of plywood is not ideal, but it works. <S> The wood soaks up the epoxy and becomes an integral part of the fiberglass construction, and is easy to mold, so laying up the same geometry from glass fibers alone would be much more laborious. <S> Also, plywood is reasonably isotropic , at least in the two directions of the plywood layers. <S> If you want to achieve similar isotropy with glass fibers, you need to interweave them - just wrapping one roving around the bearing will not do. <S> You could use other materials - aluminum would do, but doesn't bond as well to the epoxy resin. <S> That Schleicher uses plywood has historic reasons. <S> They used to build gliders with wood, some had steel tube fuselages, but wood was their primary construction material. <S> When they started to build glass fiber gliders (the first was the ASW-12 , which was a commercial version of the D-36 , on which Gerhard Waibel cut his teeth as a glider designer and won the German gliding championship in 1964) they used what they knew best. <S> And it worked. <A> For some bearings, you need a sufficent thickness of the socket and supporting structure to deal with bending moments on the rods/bolts, plus you need to transfer the point loads into the wing structure. <S> Together with the top glass laminate <S> you get a lightweight, yet sturdy structure (essentially a sandwich). <S> As already stated, (ply-)wood is a surprisingly fabulous material. <A> Making a thick spot in fibreglass (to support a point load) is actually a little tricky. <S> The resin produces heat as it cures, so if you have too much in one spot it can get so hot that it produces smoke. <S> Instead you need to build it up in layers, with a wait of a few hours between each set of layers. <S> Too fast <S> and it overheats, but you also can't leave it too long or it won't bond well to the cured resin. <S> If you don't plan well, you end up working through the night. <S> It's much faster and easier to slap in a block of wood, and do the whole job in one go.
|
Plywood is well suited for this task, while being lighter, cheaper and easier to build and machine than aluminum or fibre-reinforced plastics.
|
What safety features prevent jets sucking in ground staff or equipment? There have been some gruesome deaths involving ground staff being sucked into jet engines, presumably because the engine thrust was set well above idle. Are there safety features (besides prudence on the flight deck) that are designed to mitigate this risk? <Q> No, there are no safety features . <S> Only safety procedures on the flight deck and on the ground. <S> Basically it all boils down to that nobody may go near any aircraft (jet or prop; they are both similarly dangerous) <S> that may have engines running. <S> When starting the engines, the pilots first turn on the beacon (the red flashing lights on the belly and tail), then check the ground crew has left and only then start the engine(s). <S> And similarly upon landing, the pilots shut the engines down, wait a bit to let them spool down and turn off the beacons; then the ground crew should ask (via radio or the wired intercom connected to a socket at the nose) whether the engines are indeed off and only then they may start working. <S> Since start-up normally only happens after push-back, so away from the terminal, there is usually no risk then. <S> Upon arrival however the ground crew needs to come to the aircraft relatively quickly and insert chocks to the wheels, so the correct procedures are important. <S> Here see a recent accident where ground worker was injured because the procedures were not followed (he was coming from the rear, so he was only blown away, not sucked in). <S> In that incident, the engines were at idle. <S> They are still very dangerous in that case. <S> I found an Airbus document which shows danger areas, for A320 with CFM56 engines, at idle as: suction danger 2.2m (7.2ft) from engines (semicircle forward and to the sides of the engine and back to 1.5m behind the inlet) and exhaust danger to 55m (180ft) behind the nozzles with 30° spread with exhaust velocity exceeding 105km/h (65mi/h) for 17m (55ft) aft of the nozzles. <S> At full power the suction area grows to 5.9m (19.5ft) radius and the exhaust danger to 275m (900ft) with velocity over 105km/h down to 150m (500ft) aft. <A> Ground operations are complicated and dangerous. <S> You can find some details about risks and hazard zones associated with operations on the ground, here. <S> Precautions taken to minimize risk are (among others:) <S> Everyone must be clearly visible. <S> Ground personnel always wears high visibility clothes including high visibility vests, and trousers with high reflectivity stripes (even during the day.) <S> The tarmac is well lit. <S> Operations cease on extremely low-visibility situations. <S> Cockpit to ground communications: The ground will inform the cockpit that they are cleared to start-up the engines. <S> The ground crew will make sure that no person or object is in the hazard zones of the aircraft. <S> Jet blast deflectors are used where necessary. <S> This went infamously wrong in this instance. <S> The spirals painted on jet-engine spinners are used as visual cues from the ground crew that the engine is on (this is somewhat anecdotal: <S> the spiral on a spinner that is slow-spinning because of the wind will be still visible as a spiral but the spiral becomes a gray point if the engine is spinning while it is in operation.) <S> Airport signs and ground markings, such as these: Ground marshaller and wingwalker signals <A> Spool down times for various engine types allow ramp agents like me to routinely avoid being ingested.i.e when Aircraft is coming up the j-line via direction from ramp agent the rest of the crew maintains a safe distance from the approaching aircraft until appropriate time passes per aircraft at arrival. <S> You can only get ingested once in your life but you can get blasted by jets several times.
|
A special indicator light will be on when the engines are about to be started/are running (for example: the Anti-Collision light for the B737, and the Beacon light for the A320.)
|
Why are flight recorders generally located in the tail? Is there a particular reason why FDRs and CVRs and associated similar bits of equipment are kept in the tail section of a plane? <Q> When an aircraft is crashed, the entire front of the aircraft is expected to act as a crush zone . <S> By placing FDRs and CVRs near the tail, the shock wave that reaches FDRs and CVRs is reduced significantly. <S> The probability of survival based on seating is shown in this picture: ( Image Source ) <S> Hence one can see that the shock wave reduces as it reaches the rear of the plane. <S> That is the reason FDRs and CVRs are installed in aircraft's empennage section. <S> ( Image Source ) <S> Please note that the precise location of the recorders depends on the individual plane. <S> Sometimes they are located in the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft. <A> The reason for the FDR and CVR to be located in the rear of the aircraft is because that gives the best chances of recovering them. <S> Usually an aircraft has a forward speed when it crashes. <S> The initial shock of impact is absorbed by the forward part of the aircraft, resulting in a more gradual deceleration for the aft parts as the aircraft breaks up. <A> In addition to Farhan's excellent answer, it should be noted that reducing the peak impact shock is not the only reason that the FDR is placed in the tail, and that the passenger survivability is higher behind the wings. <S> The wings are full of fuel, and when the tanks rupture during a crash the fuel tends to spill forward . <S> If you look at crash videos you will notice two common scenarios: <S> In incidents in which the plane scrapes along the runway, friction with the ground starts a fire. <S> In this scenario the rear of the plane is engulfed in flames, but that is the exterior. <S> When the plane comes to rest, either the whole vehicle is engulfed or the fire recedes to small flames on the parts touching the ground: <S> the engines and undercarriage. <S> In incidents in which the plane collides with the ground and does not scrape, the fuselage and wings rupture and fuel spills forward. <S> In these cases the fires are mostly in the front portion of the craft, and the broken fuselage allows the fire to quickly spread to the interior of the craft. <S> These fires are much more dramatic and look like explosions due to the high quantity of fuel and fuel vapor being available. <A> In the USA, there is a legal requirement <S> (e) <S> The recorder container must be located and mounted to minimize the probability of rupture of the container as a result of crash impact and consequent heat damage to the recorder from fire. <S> (1) Except as provided in paragraph (e)(2) of this section, the recorder container must be located as far aft as practicable , but need not be outside of the pressurized compartment, and may not be located where aft-mounted engines may crush the container during impact. <S> (2) <S> If two separate combination digital flight data recorder and cockpit voice recorder units are installed instead of one cockpit voice recorder and one digital flight data recorder, the combination unit that is installed to comply with the cockpit voice recorder requirements may be located near the cockpit.
|
By putting the FDR and CVR in the back the acceleration is reduced allowing for a higher probability of them remaining intact.
|
Is there any limit by FAA on the age of aircraft to be operational? Is there any restriction by FAA that one can not fly a plane older than 'X' years? If someone is maintaining an older plane (e.g. from 1990s), are there any regulations which prevents or restricts that person to fly that airplane? I am interested in finding out both for commercial and smaller general aviation airplanes. <Q> It depends on the aircraft, but in general the answer is that there are no regulatory age limitations, and indeed we have many aircraft flying that are 50+ years old. <S> A notable exception is the Robinson line of piston helicopters. <S> The airframe on those helis is limited to 2200 hours or 12 years , whichever comes first, at which point the entire airframe must be completely overhauled. <S> Some of the airframes are indeed rebuilt, but some are also scrapped, depending on level of wear and corrosion. <S> Since the airframe lifetime is in the LIMITATIONS section of the POH, it is governed by: § 91.9 Civil aircraft flight manual, marking, and placard requirements. <S> (a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry. <A> N60094 , a 1909 Bleriot XI based at Rhinebeck Aerodrome Museum, has a valid FAA airworthiness certificate . <S> So I think it's safe to assume there are no FAA restrictions based solely on age. ] 1 <A> Aircraft hulls are limited in the wear and tear they can withstand due to metal fatigue that can develop (pressurized aircraft more than non-pressurized). <S> The manufacturer will impose limits on the flight time of the hull (an older airframe will be considered not airworthy) <S> so any developing metal fatigue will not tear apart the plane in flight like what happened with the Comet or Aloha Airlines flight 243 . <S> tl;dr <S> it's the responsibility of the manufacturer to impose limits on the airframe age. <A> According to Wikipedia the DC-3 <S> first flew in 1935, entered regular passenger service in 1936, and as of 2012 #10 off the production line was still in regular commercial service. <S> I'd venture to say it's got more to do with maintenance than regulation. <S> (I'm sure someone will quote the appropriate FAR section in a few minutes.) <A> As a general statement aircraft are pretty well-built <S> (in fact, they are generally overbuilt <S> so they'll hold up to use and abuse in excess of their stated design tolerances), and carefully maintained. <S> The most common restriction you'll encounter <S> that's similar to what you're asking about <S> is what are known as "life-limited parts" - Aircraft components that have a finite limit (expressed in flight hours, flight cycles, or calendar time), after which they must be replaced or overhauled. <S> These limitations are usually given by the manufacturer (in a Limitations section of the POH/AFM or Maintenance Manual, which has regulatory effect under FAA rules). <S> In some cases an entire airframe may be life-limited: <S> ( The R22 helicopter has both a calendar and hours limit, and commercial airliners typically have a flight cycle and flight hour limitation on the airframe as well. <S> In other cases only a component may be life-limited: <S> The wings on a Grumman Tiger or a Piper Tomahawk must be replaced after a certain number of flight hours. <S> Even in absence of a specific limitation it's important to recognize that all airframes have <S> a finite life - components will eventually suffer fatigue and fail, as with any kind of mechanical equipment. <S> Manufacturers may recommend extensive inspections of older aircraft to ensure that fatigue is detected before the structure fails. <S> (For example, while the Piper Cherokee family has no Limitations published Piper does recommend extensive inspections on aircraft that have accumulated a large amount of flight time.)
|
As such there is generally no regulatory restriction on airframe age , though there may be other applicable restrictions (or recommendations) depending on the aircraft.
|
Why doesn't an airfoil rotate? As far as I understand, two of the reasons how an airfoil generates lift are Coandă effect and downwash . However, if there is upwash near the leading edge, why isn't an airfoil rotated by the two forces (upwash at the front and downwash at the back of an airfoil)? <Q> It does rotate. <S> In fact, in aerodynamics, this rotation force has a name: pitching moment . <S> Pitching moment changes depending on the angle of attack. <S> Airfoils can be designed with almost any pitching moment and still generate lift, from positive (trailing edge rotates upwards as you describe), to zero (no rotation) to negative (trailing edge rotates downwards). <S> In general, high lift airfoils have positive pitching moment (because, as you noticed, downwash caused by the Coanda effect increases lift). <S> But zero and negative pitching moment airfoils are useful for tailless and flying wing aircraft. <S> Helicopter blades are long, narrow and flexible so must use zero pitching moment airfoils to prevent them twisting. <S> If you use an airfoil with a positive pitching moment you need something to counter the rotation. <S> For most aircraft the solution is the horizontal stabilizer (the tail). <S> An alternative solution is the canard. <S> For chevron shaped (V-shaped) flying wings and tailless planes <S> the solution is to twist the wing (in regular planes it's called washout but flying wing designers call it "twist"). <S> The twist causes the wing tips to have less angle of attack (sometimes negative) so that the overall rotation force for the entire aircraft is zero. <A> There are no two (aerodynamic) forces. <S> Force is not caused by the up- or downwash itself, but by the change from up- to downwash. <S> The air is only accelerated downward and this change in it's momentum causes an upward force on the wing everywhere, there is no aerodynamic down force. <S> Due to the pressure distribution however the centre of lift is about quarter-chord for subsonic airfoils and changes somewhat with changes in attitude. <S> There however obviously is a down force, gravity. <S> If the centre of gravity and centre of pressure are offset relative to each other, there is a moment that rotates the aircraft. <S> That's why a plane needs horizontal stabilizer with elevators that allow shifting the centre of lift by adding a bit of controllable lift far from the centre of lift of the main wing. <A> Perhaps you're thinking of something like a fanwing , which incorporates both centrifugal fans and an airfoil into the wing <A> You are right, lift is concentrated in the forward part of an airfoil, especially at high angle of attack. <S> If you take a single wing and drop it, it will start to rotate around its spanwise axis quickly. <S> This effect is called autorotation (not to be confused with autorotation in helicopters, though!). <S> Model aircraft pilots should have seen that before: When a model breaks apart in midair, its wing will in many cases autorotate to the ground. <S> In an airplane this can be avoided by shifting the center of gravity near the center of lift and by adjusting the lift distribution either with a tail surface, a canard or with wing flaps such that the center of lift is exactly over the center of gravity. <S> Flying wings can do this without a separate tail surface, but need special airfoils which show little change in the location of the center of lift over angle of attack. <S> Below you see the pressure acting on an airfoil symbolized by arrows (yes, that is XFOIL at work), and arrows pointing at the airfoil indicate pressure higher than ambient air pressure, and those pointing away from it indicate suction. <S> Their length is proportional to the magnitude of either pressure or suction. <S> This shows that the forces in the forward part of the airfoil are more intense than those in the rear part. <S> The aerodynamic forces which depend on the angle of attack are focused at the quarter chord point, and without added balancing masses of a fuselage and engines, will be forward of the wing's center of gravity. <S> Of course, this is strictly true only as long as we have no flow separation. <S> Once rotation starts, separation is unavoidable above the maximum angle of attack. <S> However, inertia will keep the wing spinning until the trailing edge points forward and a similar pressure distribution develops. <S> This gives the rotation another push and keeps the wing spinning over a full revolution, and the whole process starts over. <A> <A> If the airfoil is cambered (in other words unsymmetric looking sideways) it does indeed rotate. <S> This is why the control surfaces are needed with a preferably long moment arm and why building flying wings is difficult.
|
Because the horizontal stabilizers provide a counter force to the plane in its entirety so the pitch remains stable.
|
Are the military tilted-thrust aircraft in the film Avatar feasible? As full-scale aircraft or as models / UAVs / drones? Is anyone working on making these real or are they fundamentally flawed designs, or needing new materials to be invented? <Q> I presume you're talking about the fictional Aerospatiale SA-2 Samson . <S> From that page: Ducted fan VTOL aircraft have been flown since at least the 1960s. <S> A notable example was the Bell X-22 , a quad-ducted fan experimental aircraft built for the US military. <S> It has no relation to the later V-22 Osprey tiltrotor. <S> Though successful, no military aircraft since have used that technology. <S> The Bell X-22 looked like this: which has similar overall characteristics to the SA-2 depictions. <A> They are feasible in as much as the atmosphere on "Pandora" is thicker and the force of gravity is lighter. <S> C.f. <S> Avatar Wiki <S> This allows for both large winged reptiles (?) <S> and smaller tiltrotors than are possible on our current earth. <S> 1 <S> 1 <S> There is evidence that our atmosphere was more oxygen-rich in the geologic past and may have been thicker, allowing for similarly large reptiles. <A> In fact, one basically exists already: the V-22 Osprey . <S> The main difference being that the V-22 has ailerons for roll control and wings for lift in forward flight. <S> Power isn't a problem, it's just a multirotor helicopter... think <S> Chinook, on a different axis. <S> And control, for the most part, isn't a major issue. <S> Differential power to the two motors provides Roll control, similar to a quadcopter Rotating the rotors slightly forward/ <S> back and/or something similar to a cyclic on a conventional helicopter allows (similar to the Osprey tiltrotor): <S> Forward <S> /reverse flight (if tilted together) <S> Yaw control (if tilted in opposing directions... think <S> tank tracks If attached in away that they can be angled up/down, pivoting on the attachment to the fuselage <S> , the vehicle can "strafe" (ie lateral sideways movement) <S> Pitch when in forward/reverse flight is provided by the tail stabilisers. <S> In the hover it could presumably be controlled to some extent by means similar to a conventional helicopter's cyclic, shifting weight, or by an additional small rotor near the tail, if you didn't want to be 100% true to the movie model <S> Here's a working model , for example.
