texts: If an airline purchases an aircraft, do they have to/feel compelled to change the livery?

texts:
If an airline purchases a used commercial aircraft, which would be painted in the livery of its previous owner, would the new airline ever be required (by law) to re-paint the aircraft in their own livery?

I am also curious what happens if a private individual were to purchase a used aircraft from an airline, again painted in their livery. Would they be allowed to fly it for some time still bearing the livery of the airline that used to own it?

If there is no law regarding this, then is there a general practice? I.e. most airlines would just keep the old livery until the airplane is due to be re-painted?


texts: Can an ADS-B In/Out equipped aircraft increase ground station coverage?

texts:
Suppose a ground station can detect aircraft in a 200 km radius with ADS-B In.
There is a plane A at 180 km, and another one B at 250 km, both equipped with ADS-B In/Out.

If ground station receives A, and A receives B: Can B information go to ground station using A as a repeater?


texts: Similar books to this: "konstruktion der luftstrahltriebwerke by Stammer and Jahrig" for Structural and machine element design of jet engine

texts:
I have been reading recently this book. It is unbelievable and has great content. I would like ask if any of you know any other, similar, more modern, of course focused on structural design with such great figures.
https://www.amazon.de/Konstruktion-der-Luftstrahltriebwerke/dp/B00J6XD28O


texts: What are the advantages and disadvantages of a delta wing compared to a swept wing?

texts:
What advantage does a delta wing have over a swept wing with high AR for supersonic flight? And what disadvantage does a delta wing have over a swept wing with high AR for transonic flight?

The Concorde is made to cruise at supersonic speed--delta wings.

Most commercial airliner--swept wing with high AR.

Would you design a supersonic airplane with the conventional airliner swept wings? On the other hand, would you design a transonic flight with delta wings?


texts:
As a followup to Why do turbofan blade tips exceed the speed of sounds while prop tips should not my question is: why have rings on propellers not been used to overcome this problem?

It seems from this site that they are produced at least for maritime use.

According to this site and this site it seems to have advantages and experiments have already been done as I can see from the picture. (I do not know how reliable it could be though)


texts:
I was listening to this ATC conversation (3:10) and wondering:

Why are tugs the least priority when talking to ground? I am thinking that some tugs might be towing aircraft that need to depart.
Why are tugs even talking to ground? Whenever I am on a plane at some airports, I see roads next to taxiways with cars, buses, and other vehicles that stop when airplanes are about to cross their paths (such as the roads with the dashed white lines in the picture). Do tugs travel on roadways or on taxiways? Do tugs communicate with ground while they are on a roadway?


texts: What are the consequences of flying GA without a license (certificate)?

texts:
As far as I can tell, in the U.S., 49 USC 46317(a) makes flying without a proper certificate a crime punishable by fine and/or imprisonment.  However, the FAA is a regulatory agency, which means it can only assess civil penalties (e.g., civil fines or revocation of certificates).

In practice I've heard (and would expect) the FAA gets quite exercised over "airmen" found to be carrying passengers for hire without current and proper certificates.

What I'm wondering is whether individuals have ever been, or are routinely, subject to any scrutiny or regulatory or prosecutorial action if they fly without certificates and don't commit any other egregious violations of FAA regulations?  E.g., if you only fly registered aircraft for your own amusement, and you never break a serious airspace rule, but you never get an FAA certificate, could you expect to go your whole life without any trouble from the FAA?  If not, what sort of trouble might you expect and how would you get into it?

And has anyone ever faced criminal prosecution for flying without proper certificates who did not also commit a gross violation of safety while operating an aircraft for hire, or some other felony (e.g., smuggling)?


texts: Could a Personal Locator Beacon or EPIRB carried by a passenger aid in locating a downed airliner?

texts:
There've been a