|
Yes, they are certainly feasible. I don't believe there are any full size models, but the Osprey is "close enough" to prove the concept.
|
Can seaplanes land on normal airfields or in a marsh or muddy area? I know there are some amphibious planes which can land on both water and land but how different is the their landing in comparison to that of a normal small aircraft? Also, if seaplanes needs to go into some marsh, will that work for them? <Q> Back in the early 1970s I belonged to a Civil Air Patrol (CAP) squadron that had a J-3 cub with an 85 horse engine on it. <S> During the summer we would operate it on floats, during the winter on wheels. <S> At the end of summer, we would land it on the grass alongside the runway at the Springfield, OR airport (no longer there, it's a big Walmart now ) and replace the floats with wheels. <S> In late spring, we'd replace the wheels with floats and take off from the grass. <S> The joke was that for takeoff you were supposed to line up all the cadets and have them pee in unison along the path the floats would take to aid in the takeoff. <S> Actually, that wasn't necessary since western Oregon gets a lot of rain. <S> Even with wet grass though, for the takeoff we'd get the initial movement by pushing, and we were always careful to ensure that the grass had nothing on the takeoff path that would damage the floats. <S> With the floats on, you could fly when the airspeed said 40 mph (yes, it was indicated in mph) which is about 35 knots. <S> You could generally count on at least 5 knots of wind right down the runway when it was raining, so at 30 knots across the grass you were good to go. <S> You can go to YouTube and search "floatplane landings on grass" to see some examples of landing on grass. <S> " <S> Floatplane takeoffs on grass" will show some takeoffs, but a quick look showed using a dolly, which I think we did once or twice before my time with the group but then figured it was easier to just use the grass. <A> airfield: <S> The hull or floats would be badly damaged. <S> An amphibious aircraft can land on both water or a normal airfield (pavement, grass, gravel, etc.), because it has both wheels and floats, but with amphibious aircraft you're either operating as a seaplane (on water) or a landplane (on solid ground), and you would follow procedures appropriate to the type of operation you're conducting. <S> As I understand it amphibious aircraft would not be suited to landing in a "marsh" or "swamp": The water and mud would render the wheels ineffective (and possibly dangerous: If the wheels dig in to the mud the aircraft could flip over), and the dirt/land portions of the area would damage or destroy the floats/hull. <S> It may be possible to put the aircraft down in such an area, but it would be very unsafe, bordering on reckless , to do so in a non-emergency situation. <A> Seaplanes can land on land (pun intended) if the ground has a soft cover. <S> This could be snow, tall grass and landing in a wet peat bog is also possible. <S> However, any solid object close to the surface (logs, stones) will damage the hull. <S> Historic cases are the landings of Amundsen with a Dornier Wal on arctic ice or the landing of Gronau's Wal when it was transferred to the Museum in Munich (actually, this was the same aircraft). <S> It was landed in winter on a snow-covered meadow close to the Isar river in central Munich. <S> This was in no small part possible due to the flat hull shape of Dornier flying boats. <S> They were optimized with water tunnel studies for the heavy and inefficient engines of their time. <S> Modern hulls have a keeled shape, where the bottom is v-shaped to reduce the load factor when planing in rough sea. <S> Landing such a seaplane on land needs more snow and should not be attempted on grass.
|
A pure seaplane cannot land on a normal (land)
|
Do helicopters have trim? How does it work? I recall having read somewhere that “helicopter in forward flight behaves just like a badly trimmed airplane”. So I'd like to ask: Do helicopters have trim? If so, how does it work? And is the helicopter stable when properly trimmed? <Q> It depends on what you mean by trim. <S> If you mean a a mechanism that allows the pilot to reduce the control forces in order to allow the helicopter to be flown hands off, then the answer is a qualified yes. <S> If you mean a trim tab attached to a control surface, then the answer is no. <S> Many airplanes which have a trim control do not use a trim tab. <S> For example, Pipers have an anti-servo tab on the elevator, which the pilot uses to reduce control forces. <S> Since helicopters are unstable -- meaning if you take your hand off the cyclic the aircraft will be in an unusual attitude within a second -- nothing short of electronics and actuators will allow a heli to be flown hands off. <S> But every heli except the smallest ones, have considerable stick forces, which make them difficult to impossible to handle without some kind of assistance. <S> The simplest setup is what you find on the original 4-seat R-44 Astro, which lacked hydraulic assist. <S> On top of the cyclic you will find a 4-way "hat" switch which uses electrical actuators on the cyclic to reduce the control forces necessary to fly it. <S> Larger helicopters have hydraulic assist, which allows the copter to be controlled with just two fingers. <S> Inop hydraulics is considered an emergency. <S> Big helicopters have a stability augmentation system , which allows the helicopter to be flown hands off. <S> An SAS is required for IFR flight. <A> Helicopters with hydraulic actuation of the swash plate usually have an artificial feel spring. <S> The neutral position (where the stick returns to if released) of this feel spring is the trim position. <S> The pilot holds the cyclic at the position where the helicopter has a steady flight path, and can then trim the feel force away by adjusting trim position in two possible ways: <S> Beep trim. <S> A 4-way china hat switch at the control is deflected by the pilot, resulting in slow continuous adjustment of the neutral spring position. <S> With a stick held in position, the feel spring forces are gradually reduced until the pilot stops deflecting the switch when feel force is zero. <S> Trim release. <S> A push button that effectively removes all feel spring force: neutral spring position always follows stick position. <S> With trim release ON the stick can easily fall over if friction is low. <S> Pilot places the stick at steady flight path, then switches trim release OFF. <S> The feel spring is now effective again. <S> Is the helicopter stable when properly trimmed. <S> We need two answers here, for forward flight and for hover. <S> In forward flight: <S> Directionally, yes. <S> Pitch - often, if the heli has a horizontal tail. <S> Depends on position of horizontal tail relative to rotor downwash, which varies with airspeed and gross weight. <S> Roll - usually not. <S> That's considering aerodynamic stability only, an AFCS with heading & altitude hold would make for a docile trim situation. <S> In hover: it's all unstable everywhere, like trying to keep your balance when standing on top of a large inflatable ball. <S> "Trimmed" has very little meaning in the hover. <A> The R-22 helicopter has both cyclic/collective friction, as well as a trim. <S> When you are hovering, you are using a lot of tail rotor to counteract the spinning of the blade, and there isn't any force to counteract it. <S> The tail rotor, while countering your rotation, will also push you in a direction (like a propeller), so in a hover, with a helicopter that has a counter clockwise rotation, the tail rotor will keep pushing you to the right. <S> To counter that, you have to put in left cyclic. <S> To help reduce the effort required to keep it a hover, Robinson put in a trim, which just adds a constant left input to the cyclic. <S> This greatly reduces the workload for the pilot while taxiing and hovering. <S> For example, I've used the cyclic/collective friction settings in the R-22 to tighten up the movements of the cyclic and collective. <S> This makes it much easier to read a navigation map or use the radio. <S> It allows me to take my hands off some of the controls for a whole second or two to allow me to adjust a map or tune the radio :) <A> Yes. <S> Some blades also have "trim tabs" and are critical component on the blade and require adjustment to ensure the smoothest flight.
|
The amount of trim, in the case of Robinson helicopters, is not pilot adjustable, but it is a trim setting, technically speaking, which is separate from the friction settings, which helicopter pilots can/do use in the same way fixed wing pilots would use a "trim". Some will use a "trim" function to hold the cyclic or collective stick in place to prevent rapid changes in the blades pitch.
|
What are the ways to keep the birds away from airfields? I know bird strikes are a major issue for many airports, and that measures are taken to keep birds away. There are some obvious things airports can do like not to have any stray garbage, food, etc. in the open, but I'm sure other less obvious methods are also used. What exactly are some of the widely used techniques to keep birds away from airports? <Q> The FAA has an FAQ on bird strikes and other wildlife hazards, which includes a (broken) link to their Wildlife Hazard Management at Airports - A Manual for Airport Personnel document . <S> Chapter 9 is called "WILDLIFE CONTROL STRATEGIES AND TECHNIQUES AT AIRPORTS" and includes the following techniques: Change flight schedules Modify the birds' habitat (food, cover, water) <S> Physically exclude the animals (not so easy with birds) <S> Repel the birds with vehicles, chemicals, sound, visual objects (flags, scarecrows, fake dead animals, lasers) <S> Repel <S> the birds with trained falcons or dogs Shoot nonlethal projectiles at the birds Trap, remove and release the birds at a different location <S> Kill the birds with poison or other means <S> The document summarizes the various techniques like this: Habitat modifications to minimize food, cover, and water and physical barriers to exclude wildlife are the foundations of wildlife hazard management programs for airports. <S> In addition, an integrated array of repellent techniques is necessary to disrupt normal behavior and to stress hazardous wildlife that attempt to use the airport. <S> These repellent techniques must be used judiciously and backed by real threats to minimize habituation. <S> To this end, lethal control of selected individuals of common species is sometimes necessary to reinforce repellent actions. <A> about.com has a good article which lists the many methods that are used to scare birds away from airports. <S> It includes: <S> Modify <S> the habitat: <S> Another source: Birds at Airports - Internet Center for Wildlife Damage Management <S> (Image Source: <S> WikiMedia Commons - Author: Bluescan sv.wiki ) <A> On a visit to Blackpool Airport control tower a few years ago, they mentioned that they flew a hawk/falcon (not sure which) every day to deter birds <A> The airport authorities use a number of techniques to manage the hazard of bird strike in and near airports. <S> These include, Elimination of bird habitats- <S> Birds usually come to the airport area due to the availability of food sources. <S> Denial of food to birds by eliminating the sources (like landfills, garbage, crops, dumps etc) will reduce the chance of birdstirke by eliminating the source. <S> It also helps to keep the airport and surrounding areas unattractive to birds (for example, by eliminating water stagnation, vegetation cover etc) as it prevents the birds from nesting there. <S> Scaring them away- <S> A number of airports use a number of bird repellents like pyrotechnics, cannons (mostly just prior to aircraft approach to prevent bird habituation), chemical repellents etc. <S> In some cases, specially trained animals (like falcons, dogs etc) have been used to scare away the birds or they are trapped. <S> In some cases, the flight schedule can be altered if bird movement is expected in the area (for example, if the airport is on a bird migration route). <S> The problem can be solved by simply killing the birds in the area, though this drastic step is usually not implemented except in the most extreme cases. <S> In general, the nesting sites of birds are destroyed to prevent them from staying permanently near the airport. <S> Usually, a combination of above methods is used to manage the birds. <S> The only procedure available for flight crews is to either delay the flight (or land in alternate runway if its available) in case birds are detected over an area. <S> This however, is dependent on a number of variables like fuel availability, flight schedule etc. <S> There are some radar systems under development that could detect birds; however, these have not reached operational stage yet. <A> Trap, kill, harass, or deprive them of food and shelter. <S> The number of bird strikes at my airport has been reduced dramatically by consistently harassing the birds to the point where the birds eventually adapt and learn. <A> All the correct information has been added except one point. <S> The engines nose spinners have a design painted on them. <S> Once the engines are running the design is suppose to look like the eye of a bird of pray to scare off birds in flight. <S> Does it work I can not say <S> but they claim it does.
|
Remove sources of food, such as seed-bearing plants, use insecticides to eliminate insects as a food source, remove bushes and plants that can be used for nesting The use of visual devices (lasers) or audio (sonic cannons, recordings) to scare away birds Trained falcons, dogs, or other predators to make the airport inhospitable to birds.
|
Do flight tracking websites also track non-commercial and defense aircraft? Many flight tracking websites have the data about almost all the commercial airplanes in air. Do they have the data about the private jets and/or defense aircraft also and they just don't show that on the websites? <Q> As long as an aircraft transmits (unencrypted) ADS-B information, anyone within radio range can track it. <S> The equipment necessary to receive ADS-B can be as simple as a computer with a TV receiver (USB DVB-T module) and the right software. <S> Receivers can then send the data stream to, for example, Flightradar24 , who will display it on their website. <S> As Flightradar24 states, not all aircraft are equipped with an ADS-B transponder, and even those that do may not have switched it on. <S> Unless ADS-B is installed and operating, it would not be visible. <S> @ezra-g mentiones that Steve Jobs' aircraft was blocked , but this is of something one would have to ask for, and the site has to apply the filter so it doesn't display on its website. <S> However, Jobs' plane would still have been visible on the receiving computers. <S> And, of course, the website will only filter your aircraft if they are willing to do so, either on request, through payment, or a government order. <S> Flightradar.com also has some other data sources, like FAA (Federal Aviation Administration) <S> radar information in the US, which also contains aircraft without a transponder. <S> The FAA may also filter some aircraft. <A> From the FlightAware FAQ : <S> How does FlightAware handle flights around the world? <S> What is FlightAware's service area? <S> FlightAware's primary service area includes airspace operated by the United States (including Alaska, Hawaii, Puerto RIco, and Guam), Canada, the Caribbean, Australia, the United Kingdom, and France. <S> Flights in the primary service area support real time maps, departure and arrival information, delays, and more. <S> FlightAware's secondary service covers scheduled major airline operations at any airport in the world. <S> Flights in the secondary service area support departure and arrival information. <S> Secondary coverage areas may have real-time positions for ADS-B equipped aircraft operating in FlightAware's ADS-B coverage area. <S> Additionally, some airlines send FlightAware satellite position reports from aircraft worldwide that augments other position data and provides transoceanic coverage as well. <S> For flights arriving in a service area from outside of a service area, FlightAware will be able to track the flight when it nears a service area. <S> For flights departing a service area, FlightAware will be able to track the flight until it leaves the coverage area. <S> Flights may not be tracked beyond that point unless they enter another service area. <S> Not all worldwide data sources (e.g., European data, datalink ARINC/SITA ACARS, etc) are freely available on FlightAware.com due to government regulations or commercial arrangements. <S> You can contact us if you have a commercial need for worldwide data. <A> Privately operated aircraft are included as long as the owner of the aircraft has not specifically requested that their aircraft be excluded from public searching. <S> For example: Steve Jobs' private plane's N-number was public information, but it was excluded from tracking on Flightaware. <S> Military aircraft are not included in public ADS-B tracking information. <S> For more on ADS-B and flight tracking, see the information from FlightRadar24 and FlightAware . <A> Flight-tracking sites <S> can track military aircraft, but generally don't . <S> For example, I live near a USAF base and can easily track dozens of military flights a day with an ADS-B receiver, but not one of those flights has ever shown up on FlightRadar24. <A> Yes, recently PlaneFlightTracker provided exactly this live service both for NATO and Russian Military aircrafts as well as Medical, Emergency, Safe and Rescue helicopters and airplanes. <S> It starts with a procedure explaning how to track as well as Live Military Aircrafts Maps. <S> This site uses the FlightRadar24 map for embedment but has made an effort to extract necessary ICAO codes so that the users may get the proper maps.
|
Flight tracking websites, such as FlightRadar24 and FlightAware , generally track aircraft using publicly available ADS-B transponder information.
|
How flat does a runway need to be? I always assumed that big runways are flat (or more specifically straight: they might have a slight slope in either direction), but while watching some crosswind landing footage shot at Birmingham Airport I noticed that the runway looks really uneven, and based on the videos it looks like this hinders safe landing especially in adverse weather conditions. How common are uneven runways like this? Does an uneven runway make landings more difficult? Is there any standard on how flat a runway needs to be? <Q> As an anecdotal answer to your first two questions, paved runways used by air carriers that have obviously noticeable vertical curves are a minority but not uncommon. <S> Unless they've redone the runway at Stansted, north of London, there's a significant hump in the middle. <S> I used to operate through it at night in the early 1990s. <S> As a bit of fun, we'd arrange legs so that a new first officer would have the leg into Stansted. <S> On final at night the hump was not noticeable. <S> However, when you touched down, the runway lights along the last half of the runway would disappear, at which point the captain would observe, "Hmm, not much runway left." <S> If you define a runway simply as a strip of land regularly used by aircraft, there's a whole lot of them that have vertical curves, and many with horizontal bends as well. <S> It's gone now, but there used to be a strip at a lumber mill in North Fork, California, that had a 10-15 degree bend in the middle. <S> McKenzie Bridge airfield just upriver from my home in Oregon <S> has a steep incline on the east end. <S> If the runway qualifies as an uphill/downhill runway, you generally takeoff downhill and land uphill. <S> Touching down on the downside of a hump can make your landing feel a little softer than otherwise. <S> Touching down on the upside of a hump makes it a little harder than otherwise. <S> Accommodating a horizontal curve is more challenging. <S> It's worth remembering, though, that seaplanes often use a curved takeoff run. <A> Given that the runway is over 3000m, those undulations don't look very big. <S> I doubt they had much to do with the landings in the video. <S> It's hard to make something that long completely flat. <S> The FAA has advisory circulars for all sorts of stuff in and around an airport. <S> One does cover flatness. <S> Airport Design Advisory Circular Page 77 has recommendations on gradients including: Vertical curves for longitudinal grade changes are parabolic. <S> The length of the vertical curve is a minimum of 300 feet (91 m) for each 1.0 percent of change. <S> A vertical curve is not necessary when the grade change is less than 0.40 percent. <S> Unfortunately, I could not find measurements of the undulations at BHX online, and I'm not going to estimate it from that photo. <S> Would be nice to know how much above or below these particular recommendations it is. <A> Based on ICAO ( doc9157 Aerodrome design manuel part1 runways), the standard of vertical and horizontal slope of runways is: For Horizontal Slope 1-1.5% for code letter C,D,E,F 1-2% for code letter A and <S> B <S> Except intersections of another runway/taxiway where slope can be falter <S> And for Vertical Slope Slope between max. <S> and min evaluation of the runway centre line should be : Code number 4: overall <1%, 1st and 4th quarter <0.8%, the other half <1.25% Code number 3: overall <1%, 1st and 4th <S> quarter <0.8%, the other half <1.25% Code number 1/2: overall <2% <S> For slope change between 2 consecutive slope should be: <1.5% for code number 3/4 <2% for code number 1/2 <S> And for transition from one slope to another should be: <0.1% per 30m code number 4 <0.2% per 30m code number 3 <0.4% per 30m code number 1/2 <S> This is the global standard, <S> some aviation authority such as FAA my have stricter rules
|
Landings and takeoff on uneven runways are not significantly more complex than on straight runways.
|
Do nacelles around aircraft engines help in reducing the engine sound? I know that the nacelles around the aircraft engines are actually a housing and are generally lightweight and have may components like inlet cowl, fan cowl, etc., but do they help in reducing the engine sound as well or are they just for housing? Even if they help in reducing the sound, then how much % of sound has been reduced by them? Is there any quantitative analysis available for that which can show that without housing engines were creating sound at X dB, and after nacelle and proper housing of all other components, the sound has been decreased to Y dB? <Q> Take a modern turbofan : The tips of the fan run at approximately Mach 1.5 . <S> We know from unducted props that supersonic tips make them very noisy . <S> The same turbofan without the shroud would be extremely noisy, too. <S> Acoustic liners on the inside of the fan shroud have major contribution in suppressing this noise source. <S> But there is more: The nacelle also makes it possible to put an intake in front of the fan which helps to equalize flow conditions over the cross section of the intake and to accelerate or slow the flow of air to just the right amount for the engine. <S> Without the intake, the engine would suffer from frequent compressor stalls and surges, so the nacelle in effect widens the operating conditions and avoids those noisy incidents , too. <S> Another important source of noise is the nozzle: Here the hot, fast gas from the engine is ejected into the surrounding flow, and the mixing of both creates most of the engine noise . <S> Note that noise increases with the sixth to eighth power of jet velocity, so the most dramatic noise reduction is possible with higher bypass ratio engines. <S> Diagram from the Stanford web page linked above. <S> The jet velocity is in ft/s. <S> By serrating the trailing edge of the nozzle, this mixing process can be slowed down somewhat and the noise level can be reduced . <S> Without the nacelle the engine would create much less thrust and more drag, and bigger, more powerful engines would be needed. <S> Bigger engines would create more noise, too, so this is also an indirect way how nacelles help to keep noise down. <S> Fan blade failure is all but silent, but if the blade fragments would escape at high speed, the noise of what follows next would also be considerable. <A> As you have correctly mentioned, the term Nacelle generally refers to a number of sections around an aircraft engine (In the context of turbofan aircraft engines). <S> This generally the structures formed by the Inlet, Fan Cowl, Thrust Reverser and the Exhaust. <S> The nacelle does perform the basic function of a housing for all these subassemblies which means it contributes to protection of the engine from the elements and the environment from the engine <S> (Say a blade failure). <S> But its major function is to provide an aerodynamic body which can house the mechanicals of the engine, the pneumatic ducts, fuel lines and electrical wiring. <S> The nacelle can therefore provide noise reduction by reducing the drag-noise which would be otherwise generated. <S> This is through the aerodynamic design and the various features built into the subassemblies such as Acoustic Liners used extensively througout the nacelle which convert acoustic energy into small amounts of heat. <S> This is a major source of noise-reduction in modern aircraft engines. <S> Exhausts are the biggest culprits when it comes to aircraft engine noise and as such, the exhausts are designed to create a 'mixing' area where hot air from the exhaust is mixed with ambient air to reduce the exhaust noise. <S> I guess I'm just trying to say that the nacelle is formed of these various subassemblies and therefore their individual contribution towards noise reduction is very important. <S> As far as a quantitative study on the reduction of noise, I could not locate any as therefore can only manage to answer the first part of your question. <S> Sidenote: <S> Modern Inlets also use Laminar-flow design (777X for example) which contribute to immense fuel savings and very minor drag-noise reduction (Probably negligible). <A> The nacelles themselves reduce sound just by being another barrier before the sound gets to you for the most part. <S> It's there to provide airflow around engine components, better aerodynamics, protection from elements, and depending on what kind of engine it is, it "may" help with noise reduction some (Turbofan). <S> On turbine engines, there are exhaust airflow options that do suppress the noise . <S> This is not a nacelle, it's a noise suppression nozzle.
|
A last noise reduction contribution to mention here is the capacity of the nacelle to contain the shrapnel from a failed fan blade.
|
How or when can the 250 KIAS speed limit below 10,000ft be exceeded? This arose out of a comments discussion in this question . The only airspace I really know is the UK. Here, a controller may issue a clearance to exceed the 250kt limit below 10,000ft for reasons other than minimum safe flying speed, e.g. to expedite a transition for spacing. Is this common, e.g. in the US? I know it's open ended but I'm interested in whether this is just some "local" thing. <Q> Not a local thing at all! <S> In Australia, it is extremely common to hear, especially for aircraft on departure. <S> Listening to LiveATC, particularly Sydney International Approach/Departure (YSSY) you will quite often hear ATC give an aircraft permission to exceed 250KIAS below 10,000ft. <S> Qantas 123:Approach, QFA123, with you passing 2,300, climbing 5,000.. <S> Sydney Approach: <S> QFA123, Identified, <S> Climb FL240, cancel speed restrictions below 10,000.. <S> There are a number of reasons this is used. <S> The first, I have already hinted to in the example radio call above. <S> This gives better separation for aircraft departing in the same direction. <S> For example, one of the busiest sectors in the world is Sydney - Melbourne Australia. <S> The common SID's out of Sydney for Melbourne are the DEENA4 WOL transition and the WOL1 Departure, depending on operational runway. <S> As a large amount of aircraft use these departures, the further the lead aircraft can get on the SID prior to the trailing aircraft becoming airborne, the better. <S> Arrivals:Again, using Sydney, they receive a large amount of Regional Turbo-Prop traffic <S> (Dash 8-Q300/Q400, Saab 340B, BE350). <S> You will commonly hear Approach cancel speed restrictions on these aircraft on decent so they can give them more space on the approach. <S> They land reasonably slower than a B747/A380, so the more room, the better. <S> Another reason is simple. <S> These guys are operating commercial operations, hence faster is better, especially on descent. <S> So if there is no or low traffic in the TMA, ATC will commonly release the speed restriction on aircraft to accommodate the company operations. <A> In the US, the 250 kt speed limit is codified in 14 CFR 91.117 <S> §91.117 Aircraft speed. <S> (a) <S> Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.). <S> (b) <S> Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). <S> This paragraph (b) does not apply to any operations within a Class B airspace area. <S> Such operations shall comply with paragraph (a) of this section. <S> (c) <S> No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph). <S> (d) <S> If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed. <S> Note in section (a) that only the administrator may authorize operations below 10,000 feet MSL at speeds above 250 KIAS. <S> The only exception to this is part (d) which applies to aircraft that cannot safely operate below this speed. <S> As far as I know this only applies to specific heavy airplanes. <S> ATC does not have the authority to issue instructions contrary to regulation. <S> Historically the FAA has experimented with the ability of controllers to cancel the 250 kt speed limit within certain class B airspace, notably in the Houston, <S> TX class B. <S> That program was discontinued and currently no controller may grant you an exception to the regulation. <S> Note that the 200 kt speed limit in class C and D surface areas and any speed restriction published on a chart (departure and arrival procedures) <S> can be cancelled by ATC. <A> In the US, speed restrictions are frequently cancelled, either to ensure or to increase separation between aircraft, as per <S> ATC Handbook 4/3/14 JO <S> 7110.65V, Section 5-7. <S> Speed Adjustment : 5−7−1. <S> APPLICATION Keep speed adjustments to the minimum necessary to achieve or maintain required or desired spacing.
|
Departures:It is extremely common to hear ATC cancel speed restrictions on departing aircraft.
|
What are the major hazards in operating a PT6 Turbine Engine? I am just in the process of doing a bit of study in the hope of doing my Basic Gas Turbine Endorsement in the next few months, and just wanted some feedback/comments/discussion on the major hazards associated with starting, managing and shutting down a PT6 Turbine Engine (PT6 as it is the most common used Turbine Engine on an aircraft I will touch for this endorsement). Mainly, what I am looking at is during the start - If the EGT raises above the evil 700* mark, what is the best course of action to prevent "melting the turbine"? During Climb/Cruise Operation - What are the most common failures, and their indications? Maintenance/Shutdown - What are the most common methods of recording Cycles? By landing or by Start/Shutdowns? <Q> You MUST NOT allow the EGT or ITT (whichever is applicable) temperature limit to be exceeded in any turbine engine. <S> If it gets close to occurring during start on a PT-6, you need to abort the start by stopping fuel flow into the engine, then conduct the appropriate checklist for an aborted start. <S> Unlike the Honeywell / Garrett TPE single-shaft engines, the PT-6 normally won't get close to the temperature limit on start. <S> The Garretts I used to fly in Metroliners had to get right next to redline and stay there on every start. <S> One reason that PT-6 engines are so much more relaxing to fly. <S> On takeoff / climb, just don't exceed the maximum temp limit; regulate the power lever(s) to keep below it. <S> I've never had a failure of a Pratt except for bleed air leaks. <S> Airlines count cycles as a start, flight, and shutdown. <S> If one of these did not occur, you did not have a cycle. <A> The evil mark you are talking about varies. <S> There ara all kinds of PT6, ranging from around 500SHP to 1700SHP, each of them with different limits, including ITT limits. <S> Which PT6 are you talking about? <S> Either the starter did not crank the engine fast enough, the engine hot section is worn out or something is wrong with bleed valves/FCU. <A> Do not mix EGT and ITT. <S> EGT is exhaust gas temperature and ITT is Inter stage temperature. <S> Normally when starting a PT6 you should watch ITT and depending which PT6 model you use maximum ITT may vary but it`s around 1600 degrees Fahrenheit. <S> I work for Pratt & Whitney and PT6 <S> is probably the best engine ever made in it`s class as someone mentioned. <S> When starting a PT6 the engine will not get close to the maximum allowable ITT unless you have a problem. <S> Good engine choice hope you will have good time flying with this engine.
|
Overtemperature during start means that something is wrong with the engine.
|
How much "power" do ATCs really have? After reading this question about being cleared to go faster than 250kts in airspace that otherwise has a speed limit, I began to wonder how far can Air Traffic Controllers (ATCs) can bend the rules on an aircraft-to-aircraft basis? Is there a limit to what exceptions ATC can make for someone? I'm particularly interested for the answer in the USA, but I'm sure information about other countries would also be enlightening. <Q> As an active area radar controller, I completely agree with @rbp answer. <S> To better explain relationship between power and responsibility, I will try to describe what a controller would usually do: If I need an aircraft, for example, to reduce speed... <S> I know approx. <S> what would be the minimum convenient speed for a particular type to ask, so I'd take this into account prior asking. <S> But if a pilot tells me that he's unable to comply with the request, I'll find another solution i.e. radar vectoring to loose few miles or in extreme situation, level change. <S> In short, a controller will never force a pilot to action if pilot answers that he can't do that. <S> A controller must plan in advance that pilot may not be able to fulfil his request and have alternative solution. <S> If you, as a controller, put yourself in a situation where you have no alternative, that is usually too late. <S> There are usually only few things where I can't make exception: <S> Minimum separation between aircraft Danger/Prohibited zone Terrain <S> Even then, in extreme case, I've never met: <S> Imagine a situation where you have an aircraft which can't change level due to traffic above and below and has a crossing traffic. <S> Then only remaining action I have available is radar vectoring, but what if the pilot advises me that his unable to turn due to weather, (the described situation is usually the controller fault because he should have predicted that earlier). <S> Then controller probably would give the pilot traffic information (tell the pilot what to expect) and advise the minimum distance but it will not force the aircraft to CB. <A> As far as I know, most regs have some sort of out that says "unless directed by ATC," and ATC has two unbreakable rules which limit much of what they are allowed to do: <S> thou shall not vector airplanes into obstacles, terrain, unflyable weather or atmospheric conditions, restricted (in the lay sense of the term) airspace, or other aircraft <S> thou shall not deviate from aircraft separation Other than that <S> , when it comes to clearances, ATC has a fair amount of latitude to give you what they want, or what you ask for. <S> The balance of responsbility between ATC and the pilot in command, is covered by 14 CFR 91.123 : <S> § 91.123 Compliance with ATC clearances and instructions. <S> (a) <S> When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory . <S> However, except in Class A airspace, a pilot may cancel an IFR flight plan if the operation is being conducted in VFR weather conditions. <S> When a pilot is uncertain of an ATC clearance, that pilot shall immediately request clarification from ATC. <S> (b) Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised. <S> (c) <S> Each pilot in command who, in an emergency, or in response to a traffic alert and collision avoidance system resolution advisory, deviates from an ATC clearance or instruction shall notify ATC of that deviation as soon as possible. <S> (d) <S> Each pilot in command who (though not deviating from a rule of this subpart) is given priority by ATC in an emergency, shall submit a detailed report of that emergency within 48 hours to the manager of that ATC facility, if requested by ATC. <S> (e) <S> Unless otherwise authorized by ATC, no person operating an aircraft may operate that aircraft according to any clearance or instruction that has been issued to the pilot of another aircraft for radar air traffic control purposes. <A> The ATC guys can't just do whatever they want. <S> They have to operate within guidelines - they will have an ATC handbook/manual etc, much like a pilot has a flight operations manual, which has been merticulously developed and approved by the authorities. <S> There are references in this manual as to when ATC can cancel speed restrictions, or deviate from the other usual procedures. <S> In most cases it will read something like "Speed restrictions under 10,000 feet may be cancelled in Class C airspace only, and if the controller is satisfied that no risk of LOSA (loss of separation assurance) exists". <S> Of course, everything goes out of the window in an emergency, however. <A> The speed limit of 250kts below 10,000 feet is mostly there to protect smaller aircraft and rotocraft. <S> For example, you might have a parachute jump plane flying around, and you don't want a Citation business jet bearing down on them (or the jumpers) at 400 knots: <S> At that speed you don't have much time to react: You look away for two seconds to drink your coffee and BAM! <S> There was a famous accident a couple of years ago in which a glider pilot was flying around Reno and a private jet flew right into him ( NTSB file LAX06FA277B ) . <S> That is exactly the kind of accident speed limits are supposed to mitigate. <S> If a pilot exceeds a speed limit, it really doesn't matter what ATC said, it is the pilot who is responsible. <S> If the FAA determines he did something reckless it makes no difference that some controller told him it was ok.
|
So in practical terms, ATC do have the ability to deviate from most of the usual procedures, but always within existing guidelines.
|
How is combustion flame maintained in the combustion chamber after igniters are switched off? During start phase of a jet engine, igniters in the combustion chamber create sparks to initiate combustion. As far I know, when the engine reaches self sustaining speed, igniters get turned off (this might be different (takes longer) in an Airliner due to FAA regulations during take off). My question is how do flames in the combustion chamber (or canisters) get sustained (like a candle) without igniters support? <Q> How does a candles flame sustain itself after you have lit it? <S> It stays lit by continually burning fuel. <S> The jet engine works the same way. <S> Air is constantly being supplied by the compressor and fuel is constantly being supplied by pumps. <S> This is fundamentally different to a traditional combustion engine you might be trying to reconcile this idea against. <S> In a 4-stroke internal combustion engine, for example, you have intake, compression, power and exhaust happening separately and you need spark plugs (or glow plugs) to ignite the fuel each cycle. <S> In a jet engine, however, instead of 4 independent cycles you have a constant flow of air through the engine. <S> Air comes in the front, is compressed by the N2 stage and fed continually into the hot section where the fire is constantly burning and then exhausts through the back of the engine. <S> Look at it like a propane barbecue grill or a gas stovetop -- you only need the ignitor to start the fire. <S> Once the fire is burning it stays that way until you turn off the flow of gas. <A> Another answer to add to caseys: <S> Flow speed near the fuel injectors is very slow, on the order of 30 m/s. <S> This is caused by a widening of the flow path between compressor exit and combustor called a diffusor or diffuser. <S> See here for more. <S> Radiation from the burning fuel-air mixture in the middle part of the combustor heats up the not-yet-burning mixture near the fuel injectors, which helps the fuel droplets to evaporate (this is a necessary step before combustion can start) and causes the mixture to be heated above its autoignition temperature . <S> Hence, this radiated heat will provide the fuel-air mixture with the needed activation energy for combustion. <S> Some combustors have small notches in their wall which create local turbulence and help to keep some of the burning fuel-air-mixture back, which helps to start ignition in the following flow. <S> These are called flame holders. <S> If all of the burning gas is washed out from the combustion chamber without igniting the following gas, the ignition process will stop. <S> This is called a flame-out . <S> The heat from the walls of the combustion chamber will not be enough to re-ignite the fuel-air mixture, because they are cooled by the airflow from the compressor and will rapidly cool down once the flame is blown out. <S> Note that this effect is used to extinguish burning oil or gas wells with dynamite . <A> To add to casey's post, the flame holder keeps the flame from getting blown out. <S> Its a part of the combustion chamber that allows the high pressure air from the final compression stage to swirl at a low speed to keep the flame front contained.
|
Once the fire is lit (by the ignitors) it is constantly burning.
|
Are those devices allowed on a flight which create their own WiFi signals? I am going from Canada to Mexico but I don't want to be dependent on in-flight entertainment. Thus I got seagate wireless plus so I can stream to my iPad. I couldn't find any policies I can use this device during flight or not. At very least I am trying to determine if it is worth asking the flight company? <Q> No, the rules are about any transmitter or receiver, regardless of whether it comes under the specific category of phone/tablet/laptop etc <S> If anything your device is worse as it transmits at a higher power and range than a receiver. <A> Airlines provide WiFi onboard and invite you to connect to it (for a fee). <S> To connect to WiFi you must have the ability to transmit (internet requires two way communications). <S> If your device is conforms to FCC power limits on the 2.4GHz bands (or whatever your particular jurisdictions regulatory body is) <S> then your device is no different than any other WiFi device on the plane. <S> They are all transmitters using the same maximum power. <S> If your airplane has WiFi onboard and let's you connect computers to it <S> then there is no technical problem with using your device. <S> Of course, if a crew member tells you to turn it off, remember you must comply. <A> The intention behind is to isolate the electronic devices of an airplane from electromagnetic radiation. <S> Modern airplanes are pretty well protected at the moment and they don't have any issue of isolation. <S> However, one thing that is key for authorities is flight safety. <S> So it is better to have stronger restrictions that making any mistake. <S> Finally, in any case those radiation devices should be turned off (or in airplane mode) <S> when flying in take-off or landing stages (so the wifi of the airplane does). <S> My recommendation <S> : ask the airline directly and get information about the airplane you are flying in.
|
So, in order to be able to use wifi on the airplane, you need to have, first the airplane modern enough and the airline shall be authorized by the authorities.
|
When is runway slope most important? Based on this other answer , a new question arose.When is runway slope most important, at take-off or at landing? Or is it equally important in both flight phases? <Q> I would argue that it is most important on takeoff. <S> The reason is that most planes require more distance for takeoff than for landing (partially due to higher weight). <S> Also, it is generally easier to abort a takeoff than a landing (when on the ground at least). <S> Both landing and takeoff distance calculations are performed (which should take slope into account) to ensure that there is sufficient distance for the aircraft. <S> However, in addition to aborting a takeoff being easier, more can go wrong in a landing. <S> Windshear or improper approach settings can cause an airplane to touch down later or faster, which risks an overrun. <S> During takeoff, the plane has until V1 (takeoff decision speed) to abort if any issues arise. <S> However, this certainly depends on conditions. <S> Aircraft condition, wind and runway surface condition can increase the distance needed for landing (or aborting a takeoff). <S> If reverse thrust is not available, there is a tailwind, and the runway is wet, that could change the situation. <A> I would rather land downhill than takeoff uphill because taking off uphill you have just one thing to get you off the ground: thrust (ok, maybe a little flaps helps in some airplanes). <S> On landing, I have a lot of things I can control: approach speed (slow), approach angle (steep), approach power (none), flaps (full), flaring before the threshold, aerodynamic braking with the elevator, pulling the flaps, full braking. <S> some of it is admittedly pretty gutsy, but you can stop even a slippery airplane quite quickly. <A> I am going to introduce another perspective. <S> We are talking about a road of 3km length with a potential difference of 1% (30m!!!!) <S> between the highest and lowest place. <S> Limitations of the slope in airports are not related to performance of the airplane, instead is a safety and visibility constrain. <S> So, either I am taking off or <S> I am landing I prefer in both to be running uphill where my airplane at the fastest speeds, so I will be able to see any object really far from where I am. <S> No matter the performance I lost. <S> Notice, that we need to consider also the visual range of the pilot (which is several meters above the road) which is not 3km for small objects, but, I prefer the safest condition: Uphill. <A> The only time you would worry about runway slope is insufficient runway. <S> So let's consider a runway overrun: <S> On takeoff, there's a period where you should no longer abort takeoff, as there is likely insufficient room for stopping. <S> That happens as the plane accelerates pass V1. <S> At that point the aircraft is quite some way down the runway travelling fast. <S> It's heavy as well. <S> If a late rejected take off is initiated, you'll likely hit the fence at a very high speed. <S> On landing, you plan to stop the plane anyway. <S> If things go awry, you can always step on the brakes. <S> Landing distances are never computed at max braking <S> so you got some room. <S> If you overrun, you'll hit at a much slower speed, since the plane is slowing down in the first place. <S> Therefore I'd argue it is more important on takeoff.
|
Runaways are always thought to have enough visibility for the pilot when trying to land of take-off.
|
Why did this Cirrus deploy the parachute while ditching over Pacific Ocean? In this incident near Hawaii , a Cirrus SR22 had fuel problems and deployed its airframe parachute . My question is why did the pilot deploy the parachute rather than perform a "normal" ditching procedure in the ocean? For reference, here's the video . <Q> Once your engine fails the airplane is the property of the insurance company, your only goal at that point should be to survive. <S> Using a whole-airframe chute increases your chances of survival whether over land or sea. <S> The things that kill people in forced landings of any kind are high-g deceleration and post crash fire. <S> A parachute decreases the chances of both as you have very low lateral speed and much less chance of fuel tank leaks. <S> A parachute also will increase the chance the airplane will remain upright, so escaping the aircraft will be much easier - very important in a water landing! <S> The only reason for a "normal" ditching procedure is that you have no other choice, using a parachute if you have one will almost always be the right option. <S> The only time I would consider otherwise is if I had enough altitude to glide to a safer emergency landing spot. <A> First, according to one operating handbook for the Cirrus <S> SR-22 (there are several versions out there), pulling the chute is the correct ditching procedure (CAPS is the parachute system): Ditching Radio ............................................ <S> Transmit (121.5 MHz) <S> MAYDAY giving location and intentions <S> Transponder........................................................... <S> SQUAWK 7700 <S> CAPS ............................................................................. <S> ACTIVATE <S> Airplane......................................................................... <S> EVACUATE Flotation Devices ............ <S> INFLATE WHEN CLEAR OF AIRPLANE <S> Second, the conditions were reported to be windy with high waves: <S> Weather conditions at the time of the rescue were seas of 9 to 12 feet and winds of 25 to 28 mph. <S> Those would be tough conditions for ditching in. <S> I've read several times that when light aircraft ditch, the pilot and passengers usually survive the impact but they often struggle to exit the aircraft successfully. <S> This article and video explain in detail how difficult it can be to exit an aircraft in the water, even in good conditions. <S> If the aircraft flips or cartwheels then exiting would be extremely tough and the rough sea would make it much worse. <S> Since the parachute lowers the aircraft straight down in a more or less level attitude, the chance of flipping over is greatly reduced. <S> The downside is that you no longer have control of where you touch down relative to the waves, so you might land just in front of one but that still seems like a good option compared to the risk of flipping the aircraft on impact. <A> Maybe pulling the chute is the normal ditching procedure for a cirrus with an airframe chute. <S> The splash down looks to be very gentle compared to a normal gliding ditch with fixed gear. <S> It's also less prone to pilot error; once you are dangling there is not much the pilot can mess up. <S> I imagine the checklist being something like: <S> pull chute when aircraft stabilizes open door put on life vest and prepare raft should plane roll and sink get out and on the raft <A> The odds of survival with the chute are currently at 100% (Per Cirrus) and the odds of surviving a ditching are much less. <S> The plane was lost in the Pacific either way. <S> The correct thing to do is pull the lever and ride it down, live to be a great pilot another day. <S> The real question is what did the pilot do wrong to end up in that situation? <A> The proper response to losing the engine would be to follow the emergency procedures checklist. <S> In that you will find it says to deploy the ballistic parachute. <S> While a better option, the ballistic parachute has its own drawbacks. <S> I recall when getting checked out in a Cirrus years ago by an approved training provider that I was told the impact with chute deployed can be up to 8 G's. <S> So I would say not 100% survivable. <S> Actually I know of a Cirrus that went down near Sanford Florida a few years back that deployed the chute and the occupants died.
|
If pulling the chute would mean landing in water or dangerous terrain but gliding would mean reaching land where a forced landing was reasonable I'd probably opt for gliding.
|
Why did most airliners have black noses in the 60's and 70's? Here are a couple of examples: <Q> Under the nose of modern airliners is weather radar that helps the crew to see and avoid hazardous weather conditions. <S> This is required by FAA CFR <S> §121.357 for transport category aircraft. <S> The radar signal would be blocked by the aluminum that makes up the rest of the fuselage, so the radome is made of a non-metallic material, generally a fiberglass composite. <S> These threads discuss the topic. <S> The last post in the first linked thread suggests that most paint needed lead to prevent fading and/or a zinc-based primer, which would interfere with the radar. <S> Black was one color that did not require these. <S> Modern paint has done away with these metal additives, allowing more color options without interfering with the radar. <S> The Museum of Flight claims that the black color is only to remind crews to not paint over the radome. <S> Painting over it would affect the radar signals. <S> According to this thread , the color of the radome affects the operation of the weather radar underneath. <S> They were painted black because it has the lowest reflectivity. <S> Modern radars are able to deal with different colors much better. <A> Because the nose of the plane is where the weather radar antenna is, and paint would interfere with the signals. <S> This is not just the 60's and 70's, and its not only on the nose. <S> Here's a brand new PC-12 with a radar dome (radome) on the right wing, painted black: <S> Inside of the radome is a radar array that can be tilted and panned using a control inside the cockpit: <S> This is the pilot's view inside the cockpit, which shows the knobs used to adjust the pan/tilt, range, and sensitivity: <S> And you can read a brochure about a particular aviation radar system here . <A> It is called a nose cone . <S> There can a several reasons (as mentioned here and here <S> ): <S> Aircraft used to be painted with a lead-based paint, which is unsuitable for radomes. <S> Instead, they had a rubber coating. <S> Nowadays, the paint used (epoxy on military planes, I believe) won't affect the radar. <S> It's as much a fashion statement as anything else <S> It started out as an anti-glare panel. <S> Even today, you can find some military aircraft with a darker nose cone.
|
The fuselage within pilot's view is painted dark and of matte finish to reduce the chance of any glare that might obscure pilot's vision.
|
What is the MEL (minimum equipment list)? What is a minimum equipment list for an aircraft? How are MEL and MMEL related? Who creates the list, and how do they decide what is on it? <Q> As mentioned here : A minimum equipment list is a list of equipment that must be installed and operable for the aircraft to be considered airworthy. <S> It is aircraft-specific and spells out which pieces of equipment may be inoperable while maintaining airworthiness. <S> If something is found to be inoperative, the pilot goes to the MEL, finds the entry for that item, and determines if the airplane must be grounded until that piece of equipment is fixed. <S> A Master minimum equipment list is: An MEL for a specific aircraft originates from a master minimum equipment list (MMEL). <S> The MMEL is a list of all equipment on an aircraft type; it details which equipment is allowed to be inoperative without grounding the aircraft. <S> (Think of a MMEL as a general, broader <S> MEL.) <S> FAA publishes MMELs by manufactures. <A> The MEL is NOT a list of equipment that must be installed and operable for the aircraft to be considered airworthy. <S> The correct definition is: <S> The MEL is a list of aircraft equipment that can be inoperable PRIOR to dispatch. <S> MEL items are only applicable before your flight is dispatched. <S> Once you are in the air you need to consult the aircraft QRH. <A> The MMEL (Master Minimum Equipment List) is generic across a type of aircraft. <S> e.g. Cessna Citation CE-500, CE-550, CE-560. <S> A single MMEL is published by Cessna to cover all of these models from the factory (Master). <S> A MMEL can not, and does not, take into account differences that may occur during upgrades and modifications, nor differences that may be present within specific airframe serial numbers. <S> In a fleet situation of like type airframes with minor differences, a MEL can spell out which serial numbers are applicable for a given item. <S> Once a MEL is approved, it becomes a 'bible' for dispatch or no-dispatch. <S> A MMEL is not enforceable, as it is not minded by a LOA, but is more guidance in determining whether dispatch is recommended. <S> A MEL can be more restrictive than a MMEL, but not less restrictive. <S> By the definition of 'airworthy'; therefore, the MEL may ground a plane for certain operations, but does not make the aircraft 'unairworthy' for other operations. <S> e.g. <S> An operation operating an aircraft under a Part 135 certificate with a more restrictive MEL approved for the 135 may ground the plane for 135 operations, yet the owner may operate the same airframe under Part 91 using their MMEL if allowed. <S> The FAA would love all jets to adhere to at least a MMEL, and push operators to get a MEL approved through the LOA (Letter of Authorization) process.
|
A MEL (Minimum Equipment List) is a 'custom' document generated and approved for a specific airframe serial number, or a group of aircraft that are identical (fleet).
|
Why do we use pylons to mount the engines on jetliners? This question focus on jet airliners. The De Havilland Comet's engine were mounted inside the wing, the Concorde's engines were mounted underwing (as many jet engines) but without pylon. It seems jet airliners' engines are now mounted on pylon. That assumption goes wherever the engine is mounted ( underwing or at the rear of the aircraft). What are the advantages of doing so (aerodynamic, maintenance, safety,...)? Is there some drawback (must be minimal as this design is dominant)? Note: I don't want discussion about where to mount engine (underwing as for the B747, overwing as for the VFW-Fokker 614, at the rear as for the MD-80, ...), I'm curious about why we use pylons for all this designs. <Q> Engine placement was a tricky question when jets were introduced, and much has been learned since then. <S> The initial idea was to mount them inside the fuselage or wing root. <S> When they grew too big, they were closely mounted to the wing ("underslung" position, like in the Me-262 , the Il-28 or the early Boeing 737 ). <S> However, the underslung position has two disadvantages: <S> More of the leading and trailing edges is obstructed, blocking space that would otherwise be used for slats and flaps. <S> Consequently, an underslung position reduces maximum lift. <S> The center of gravity of the engine is too far back. <S> Moving it more forward helps to place the center of gravity of the wing ahead of its elastic line. <S> Bending will now create an opposing inertial moment, which is very helpful to dampen flutter. <S> Starting to move the engine downwards away from the wing initially increases drag, because now a narrow slot opens between both with a tendency to separated flow. <S> Only when the engine is moved downwards enough, the drag of the wing-engine arrangement reaches its minimum. <S> This placement was chosen in the next generation of jets like the <S> B-52 or the Boeing 707 . <S> Moving it still further down makes the pylon longer and thus increases the total drag again. <S> The big diameters of modern high-bypass ratio engines make it impractical to move it down enough to reach the drag minimum, but by moving it forward, the engine can again be lifted up, so a shorter landing gear becomes possible. <S> Vortex generators are added if that pesky separation between engine and nacelle cannot be avoided. <A> Mounting the engine on a pylon rather than integral to the wing, allows the aircraft to accept different engine types (eg, Rolls Royce, P&W, or GE) or different sizes of engines. <S> For example the 757 had three different engines , each made by a different manufacturer: <S> Launch customers Eastern Air Lines and British Airways selected the RB211-535C turbofan built by Rolls-Royce, which was capable of 37,400 pounds-force (166 kN) of thrust.[19] <S> This marked the first time that a Boeing airliner was launched with engines produced outside the U.S.[8] <S> Domestic manufacturer Pratt & Whitney subsequently offered the 38,200 pounds-force (170 kN) thrust PW2037,[19] which Delta Air Lines launched with an order for 60 aircraft in November 1980.[8][20] <S> General Electric also offered its CF6-32 engine early in the program, but eventually abandoned its involvement due to insufficient demand. <S> The pylon not only mounts the engine, but allows the different engine designs to adapt to the airframe. <S> Secondly, by disassociating the airframe from the engine, the engine can be repaired and replaced without disassembling the wing . <A> The passenger jet engine mounts (pylons) are designed to break away due to excessive vibration (a type of engine failure) because you would rather drop an engine than have your wing break off and drop like a brick. <A> The foremost reason is, the engine is isolated from critical structural components in the wing, enhancing safety. <S> If there were a fire, the fire would not be likely to burn the wing off since the airstream would ensure the flames avoided the wing, in which the fuel is housed in modern jet designs. <S> Also, if the engine were to explode in an uncontained failure, the shrapnel would be less likely to ignite a fuel source, damage a wing spar, or damage flight control surfaces. <S> The hanging pod design surrounding the compressor and turbine sections helps contain catastrophic failures, and the pod design also enables bypass air to envelop the engine on all sides, an important enhancement for hot-section cooling and fuel economy. <S> Additionally, a pylon-mounted engine does not interfere with the airflow over and under the wing to the same degree as a wing-integral design would. <S> Another less important advantage is, the engine is more accessible for maintenance purposes. <S> But a disadvantage is the engine is more vulnerable to picking up foreign object damage, being closer to the ground. <A>
|
The real answer: pylons make engine maintenance easier and are a more practical solution for current high bypass turbofan engines.
|
Have there been any 'proper' field trials of Automated Air Traffic Control? Have there been any 'proper' field trials of Automated Air Traffic Control? Specifically, something that has been tested on larger aircraft and has come beyond the drawing board. By automated I'm implying that all decisions on movements are made by computers and instructions would be for instance transmitted digitally to the cockpit. <Q> No Short answer, <S> but there has never been anything resembling a "proper" trial. <A> There have been many trials involving large aircraft and various levels of ATC automation. <S> However these trials do never involve more than a handful of aircraft. <S> And always with a human Air Traffic Controller tightly in the loop for safety reasons. <S> And never were all decisions made by the automation system. <S> Progress comes in small steps. <A> I suspect one of the bigger issues with automated ATC is you will always need human controllers to be there to take over when the automated system fails. <S> Moreover, since the job of an ATC controller is a difficult one that requires a great deal of mental dexterity to translate a two dimensional display or moving object information into a mental picture of a three dimensional airspace, the individual really needs to be active regularly enough to keep those skills sharp. <S> There is no doubt a computer can monitor and extrapolate how traffic is moving relative to one another far better than a human can, but the whole communication with a human thing is another story. <S> It might work great as long as everything was operating routinely, but odd things happen quickly. <S> As such, you sort of want it automated <S> but at the same time... you don't. <S> I rather suspect, and hope, that instead of going down some fully-automated route, the tools presented to the human ATC will improve instead. <S> How that blends into moves to use pilotless aircraft.. <S> I have no idea.
|
There have been a few small scale, limited and tightly controlled trials, but nothing over any significant time frame, involving a significant number of aircraft, or even involving aircraft in "normal" use.
|
Do we have a unit to measure turbulence? Do airplanes have any way to quantify the turbulence like if shakes are there or the some kind of air drift is happening every parameter of these have some units but do collectively there is any such unit which can quantify the turbulence? <Q> EDR can be calculated from available onboard measurements, however it is not yet common for aircraft to have software to calculate the EDR. <S> Originally it was thought to have EDR reported over ADS-B , but it did not become a part of the current specifications. <S> It might be in the next ADS-B version. <S> NASA Langley paper World Meteorological Organization (WMO) <S> presentation <A> Turbulence is described using the following qualitative descriptions [ Source ]: <S> Informally, you can use a g-meter to quantify turbulence, at least in the up-down direction, but I don't know of any particular values that equate to various types of turbulence <A> I think you are asking two questions in a single way. <S> I understood that you would like to know <S> firstly is there is a physical unit that could give you quantifyable information about airplane turbulence and, <S> on top, you are asking if, having this unit, is possible to quantify turbulence in flight. <S> For the first one, you already have nice answer about them. <S> You can quantify by using EDR or some other similar units. <S> To the second part of the question, can I actually in flight measure it? <S> , the answer is more complicated. <S> Is possible to measure the turbulence once the airplane is affected by it using its effect on the airplane. <S> However, to the question, can I measure the turbulence before airplane flies over it? <S> that's more complicated, and there are some R&T projects trying to investigate LASER based detection both short range and long range (30km). <S> There is an European project called DELICAT working on this topic.
|
Turbulence can be quantitatively expressed as Eddy Dissipation Rate (EDR).
|
What is the minimum thrust needed to takeoff? In passenger airplane how much thrust is required to takeoff? What factors does it depend on? <Q> This is quite a bit higher than the minimum flight speed, so you should add something to quicken the acceleration to this point. <S> Also, you want to climb eventually, so you better add some more thrust. <S> Normally, the static thrust of an airliner is at least a quarter of its weight. <S> If the airliner is empty, this can become as much as half of the weight. <S> One reason is altitude capability: Since thrust goes down with the density of air, the static thrust in the cruise altitude is only a quarter of sea level thrust. <S> The thrust of a modern high-bypass-ratio engine drops with speed, so at cruise speed and altitude, thrust is roughly a sixth of sea level static. <S> The second reason is safety: <S> The take-off should be continued even after one engine fails in the late acceleration phase. <S> Now a normally two-engined plane has only half as much thrust available and should still get into the air, so it doesn't crash into whatever follows at the end of the runway. <S> The thrust needed to sustain flight is about 1/18 of aircraft weight, and if you factor in the multiples given above, you will notice that if the aircraft can fly at full thrust in cruise, this fits nicely with a static sea level thrust force equivalent to one third of its weight force. <S> The factors for take-off thrust are: Runway length: <S> Short runways need more excess thrust for faster acceleration. <S> Runway elevation: Higher places have less dense air, so more speed is needed to get airborne, and less thrust is available from the engines than at sea level. <S> Runway slope. <S> Taking off downhill is equivalent to having a little extra thrust. <S> Air temperature: <S> Colder air is denser, so minimum speed is lower and the engines develop more thrust. <S> Wind speed: A headwind is equivalent to starting the takeoff run at this speed. <S> Minimum flight speed: A low wing loading and low-drag flap settings reduce the speed at which the aircraft can take off. <A> The amount of thrust necessary is the force required to accelerate the aircraft to take off speed, a speed which allows the wings to generate enough lift to sustain the aircraft in the air. <S> Factors include aircraft weight runway condition (length, slope, dry/wet) flaps configuration head wind component <S> If it's a multi-engine aircraft, the ability to safely get airborne in the event of a single engine failure is considered as well. <S> If by "amount of thrust", you mean the acceleration force: <S> engine power ranges from 160hp on small propeller planes to thousands of pounds in turbine jets (Boeing 777's engine is rated at 417kN). <S> In most GA planes, takeoff power = full power. <S> In larger aircrafts, typically it is slightly below full power to save engine wear. <S> Note that "thrust" is not used to get an airplane off the ground. <S> " <S> Lift" is used to get it airborne and counteract the "weight". <S> " <S> Thrust" is produced by the engine(s) to propel the plane forward, "lift" is created by the wings. <A> It all comes down to Newton's second law of motion in that: $$F= m <S> \cdot a$$ <S> The trust required for a 70 m/sec. <S> 10.000 kilos takeoff speed and weight with an acceleration of 2g is: 20 Kilo Newtons, it will take 35 seconds and 1225 meters of runway to become airborne .At <S> the moment airplane manufacturers have to trade off Power and Speed to the best fuel economy. <S> but with propellers a max speed is about 662 K hr ( SAAV 2000 ) and jets with a optimun speed is 880 k hrs. <S> Both do not travel at the optimun speed for ANY airplane of around 700 kms per hour <S> wich is where induced drag and atatic drag are at their lowest so a propeller airplane is slow and a jet is fast and the penalty is fuel consuption because the jet have travel at the speed of combustion in the engines and propellers can not be made bigger than they are now (speed of sound limits their size at the tips) <A> Notwithstanding exceptions and certain details the operator can decide about, generally the minimum thrust required to satisfy EASA (and <S> FAA) regulations on takeoff performance for civilian jet aircraft is that which allows for a given weight, aircraft configuration, runway, and set of environmental conditions to Accelerate to the value of V1 speed pertinent to that specifictakeoff with all engines operating <S> Either reject the takeoff from V1 speed with either all engines operating or one engine inoperative within the allowed distance for the stop case or Continue the takeoff from V1 speed with one engine inoperative,accelerating to VR and V2 speeds pertinent to that specific takeoffwithin the allowed distance for the takeoff case Climb out from the runway at V2 speed while meeting a minimum climbgradient defined in the regulations (depending on the number ofengines) <S> Clear all obstacles under the takeoff flight path by a certainpredetermined margin Reach a minimum height for flap retraction or attain cleanconfiguration and associated speed within the maximum time limit forengine operation at takeoff thrust (usually either 5 or 10 minutes) <S> This is a rather simplified, condensed version of various paragraphs in EASA CS 25 (Certification Specification for Large Aircraft) and EASA Air Operations regulations , chapter POL (Performance and Operating Limitations - <S> e.g. CAT.POL.A.205 details takeoff distance requirements). <S> For more details, I'm afraid that actually reading the regs is as good as it gets...
|
You need at least enough thrust to keep the airplane flying at the speed of minimum drag.
|
Why aren't there more helicopter aerobatics at airshows? I enjoy watching RC helicopter stunts like these . Many RC pilots are very talented, executing barrel rolls and other inversions. How come we don't see these kind of displays at airshows? <Q> There just aren't many helicopter aerobatic pilots around. <S> There is one <S> I know of: Chuck Aaron <S> he can do the typical maneuvers in a specially modified helicopter. <A> First off: I'm not a pilot. <S> I believe there are two additional issues here: <S> There is no pilot in the RC helicopter. <S> The forces exerted in some of those maneuvers look pretty extreme, I highly doubt even the most well-trained aerobatics pilot/astronaut/fighter jock would be conscious longer than about 2 minutes into the video you posted. <S> I'm not even sure if they would be able to survive that. <S> Scale. <S> All sorts of weird things happen when you scale complex systems up or down. <S> (A famous example is the square-cube law: when you scale a structure up linearly, it's area scales as a square, and its volume (and thus weight) scales as a cube. <S> So, an ant that is 100 times bigger will have feet that are 10000 times bigger but will have to support a weight that is 1000000 times bigger.) <S> For example, the airframe of the RC helicopter is much stronger in relation to its size than it is on a real helicopter. <S> Also, RC models (not just helicopters) are typically ridiculously overmotorized compared to their real-life counterparts. <A> First off, the reasons you don't see real helicopters performing literally like that model are that it's impossible to get anything like that power-to-weight ratio on a full-size machine and also because the pilot would black out from the ridiculous G's being pulled. <S> For example, the British Army Lynx display includes rolls, loops and even back-flips. <S> However, I distinctly remember commentary at an airshow <S> I attended saying that, when the Lynx is retired fairly soon, its replacement won't be certified for any kind of acrobatics. <A> As ratchet freak mentioned, it is simply not common. <S> Why, you ask? <S> Airplane aerobatics? <S> Calculated, practiced, somewhat risky, entertaining. <S> Helicopter aerobatics? <S> Closer to a death wish than airplane aerobatics. <S> The aerodynamics of helicopters are more complex (think fragile). <S> There aren't as many people willing to do it.
|
As for why you don't see a whole lot of... less ambitious acrobatic flying in helicopters, it's possible that certification is an issue.
|
What would happen to the rudder on an A320 if both FAC systems failed? What would happen to the rudder of an A320 if both Flight Augmentation Computer (FAC) systems completely failed during mid-flight? Would the auto pilot immediately pass control back to the pilots or if they failed would that be it? Would it be impossible for the cockpit to communicate with the mechanisms which control the rudder or is manual operation possible in an A320? Also, I know this maybe a more difficult/impossible questions but what would cause the malfunction of one of the FAC computers? Are there any likely scenarios or previous cases? <Q> The A320 has a mechanical link from the rudder pedals to the hydraulic rudder actuators. <S> The elevator trim wheels are also mechanically connected, so rudimentary control of the aircraft remains even in the event of a total electronic failure, as long as there's hydraulic power. <A> The Flight Augmentation (FAC) performs the following functions: <S> Yaw damper Rudder travel limiting Monitoring of the flight envelope and computation of maneuvering speed Yaw autopilot order Bite fuction of the AFS <S> The trim actuator, the yaw damper servoactuators and the travel limitation unit are normally controlled by the flight Augmentation Computer (FAC 1) and FAC 2 being in standby. <S> The rudders are controlled either mechanically from the pedals or electrically when the auto pilot is engaged. <S> Therefore if both FACs fail, the rudder control remains unaffected. <S> However the autopilot is no longer available. <A> Only the Rudder has a mechanical link which remains functionnal enough even with electrical commands failure. <S> Landing with it together with engine control only has been tried during certifications.
|
Computer-generated rudder commands for yaw damping and turn coordination are added to the mechanical signal from the rudder pedals, but in the event of a two-sided computer failure the rudder can still be controlled.
|
Can spatial disorientation in low visibility situations lead a pilot to fly upside down? In this comment it's mentioned that pilots in instrument conditions may wind up in a situation where they're inverted due to spatial disorientation , and be completely unaware of it until they fly out of the cloud. Is that really something that can happen so easily? <Q> The short answer is "Yes", if the pilot is not properly trained, doesn't trust their instruments, or has an instrumentation failure. <S> Without a visual reference (such as the real horizon or artificial horizon) it's very easy for a pilot to place their aircraft in an "unusual attitude" -- something other than the expected straight-and-level flight or commanded turn. <S> As humans we naturally rely on our inner ear and sense of balance to tell us what's "up" or "down", but in a moving aircraft you can move through a whole range of attitudes in "1G maneuvers" (where your body thinks down is where your seat is). <S> Little micro-movements we unconsciously make on the controls (or larger movements we may make consciously in response to turbulence or other perceved disturbances in the aircraft's attitude) based on what our ears and butts are telling us will eventually get us into trouble. <S> It's so easy that often instructors will have students create their own unusual attitudes in training by having the student close their eyes and simply try to fly straight and level - within a few minutes at most the student will invariably no longer be in level flight. <S> There's an exercise you can do on the ground to illustrate how imperfect your sense of balance and direction is, but it requires a large, flat, open area. <S> We'll use an American Football field for this example: <S> Stand on one of the goal lines <S> Have a friend stand at the 50 yard line (about 45 meters away) <S> Close your eyes or put on a blindfold, count to ten, and walk directly toward your friend Stop when you reach your friend (or your friend yells "STOP" because you're about to walk into a goal post) <S> Most people will not make it to their friend on the 50 yard line, because without a visual reference it's very hard to walk a straight line: You will veer off one way or the other, and some folks will even manage to walk in a complete circle (which is what eventually tends to happen over a large enough distance). <S> The same principles apply to flight, except there's a third dimension (vertical) to contend with. <A> Yes, definitely. <S> This is from an NTSB accident report : During the right turn, the pilot stated that he looked to his right to cross check the GPS and set up the autopilot for a coupled approach. <S> He felt the airplane start to accelerate rapidly, and he looked back to the Primary Flight Display (PFD) which was “showing all brown with no sky and 6-7 chevrons, indicating a severe unusual attitude.” <S> He tried to correct the unusual attitude, but said that he had severe vertigo, and was unable to regain control of the airplane. <S> He elected to deploy the ballistic recovery parachute, and the aircraft impacted terrain in a nose low attitude in a creek bed. <S> The roll wasn't fully inverted, but it was extreme (120 degrees to the left): <S> The downloaded data showed that, just prior to the accident, the airplane went through a series pitch and roll oscillations, with maximum pitch values of approximately 26 degrees nose up, and 75 degrees nose down. <S> The airplane reached maximum roll values of approximately 83 degrees right wing down, and 120 degrees left wing down. <S> The reasons why this can happen so easily have been discussed and commented in detail in this question . <A> Yes. <S> Remember that once you get into a weird position, like upside down, you may be turning at the same time, creating a false gravity, so it does not feel like you are upside down. <S> Usually you just feel "cockeyed", and if you try to adjust based on that "feeling", you will make the WRONG input which will make the situation worse. <S> If you strap yourself inside a ball in an amusement park and get turned upside down, even then it can be difficult to tell exactly what is going on. <S> Many pilots have difficulty trusting their instruments and have to be trained to do so very strictly. <S> When I was put "under the hood" for the first time, my instructor told me "you will go into a spin". <S> I said "no I will not". <S> He said, "Yes you will, everybody does the first time." <S> As a matter of fact I kept the plane straight and level and did not go into a spin, but I was an exceptional case, 95% of students will start spinning the aircraft uncontrollably if they cannot see the horizon. <S> JFK, Jr. was killed that way. <S> Let me just say, that first time under the hood I was sweating bullets and focusing my mind like I was trying to play speed chess against Bobby Fischer. <S> Flying by instrument is INSANELY hard, if you have not trained on it for hours and hours. <S> You have 5 different needles that you have to keep lined up at the same time. <S> Even experienced pilots find manual instrument flying grueling and mentally taxing (thank god for autopilot). <A> Yes, very easily... <S> Although 'sideways, nose down and at 200 knots into the ground before becoming a massive fireball' is more common <S> If it's only a short period they may just find themselves coming out of the other side of the cloud at a completely different attitude than they went in (and, likely, altitude too), but with anything more than just a quick cloud, it can be far more serious. <S> Pilots without an instrument license have something like a 3 minute life expectancy once they get into instrument conditions.
|
So yes, it's absolutely possible for the aircraft to end up in an extreme attitude very quickly and easily: in this case the pilot just looked away to set the autopilot.
|
How Earth's rotation affect flight times? How much does Earth's rotation affect flight times in going East or West, and how could you calculate if zero winds? <Q> It does not affect as much as one would think. <S> The atmosphere moves along with Earth's rotation. <S> An airplane taking off from one place on Earth has to move through the atmosphere which is moving with Earth. <S> Now you may ask when does it take longer when we travel from Western Europe to Eastern USA, compared to USA to Europe? <S> That depends on Jet Stream : <S> Jet streams are fast flowing, narrow air currents found in the atmosphere of ... Earth. <S> Many air routes take advantage of jet streams, as you can see as follows: <S> Pilots know about the jet streams and will try to gain benefit of them. <S> Recently, there were some news that a flight from New York to London traveled faster than expected because it was in jet stream (details here and here ). <S> If you want to know why Earth's atmosphere moves with it, please see this . <S> There is a similar question on Physics. <S> SE . <A> It affects flight time the same way that it affects driving time. <S> Cars measure their speed over the ground based on wheel speed. <S> Airplanes can measure their speed over the ground using things like GPS. <S> Either way, it's referenced to the ground. <S> Technically the ground is moving, but it's not perceptible to us <S> and we still would say zero speed means not moving over the ground. <S> Airplanes primarily measure their speed through the air (airspeed), and the air tends to move with the ground, so the situation is the same. <S> If the air is not moving the same as the ground, it's called wind, which is the primary influence on flight time . <S> Wind is influenced by the earth's rotation, but the rotation doesn't directly influence flight time. <A> This is a physics question, not an aviation question, and might better be posed on Physics StackExchange. <S> Simply put, the question has an infinite number of answers! <S> Let me explain. <S> When you are stationary in a helicopter, waiting to take off, with reference to an observer also standing next to the helicopter, your speed is 0. <S> But with reference to an observer in a static point in space whose frame of reference is the centre of the earth, you are already moving at about 1040MPH. <S> The surface of the earth is also moving at 1040MPH. <S> (BTW, it is itself impossible to define a static point in space since all of space is moving.) <S> The atmosphere you are about to fly in (assuming zero wind) is also moving at the same speed. <S> If its speed was zero, with reference to the stationary observer in space, then the 1040MPH wind might make flying a little difficult. <S> You lift into the hover. <S> Now to both observers, you are still doing the same speed because speed is a scalar and you have added no force to change your horizontal speed. <S> To the observer standing near the helicopter, the earth, the helicopter and the air it is flying in are all moving at 0 speed. <S> To the observer in space, they are all moving at 1040MPH. <S> You now fly West at 100MPH. <S> To the observer standing on the earth, your speed is now 100MPH <S> but to the observer in space, your speed is now 940MPH. <S> You have slowed down! <S> By picking any arbitrary observer, at any point in space, and doing any speed you choose, you can see that there are an infinite number of answers to the question. <S> Only by asking the question with reference to a specific observer, can you answer the question.
|
If you ignore wind and side effects such as the Coriolis effect, the earths rotation has no effect on your journey time since you and the craft you are in must move at the same speed within the same frame of reference, relative to any given observer, together.
|
Would TCAS ever issue a "climb, climb!" RA that would stall a jet with a low airspeed? As a for instance, let's say there are 2 jets going at low airspeeds (close to $V_S$) that get too close to eachother and a TCAS Resolution Advisory callout is announced. Would TCAS issue an RA to order one of the jets to climb, resulting in loss of airspeed and a stall? <Q> The FAA publishes Advisory Circular 20-151A , which says in section 2-17(a): <S> Because TCAS II can only accept a limited number of inputs related to airplane performance, it’s not possible to automatically inhibit CLIMB and INCREASE CLIMB RAs in all cases where it may be appropriate to <S> inhibit such RAs. <S> In these cases, TCAS II may command maneuvers that may significantly reduce stall margins or result in stall warning <A> Or, (in the case of slow flight at approach speeds) to execute a go-around from an approach to land. <S> An aircraft can only be stalled if the critical angle of attack is exceeded. <S> A TCAS alert to climb is just that, it does not command the pilot to do anything other than climb to a safe altitude. <S> It tells the pilot where to go, but <S> not how to get there. <S> Initiating a climb at low speed does not automatically result in a stall as the question would seem to imply. <S> Proper pilot technique is to add power and adjust attitude to maintain safe airspeed and AOA. <S> The aircraft can only be stalled if the pilot pitches the nose up, fails to add sufficient power in the climb, allows airspeed to decay, and holds the attitude until a stall is reached. <S> So, the short answer is no. <A> I think this is possible. <S> TCAS generates Resolution Advisories based on various factors, and two aircraft equipped with TCAS transponders then coordinate their RAs. <S> Each aircraft knows only the bearing, altitude, and distance of the other aircraft; it gets its data from Mode S transponders, which don't send things like stall speed or maximum climb/descent rate. <S> That's all that the basic TCAS algorithm uses. <S> It doesn't necessarily even know its own plane's performance information. <S> Separate from the basic RA system, an installation can be configured to not issue "Climb" or "Increase Climb" RAs under certain circumstances (each TCAS RA is sufficient to avoid a collision if the other aircraft does nothing, so <S> "Maintain Climb" or "Reduce Descent" or "Do Not Descend" may be enough). <S> This doesn't change the general sense of an RA (climb/descend), but rather modifies the actual RA issued to its own aircrew. <S> However, it does not have to be configured in such a way, and the configuration won't necessarily catch all stall situations. <S> So a TCAS system is certainly capable of issuing an RA that will stall your plane.
|
There is no more risk of stalling an aircraft from a TCAS alert than from being instructed verbally by ATC to climb to a higher altitude for traffic avoidance.
|
Is it possible to do a barrel roll in a large aircraft like a B737? Can the bigger planes like B737 do barrel rolling kind of stunts like fighter jets do? I'm sure if it's full of passengers or cargo it would be very difficult and dangerous, but is it possible with an empty aircraft? I remember an All Nippon Airways incident where the co-pilot did a 131 deg roll by mistake but I don't know if a complete barrel roll is actually possible in large planes? <Q> This aircraft was the prototype for the Model 707. <S> When a barrel roll maneuver is properly performed the aircraft remains in a positive-G state, so no "inverted flight" is experienced by the aircraft. <S> According to the International Aerobatic Club , The Barrel roll is a combination between a loop and a roll. <S> You complete one loop while completing one roll at the same time. <S> The flight path during a barrel roll has the shape of a horizontal cork screw. <S> Imagine a big barrel, with the airplanes wheels rolling along the inside of the barrel in a cork screw path. <S> During a barrel roll, the pilot always experiences positive Gs. <S> The maximum is about 2.5 to 3 G. <S> The minimum about 0.5 G. <A> Yes, and its happened at least once in a -80 <S> which eventually became the 707. <S> It became so legendary that rumor has it <S> Boeing Chief Test Pilot John Cashman stated that just before he piloted the maiden flight of the Boeing 777 on June 12, 1994, his last instructions from then-Boeing President Phil Condit were "No rolls." <A> We experienced this possibility using a simulator on a 747/400.You have to take a very high angle at the beginning like 25° nose up to avoid exiting with an important nose down and overspeed. <S> Of course doing it with passenger is stricly forbiden. <A> Here is a video of a stolen Q400 Dash-8 doing a barrel roll. <S> That's not quite as large as a B737, but I think it's close enough for the purposes of the question, especially given <S> it was accomplished by an amateur. <S> It's fair to assume that a trained pilot could do at least as well in a much larger plane--if they were willing to risk their job/license. <A> Yes it is possible. <S> It happen in a Brazilian plane hijack in September 1988 on flight VSP375 from Vasp flight company. . <S> The plane was a Boeing 737-317 (# 23176, serial #Boeing 1213, Brazilian register PP-SNT). <S> The hijacker wanted to throw the plane on Brazilian president official home , the pilot tried the maneuver and succeed with 105 passengers onboard.
|
Yes, it is possible. Yes, it has been done before in an even larger aircraft, the Boeing 367-80, very famously by "Tex" Johnston on August 7, 1955 .
|
Why are geodesic airframes no longer produced? Why are geodesic airframes no longer produced? Do they cost more than conventional structures? Are they not as strong as conventional structures? I assume it is insufficient cost benefit ratio, but how does that work out? Wellingtons under construction. Photo: Royal Air Force <Q> Geodesic (sometimes also spelled geodetic) <S> designs were used in aviation as early as 1909, in the Schütte-Lanz SL1 airship. <S> It had a wooden structure with fabric covering, and Professor Johann Schütte, the scientific head of this design, used the most efficient method conceivable. <S> However, planning the shape of all structural members was an enormous amount of work, and stretching an existing ship by inserting a new section was almost impossible. <S> For those reasons, the late Schütte-Lanz airships used aluminum frames with conventional design, just like Zeppelin did from the beginning. <S> Diagonal wire bracing was used to take up shear loads. <S> This is helpful when the aerodynamic covering is not stiff enough to contribute any shear stiffness, as in the case of fabric covering. <S> However, when the skin is made from the same material as the frame, it can carry shear loads and a geodesic frame would not improve matters. <S> Now it is better to carry longitudinal loads in longerons and shear in the skin. <S> But geodesic constructions are not dead. <S> CAD makes the design effort manageable, and in some cases they give a weight advantage. <S> Look at the casing of the EJ200 engine : It uses a geodesic reinforcement to make the casing light and strong and to prevent harmful vibrations. <S> In the end, a jet engine casing is a big pressure vessel and needs to be strong, stiff and light. <S> photo by Julian Herzog, CC-BY <A> The switch from internal frames to structural skin airframes -- called monocoque construction -- is fairly well covered in Wikipedia : <S> Early aircraft were constructed using internal frames, typically of wood or steel tubing, which were then covered (or skinned) with fabric 3 such as irish linen or cotton. <S> The skin added nothing to the structural strength of the airframe and was essentially dead weight beyond providing a smooth sealed surface. <S> By thinking of the airframe as a whole, and not just the sum of its parts, it made sense to adopt a monocoque structure <S> and it did not take long for various companies to adopt practices from the boat industry such as laminating thin strips of wood <S> That being said, we are still producing tube and fabric airplanes, particularly taildraggers based on classic designs, such as this American Champion Citabria and this Super Cub : <A> It started when the usual way of building was a steel-tube frame, with wooden formers attached to carry the skin. <S> Early geodetic planes were still fabric covered, but the entire airframe structure was now in the skin, leaving the interior open for payload like people or ordnance. <S> It was much lighter and stronger, though patented and many builders simply don't want to license-build as much of their plane from somebody elses' ideas. <S> Once metal skins were being used, it wasn't the only monocoque option, though it was still superior to the usual orthogonal structures. <S> Still more expensive though. <S> "Geodesic" should refer to the field of mathematics itself. <S> Geodetic applications of it work for space-frame structures or mapping a globe, etc. <A> Geodesic airframes are useful for purpose-built crop dusters, built from 4130 stainless steel tubes. <S> The chemicals on board could easily react with aluminium, which is still used for skin panels but not as a structural member: the skin plates are only for covering, not for taking any of the prime loads. <S> The construction method is one of the reasons why they look unlike any other plane, with the angular cockpit shape and all. <S> Other than that, monocoque construction has completely taken over from geodesic frame construction - when the skin plates are the main load bearers the airframe is lighter.
|
Geodesic frames are good in transferring both bending and shear loads.
|
Why don't airliners have a navigation GPS as back up in case of a pitot tube malfunction? Why don't airliners have a navigation GPS as "back up" in case of a pitot tube malfunction? Aeropero 603 and Air France 447 plus many other im sure, could have been saved if these aircrafts would have had a simple Navigation GPS as a plan B. The GPS could have given the pilot the basic information needed to keep flying instead of leaving them confused about what the instruments were showing due to the blocked pitot tubes. having reliable information of ground speed, heading and altitude would have helped the pilots recognize the situation they were in, which was caused by Pitot tubes blockage. Most private pilots now use GPS why not the big airliners?There is many blogs about why airliners do not have GPS tracking so the planes could be found after a crash, but none talking about why GPS is not use to help prevent some of those crashes. <Q> In AF 447, the primary consequence of the blocked pitot tubes was that the flight envelope protection system couldn't do its job properly and therefore automatically disengaged together with the autopilot. <S> The subsequent crash was caused by the pilots' confusion and failure to realize which consequences this had for the aircraft's reaction to their control inputs. <S> However, what this system needs to function is not something a GPS system can possibly provide. <S> GPS knows how fast the aircraft is moving relative to the earth , but for flight envelope protection you need to know how fast the aircraft is moving relative to the surrounding air , which GPS doesn't have any way of knowing. <S> The differences between these values is caused by wind and can be pretty large. <S> It would be a recipe for disaster to let the computer limit what the pilot can do based on an arbitrary assumption that there's no wind. <S> (And, as Terry comments, there's an additional difference caused by air pressure). <S> If I remember correctly, the AF 447 investigation concluded that the pitot tubes had thawed and began functioning properly well before impact; it was not the loss of airspeed indication that prevented the pilots from salvaging the situation. <S> By this time the pilots were confused and thought <S> the airspeed indication was still malfunctioning because it showed a much slower speed than they thought they ought to have -- whereas in fact it was working perfectly well. <A> The short answer to this question is that commercial airliners do have GPS and they have for a long time. <S> AF447 almost certainly would have been equipped with GPS. <S> While what Terry said about the difference between airspeed and ground speed is very true, AF447 could have seen from their GPS unit that they were moving much slower than what they should have been. <S> Unfortunately, judging from the cockpit voice recorder transcripts, it seems that they were panicking and failing to think logically or communicate well with each other. <S> It was almost entirely a case of pilot error, not lack of accurate information. <S> The pilot in the right seat was almost continually pulling back on his side stick. <S> This caused the aircraft to climb and bleed off airspeed until the wings stalled. <S> Even after the aircraft entered a stall condition, the pilots never lowered the nose, which would have recovered from the stall. <S> Instead, the pilot in the right seat actively held the nose high for the entire descent to the ocean. <S> Also, the pitot tubes thawed several minutes before the actual crash. <S> All of the instrument indications were correct for quite a long time before the aircraft hit the ocean. <S> For more information on AF447, see Popular Mechanics' annotated cockpit voice recorder transcript of the incident. <A> Airliners do have GPS units. <S> As the other answers and comments have indicated, GPS does not provide airspeed (or angle of attack) information. <S> It would seem reasonable to use the GPS as a backup in the following way: Under normal operation, the difference between TAS and the GPS estimate (allowing for some computational latency) should be fairly constant (the difference being the wind speed). <S> When the difference exceeds some noise threshold for a period of time it issues a warning. <S> This wouldn't help in the case of Aeropero 603 but may have helped in the Air France 447 incident. <S> (To clarify what I mean by help, I mean to reduce cockpit confusion.) <S> In the former case, a similar tracking system between the radar altimeter and thebarometric altimeter may have helped.
|
Airliners do generally have GPS receivers, but GPS doesn't give you the information that's needed in this case.
|
Why do passenger aircraft have the little airjets over each seat? I never turn them on, but I do turn them off if I notice them. Is this a relic from the age when people lit up next to you and you wanted to blow away the smoke? The system must weigh almost a ton on a large aircraft and seems pretty unpopular and hard to maintain. <Q> Why do airliners have them? <S> Because passengers like them. <S> When you're sitting in the penalty box waiting for a departure slot and the air conditioning system is barely running the extra cool air you can get from those vents may be the only thing keeping passengers from strangling the screaming child kicking the seat. <S> Opening these overhead "gasper vents" and directing them at the passenger's face provides a quick way of doing this. <A> The airjet openings are connected to a long duct running along the ceiling. <S> Since the air volume inside the cabin is restricted, fresh air must be pumped into it constantly. <S> It is bleed air from the compressor section of the engine, which is first cooled and then enters the cabin via those ducts which feed all the little vents or airjets, as you call them. <S> Passengers can open or close them individually and direct the flow for best comfort. <S> The general idea is that some vents will be closed, but enough are open during every flight so the needed recirculation of air can happen. <S> If more are closed, the pressure in the duct will be higher, so the flow through the remaining vents will increase. <S> The total weight of all the cabin ducting is a minor consideration, it's only a few dozen gram per passenger. <A> The primary reason is that not everyone likes the same temperatures. <S> I happen to be cold-natured and like to be warm. <S> Other people are hot-natured and like to use copious amounts of air conditioning. <S> These allow all of us to stay relatively comfortable in the same cabin. <S> Also, when you're sitting on the ramp in the summer, it's more than 100 degrees Farenheit outside, and the boarding door is still open, you'll learn to appreciate these things quickly, especially if you've been standing in the jetway a while before taking your seat. <S> Personally, I usually turn mine off during flight, but I do tend to use them on the ramp and sometimes during taxi in the summer and/or unusually hot climates. <A> Lowest cost is king if you can get away with it. <S> Personal air vents provide more flexibility than if they were absent and the overall cost is lower. <S> If personal airjets are available then the jet temperature and maximum available flow can be set to suit people with preferences on the cold side of normal, while the mean temperature can be hotter than would suit a significant proportion of people. <S> If, instead, the cabin needed to be maintained at a temperature that most people would consider acceptable then, in the absence of personal vents, the whole cabin would need to be cooled to that temperature. <S> Some people would then feel too cold, which can be dealt with by clothing or blankets, and most people would be comfortable. <S> In the first case you have lower than otherwise energy use with "outliers" being addressed with airjets. <S> In the second case you have higher than otherwise energy use with outliers being addressed with blankets. <S> The energy cost of the blankets is zero <S> but overall it still costs more this way. <S> FWIW <S> I'm an air-jet loving traveller and greatly dislike aircraft without them. <A> Although probably not the primary reason airlines have them in the first place, there is another great reason to use them. <S> Having fresh "outside" air blow in front of you displaces the viruses/bacteria/etc. <S> from sick passenger's coughs and sneezes away from entering your nose and mouth. <A> The practical use is to fight rising temperatures and odors, but i also quite like the oxygen.
|
Also a common "cure" for airsickness is fresh air -- blowing cool air over someone's face will often help with symptoms of motion sickness, and may prevent a nauseous passenger from actually vomiting. Make the passenger feel he's in control of something.
|
Are there international standards to Air Traffic Control procedures similar to US standands? In regards to air traffic control, FAA Order 7110.65 is the standard for policy and procedure in the USA. Do other countries use this also? Is there an 'international standard' for air traffic control? If so, are there any notable differences between that and the service provided by U.S. FAA? <Q> ICAO Annex 11 "Air Traffic Services" is probably the top document. <S> Implementations in national law might vary. <A> From what I've been told, back when ICAO started up, they basically copied for their manuals, what the FAA had and used at the time. <S> Over the years, the two have diverged in their designs. <S> There is no official/major standard, but most countries hold towards the ICAO recommendations, at least in general form. <S> ATC's main purpose is the safe, orderly and expeditious movement of aircraft. <A> The FAA and EUROCONTROL jointly published a document in 2013 that provides a comparison of air traffic management starting in section 2. <S> Most differences have to do with the fact that the EU is comprised of multiple countries, while in the US, the FAA has full authority. <S> Organization: <S> The US system is operated by one single service provider using the same tools and equipment, communication processes and a common set of rules and procedures ... <S> [while] the European system is much more fragmented and ANSPs are still largely organised by State boundaries. <S> Route/airspace management (including special use airspace): <S> [T]he Federal Aviation Administration (FAA) is responsible for airspace management and route design[;] in the amalgamated European ATM system, airspace design remains the prerogative of the individual States. <S> Direct link
|
Every country in the world generally operates from their own manuals. The International Civil Aviation Organization, ICAO, also has a standard that it recommends, and many countries have copied.
|
Should I log flying lessons from the start? I've recently started taking flying lessons and was wondering if I should begin logging my flying hours immediately? I'm aware there are minimum hours for each license certification, so I'm assuming I should be noting down my flight time right from the start but my instructor hasn't really said anything about it yet. <Q> Now for the first few lessons, it'd be ok to not have your own logbook yet, but you should get one. <S> Hopefully your instructor has kept his up to date, and can build your logbook in terms of flight times since you started. <A> As has been mentioned you should log hours as soon as you start flying. <S> All training hours with a CFI count towards your license, if you are paying for those lessons, you should log them. <S> As for books, also as mentioned there are a few kinds out there <S> but if you are starting with your PPL a basic log book will suffice. <S> There are also many paid, online services that come in the form of tablet/smartphone apps that are now FAA accepted as official logs (and your instructor an even sign them digitally). <S> This is a nice solution as you don't have to worry about your data getting lost. <S> I will personally be moving to this soon (when I start my instrument training). <S> Side note: if you have an iPad or iPhone there are lots of cool flight apps out there that are now legal replacements for paper maps, although you should still carry a paper or second digital back up. <A> Yes you should whether you are PIC or not, solo or dual. <A> Assuming you are flying in an FAA "controlled" area, you " must document and record the following time [...] : (1) Training and aeronautical experience used to meet the requirements for a certificate, rating, or flight review of this part. " <S> (FAR §61.51(a)). <S> Now this is for you, but your instructor should have a look at FAR §61.189(a), where it says: " A flight instructor must sign the logbook of each person to whom that instructor has given flight training or ground training ". <S> So, you don't have to log the time, if you don't want it to count to your training, but your instructor is required to sign your logbook if he gives you any flight training. <S> For every day life I would say this should be interpreted as:
|
Yes you have to log your flight time when you train for a license! Yes, you should be logging from the start.
|
Can you fly an airplane at a 90° roll angle without losing altitude? I've seen this answer to the question about flying upside-down, but tilted by 90°, there should be no surface creating lift (except maybe the vertical stabilizer). <Q> It depends. <S> As always. <S> If thrust is high enough, why not? <S> Knife edge flight <S> is a regular part of aerobatic performances, and the fuselage is producing almost <S> * all the needed lift. <S> This requires Enough speed, A low ratio of aircraft mass to fuselage side area, and Enough rudder deflection to trim the aircraft in a sufficiently high sidelip angle. <S> For horizontal flight your installed thrust must be sufficient to compensate for the high drag in this attitude. <S> This should be no problem with powerful propeller aircraft if their fuel system keeps them supplied at this attitude. <S> Jets must make sure that the sideslip angle can be tolerated by the intake. <S> The smoke from the exhaust indicates that this biplane flies horizontally. <S> Yes, it is a large model airplane (not man-carrying, but almost big enough for that). <S> But the laws of physics don't change with scale. <S> For an example of a full-size aircraft doing a knife edge, see this video . <S> Thanks go to @romkyns for pointing this out to me! <S> Note the rudder deflection to keep it at this angle of sideslip. <S> Direction is controlled with the elevator. <S> At this rate of sideslip the propeller thrust contributes to overall lift as well, however, the vertical adds a substantial downforce in order to trim the aircraft and the fuselage has to supply the remaining lift. <S> * Almost means that the propeller will carry some of the weight, but the large downforce on the vertical needs to be compensated, too. <S> In sum, the lift contributed by the fuselage is very close to the weight of the plane. <A> Regular airplanes, no. <S> They depend on lift produced by the wings and fuselage to stay airborne. <S> No aircraft that I know of can produce enough lift with its component tilted 90°. <S> This all assumes 'normal' airplanes though. <S> If you have enough thrust, there's nothing that says you need to depend on wings for lift, and if your thrust is vectored at least a little downwards producing enough of a vertical component to keep you from descending, it won't matter which direction anything else is pointing. <S> The extreme example of this is of course space rockets. <A> This happens (for several seconds at a time) as part of the "hesitation roll" aerobatic maneuver. <S> It depends on the fuselage alone for lift (in excess of the vertical component of thrust), so the nose has to point into the sky and the rudder is used to maintain that attitude. <S> Because fuselages have rather dismal L/D <S> it will require sufficient thrust, or bleed off a lot of speed. <A> During "normal" flight with wings level, the amount of lift generated will vary with the wings angle of attack (alpha). <S> Within the normal flying envelope of the aircraft, the relationship between lift and alpha will be nearly linear. <S> In an ideal situation, with symmetric airfoil and not considering fuselage/slipstream effects, at zero degrees alpha, no lift will be generated. <S> There sideslip angle of the aircraft is normally called beta. <S> In normal straight and level flight this is near zero, as no sideways lift is desired. <S> If you roll the aircraft 90 degrees and maintain it, you can with an alpha near zero and a sufficiently high beta angle generate sufficient sideways (now directed skywards) <S> lift to maintain level flight, if the shape and size of the fuselage allow this. <S> (This is the knife edge maneuver illustrated by the picture in Peter Kämpfs reply). <S> Aerobatic aircraft can be designed for this. <S> Some aircraft might be able to maintain altitude momentarily in knife edge, but will be unable to maintain the relatively high airspeed required to do this, and will eventually start descending. <A> We do that all the time with our radio-controlled airplanes. <S> It's called a knife-edge maneuver. <S> Maintaining altitude is easy provided you have enough power and rudder surface area, but maintaining a straight line (with elevator) is usually very tough. <S> Not every radio-controlled aircraft can do it though. <S> Usually the planes with small rudder deflection cannot hold altitude if their surface area is small. <S> Aerobatic ones can do it all day along. <S> In fact, an elegant way of coming out of this maneuver is to climb up at the end in that same orientation. <S> During this maneuver the nose of the airplane will always be a little higher (hence in a pitch up attitude) than the tail. <S> I don't see anyone doing it without pitch up and still maintaining the altitude. <A> Not really all that complicated. <S> It all depends on if the specific airframe is designed for such maneuvers and the power plant is robust enough for sustained operation in this mode of flight. <S> The Navy's Blue Angels and the USAF's Thunderbirds do this on a daily basis at their airshows. <S> Moving an airfoil to 90 degrees, 180 degrees, 270 degrees, or even through 360 degrees (barrel roll) is accomplished through the wings ailerons. <S> Most aircraft capable of aerobatic maneuvers have trim tabs on ailerons, rudder and elevator to assist in prolonging such maneuvers. <S> Although most light aircraft do not have trim tabs on the rudder and elevator. <S> I have witnessed a Pilatus Porter (Fairchild) take off near vertical with less than a 40 foot ground roll. <S> Granted it was stripped down and supercharged but it performed as advertised. <S> I think there was a Youtube type video on this out there somewhere at one point. <S> The demonstration was performed by the US Army in the 1970s.
|
MANY aircraft can sustain flight in horizontal flight with the wings 90 degrees to the ground.
|
Why does the Mitsubishi MU–2B have its own SFAR? The Mitsubishi MU-2B has a very long & detailed SFAR 108 that details the trained and currency requirements for anyone who wishes to manipulate the controls of the plane. I'm wondering what incidents or accidents and unusual handling characteristics required a Special SFR for this plane. <Q> Since the MU-2 weighs less than 12,500 lb, a type rating is not required to fly the plane, so pilots only need a multi-engine rating. <S> However, it is a high performance pressurized aircraft that requires more skill to fly. <S> Mitsubishi Heavy Industries asked the FAA to create a type rating requirement for the MU-2 , but the FAA decided on creating the SFAR instead, which is more strict than a type rating, especially in the amount of training specifically required. <S> Research showed that the accident rate of the MU-2 from 2001 to 2005 was not really exceptionally high compared to aircraft of similar size and performance. <S> While the accident rate was higher than some, it was also lower than others. <S> However, the FAA received a lot of pressure to create a rule for the MU-2. <S> Regardless, the accident rate has gone down significantly since the FAA created new regulations for the plane. <A> According to Wikipedia (or at least my reading of the article) <S> http://en.wikipedia.org/wiki/Mitsubishi_MU-2 <S> It looks like there were a lot of incidents in the plane, <S> enough that the FAA seems to have investigated the plane specifically and now advises/requires some special training for it. <S> As any government agency would they also issued lots of paperwork as a result thus your findings. <A> The MU-2 has had a very bad safety record. <S> From various sources I've talked with over the years, if you lose an engine, you need an excessive amount of altitude to recover. <S> All these things coupled basically put the FAA to put in a Special rules for anyone wanting to fly the MU2.
|
Same with the other SFARs, there's usually been a rash of incidents outside of what's normally taught for the category/class, that requires special or additional training. Various design issues I've heard are related to it, from possibly overpowered engines, to short wings.
|
How much jurisdiction does the FAA have over military aircraft? The FAA controls just about everything about civilian aircraft in US airspace in terms of regulation, certification, flight rules, etc. Do they have any authority over military aircraft beyond requiring military flights to communicate with ATC for safety and designating certain areas as military airspace? This question addresses retired military aircraft in civilian use, and one of the answers to this question mentions a "Surplus military" category, but nothing about active military. I'm asking about current, active military aircraft in terms of certification, pilot licensing/qualification, etc. <Q> If they are being operated by the military, not much. <S> Military pilots have a military pilot's license (which can be converted to an FAA license with a little paperwork), and the airworthiness and maintenance standards for active military aircraft are defined and managed by the branch of the service responsible for the aircraft. <S> (This is similar to, but legislatively distinct from, Public Aircraft Operations .) <S> This doesn't mean the FAA is completely silent about military operations/aircraft: There is guidance for military aircraft that are based on commercial designs (also available in an easier-to-read Advisory Circular: <S> AC 20-169 ), which would be applicable to aircraft like the VC-25 ("Air Force One"). <A> All good answers, just to add: <S> Yes, our regulations are usually more stringent such as weather minimums for example (filing, including an alternate, fuel requirements, night, etc.). <S> However, with other things we do have a bit more leeway than civilians. <S> I'm not going to list all the differences, but if you want you could check out some of the publications we're bound by: AFI 11-202 Vol 3AFMAN 11-217 <S> Vol 1AFMAN 11-217 <S> Vol 2AFMAN 11-217 <S> Vol 3 <S> That's just a subset of what binds us; I'm not going to list them all here <S> but we have regulations and procedures for specific jets based on MAJCOMs, Ops Groups, Wings, etc. <S> The military changes a lot more quickly and often than civilian flying does. <S> Additionally flying in one MAJCOM may be totally different than another. <S> Likewise, one airfield, wing, or squadron will have totally different SOPs than another airfield, wing, or squadron. <S> Finally, although VFR aircraft CAN fly through a MOA, please don't do it. <S> It interrupts our ops since we have to call knock-it-off and either wait for you to leave or proceed to a different area. <A> As mentioned here and here , FAA's responsibilities include: Developing and operating a system of air traffic control and navigation for both civil and military aircraft <S> However, FAA does not govern military aircraft. <S> The military has their own rules and regulations, but the military follows FAA regulations when flying in National Airspace . <S> There is airspace in the US and elsewhere that is set aside for military operations such as the Barry Goldwater Gunnery Range . <S> Military jets can fire at targets on the ground and civilian aircraft are kept out. <S> There are many others. <S> As needed, FAA does make special allowances for the military. <S> Below is an example of a Military operations area .
|
Military operations can exempt themselves from the FARs (as a matter of practice they don't : When operating in the US National Airspace System they follow the same operational regulations we do, but as a matter of regulation they're subject to the military's rules for airworthiness, maintenance, etc.).
|
UAV project in aerospace department I am 2nd year PhD student in Physics. Can you think of any UAV project which won't contribute to army? UAV designing is a career of my dream, but I want to serve the greater good. However, all advances are developing in military field. <Q> But guess what: Development took much longer than initially expected, and funding gaps could only be filled with DARPA money. <S> In the end, military contracts keep many high-tech companies alive which could not support themselves exclusively with civilian money. <S> If your field of interest has military applications, it will be very hard to stay true to your ethical standards. <S> I would dispute your claim, however, that all advances take only place in the military field. <S> Apart from GPS, many advances which make UAVs practical are connected to civilian-driven technological progress. <S> Only when it comes to issues like reserving airspace for UAV operations, the military is in a much easier position than civilian operators which must wait for slow-moving government bureaucracies to adapt to progress. <S> The discussions we had with the FAA in 1990 on how to operate UAVs were surreal. <A> Here are a few non-military ways in which drones have been used: the city of Ottawa has been using drones to scare away <S> geese in order to limit local goose population; wildlife surveys, in particular for endangered species. <S> This has been done for orang-outans , whales, cranes and others; fighting illegal hunting; assisting firefighters ; dusting crops ; replacing helicopter pilots in taking aerial footage for movies; cartography (though this is a civil and military application); search and rescue missions; traffic monitoring to determine congested roads or find the quickest route for emergency vehicles; enforcing environmental laws (e.g. determining where dumping of toxic waste is done and by whom) ... <A> Amazon wants to deliver packages with UAVs. <S> So does Google . <S> Even military contractors like Boeing and Northrup Grumman see applications in agriculture. <S> Of course, there's also a growing field in selling them for retail . <S> While other countries have better regulatory processes right now, the FAA is preventing much progress in the US. <S> If you come up with your own idea, then why not start your own business? <S> There are lots of possibilities.
|
One would be the Aurora Flight Sciences Perseus , which started as an unmanned instrument carrier for flights into the south polar vortex, in order to study ozone depletion.
|
Why would a commercal flight circle while enroute? While selecting random flights to learn about FlightRadar24 , I came across AC7311 flying from Toronto, ON (CYYZ) to Indianapolis, IN (KIND) , and saw that it flew a couple of circles southwest of Lima, OH (near KAOH ). What are some of the reasons Air Traffic Control would direct the pilots to do that? <Q> As others have noted, this is called a holding pattern, which is used to delay an aircraft while in the air. <S> Of course, this takes time and fuel, so the system works to prevent this from being necessary. <S> The primary use of holding patterns is by ATC to delay arrivals . <S> This could for traffic reasons, to delay the aircraft until it can join the line of arriving aircraft. <S> It could also be for facility reasons. <S> An airport can also be closed for weather, or for another reason, in which case all aircraft must enter a hold, or land at an alternate airport. <S> Pilots sometimes need to use holding patterns as well. <S> If they have an issue with the plane, they may need time to follow their checklists and diagnose the problem. <S> ATC will give them a place to hold for this time. <S> Standard arrival procedures generally have holding points published for these cases. <S> When a holding pattern isn't defined, one can be created. <S> The aircraft will fly for a standard time before turning around, and repeating as necessary. <S> A better FlightRadar example is perhaps the following image, showing three aircraft in the stack and one leaving it Source <A> ATC can direct a plane to enter the pattern in order to ensure separation between landings:two planes might reach the airport almost at the same time, the first might be directed to land, the second will have to wait. <A> This maneuver of doing a 360° turn is issued by ATC. <S> There are two reasons for this: to increase spacing between your flight and another airplane <S> it was one or more circles in a holding pattern <S> By looking at the map, it appears that what your interested flight did was a holding pattern, because it is not too far to the airport.
|
Bad weather can reduce the rate at which an airport can accept aircraft, meaning some will have to enter a hold. It's called Holding Pattern .
|
What is the maximum altitude a skydiving plane can fly? Is there a standard maximum altitude which skydiving planes can fly? I am mainly asking about the sports activity, not military parachuting. <Q> Qualifier: I am a master parachute rigger and taught sport skydiving for 10 years. <S> Standard jump altitude is 12,000 feet AGL - this is one turn of the standard parachutist's altimeter. <S> This height provides 1 minute of freefall, is within reach of a Cessna with a decent engine and does not require supplementary oxygen. <S> For most places, this means an operating altitude between 12,000 and 15,000 feet MSL. <S> Dropzones in high areas like Denver will reduce their jump altitude to 9,500 feet AGL mainly because the piston-powered planes take too long to climb higher and/or the upper part of the climb runs into the oxygen zone. <A> Dropzones significantly above sea level typically either reduce their jump height to stay under 15,000 MSL or provide supplemental oxygen in the plane and go up to 18,000 MSL. <S> Many dropzones will offer jumps from 18,000 MSL for an additional fee over the regular jump. <S> Supplemental oxygen is provided. <S> Jumps in the 18,000-23,000 MSL range are also possible but rarer because of the increased needed for coordination with ATC. <S> Above 18,000, the risk of hypoxia increases rapidly. <S> This video shows jumpers suffering from severe hypoxia at 21,000'. <S> There is at least one facility in the United States that takes recreational skydivers up to 30,000 MSL. <S> It requires additional training and wearing oxygen in freefall. <S> This facility uses a King Air, and I know it has also been done from a PAC750. <A> If there's such a thing as a standard maximum altitude for sport parachuting, the best answer would be 15,000' MSL, as above this CFR 91.211 requires supplemental oxygen for all passengers - and providing this to sport jumpers would be an expensive nuisance. <S> Note that this does not vary with ground elevation - <S> so indeed jumpers in the Denver area will not be able to get as high above the drop zone (and thus as much freefall time) as those starting from a lower altitude. <S> Note also that this is a limitation on people - there is no standard maximum for jump aircraft <S> Some aircraft types (e.g. Cessna 182) would struggle to get anywhere near 15,000' MSL in a reasonable time. <S> Others (e.g. Cessna Caravan) can haul a full load of jumpers to 15,000' MSL rapidly and without breaking a sweat. <S> The Caravan could carry jumpers to its service ceiling of 25,000' <S> provided they had oxygen and the pilot obtained ATC clearance (required above FL 180 = 18,000'). <A> Paul said "Standard jump altitude is 12,000 feet AGL -This <S> height provides 1 minute of freefall, " that is incorrect actually... <S> Basic skydive has an exit altitude of 10,000 feet. <S> This is the average altitude for skydiving here in the US and common to most Cessna aircraft dropzones. <S> This means you will skydive from 10,000 feet above ground level. <S> At this height, your skydive will last 30 seconds - <S> that's how long you'll be in freefall. <S> You'll then have a few minutes under parachute as you make your way to the ground. <S> EXTREME SKYDIVING ALTITUDE: <S> 14,000 FEETWhen <S> you jump from 14,000 above ground level, you'll be in freefall for around 60 seconds. <S> THE HIGHEST DAILY JUMP is: 18,000 FEET <S> At a skydiving altitude of 18,000 feet, skydiving lasts for 2 minutes <S> Any way the correct answer is basic skydive from 10,000 feet above ground level. <S> At this height, your skydive will last 30 seconds
|
As paul mentioned, "standard" altitudes for sport skydiving facilities near sea level are in the 10,500-13,500 AGL range.
|
In calm winds, which runway should I select at an untowered airport? In calm wind situations, approaching an uncontrolled airport with no other aircraft reporting on CTAF, which runway should I select that would cause the least safety hazard? Especially at an airport with one runway, I don't want to set up to land head-on with an aircraft flying without a radio. <Q> Often uncontrolled fields will publish a preferred calm wind runway in the Airport/Facility Directory. <S> When one isn't published the calm wind runway is usually the longest runway, which gives you a 50/50 chance at guessing right. <S> To further reduce your likelihood of winding up face to face with another arriving aircraft you should self-announce on the CTAF and overfly the field to observe the traffic pattern. <S> Also, turn on all the external lights 5 miles out. <S> If there is traffic in the pattern you should work yourself into the same pattern everyone else is using. <A> You can talk about obstacles and runway lengths and not flying into the sun and all sorts of other minutiae that probably don't apply in calm conditions in a Cessna 172. <S> At some point you've decided that there's no one in the pattern, but you're going to keep looking for traffic throughout the pattern just like you learned from your CFI, and you have to pick a runway. <S> For me, I'll pick the one that requires the least amount of flying, just like the Hawker 800 pilot will do. <S> I realize that this technique is not for everyone, but if I'm heading southbound, and there's a nice N/S-ish runway, I'll make that straight in, just like it says in this AOPA article : <S> Straight-in approaches are always a topic for discussion. <S> Under VFR conditions they are acceptable only if there is no conflict with other traffic. <S> If I'm heading southbound, and there's an E/W-ish runway, I'll enter a long L or R base, regardless of which way traffic pattern is. <S> If I care about the traffic pattern for some reason (obstacle or noise abatement), I'll make an overhead entry, which means overfly the airport and enter left or right downwind. <S> If you're uncomfortable with a straight-in, base, or overhead entry, look for the runway where you can make a downwind or 45 entry with the least amount of maneuvering for L or R traffic as per the chart: <A> In addition to voretaq7's answer, you could also check the terminal aerodrome forecast (TAF) / maximum elevation figure (MEF) and see what is the weather forecast. <S> If it's IMC and the airport has only a single ILS <S> , then takeoff from the runway with the ILS (since that's the runway IFR aircraft will be landing on). <A> In regards to traffic avoidance, unless the airport has a preferred calm wind runway, there's not really a hard and fast rule for which runway you should choose. <S> However, as you're approaching the airport, you should be looking for traffic both in the pattern and on the field. <S> If there's traffic already in the pattern for a given runway, join that pattern. <S> And, of course, if there's traffic on a runway, don't set up for the same runway in the opposite direction. <S> Once you've selected a runway, continue to keep your eyes open. <S> You should have a view of the runway for most of the pattern, so you should be able to see if someone without a radio also happens to not look out his window and lines up for departure on the opposite runway. <S> While, as the arriving traffic, you should have the right-of-way over departing traffic, you'd obviously want to break off your approach if the runway is occupied.
|
If the pattern is empty my personal practice is to pick the approach to the longest runway with the fewest obstructions, and ideally one that doesn't overfly residential areas (where it's practical to avoid doing so).
|
How do I keep coordinated on a windy day? I've noticed on windy days that keeping the aircraft coordinated can be difficult -- the ball will tend to bounce back and forth in the turn coordinator, and I will find myself "chasing" it with the rudder pedals. Any advice for managing this situation? At cruise it doesn't worry me as much as setting up for approach to land. I think I've read too many stall/spin in the pattern stories lately... <Q> Don't chase the ball. <S> Heck if you're VFR/VMC, you should barely be glancing at the ball or any of your instruments and should have eyes outside. <S> Remember flying a little uncoordinated alone is not going to force a spin. <S> Stall + <S> Yaw = Spin <S> So how do we mitigate this during gusty approaches? <S> We fly a little bit faster. <S> I like to use 1/2 the gust factor and add that to my final approach speed. <S> I'm not saying accept being uncoordinated, but when it's gusty out you don't chase airspeed, <S> so why chase the ball? <A> The ball in the turn coordinator is loose, and it wants to stay in the same place as an object at rest wants to stay at rest. <S> When the ball seems to be bouncing around <S> it's actually the airplane bouncing around it due to rough air rather than the aircraft being our of balance relative to the airflow. <S> When you saw at the rudder in rough air you are actually throwing the aircraft out of balance one way <S> and then the other. <S> You can end up over-controlling with coarse rudder inputs and possibly snap-rolling the airplane, although that's unlikely. <S> More likely you will just tire yourself out and waste concentration. <S> Keep your feet nice and steady on the controls, there's rarely any need for large inputs. <S> When the air is smooth have a glance at the ball and make corrections then. <S> Keep your vision outside the cockpit as much as possible and keep your airspeed up. <A> In a steady wind, even in gusty conditions, the wind direction doesn't change much, except by a few degrees. <S> Where things get tricky is when the winds are variable <S> (METAR: 180V240 or VRB005KT) <S> , there's wind shear, or there's turbulence, in which case you will be working the stick as well as the rudder to keep the plane on course and coordinated. <S> You'd have to get the ball pretty far (at least one ball diameter) out of whack to be dangerous, but your back seat passengers will feel any lack of coordination.
|
Its enough to glance at the ball each time you enter a turn and each time you return to straight flight, and make a gentle correction.
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.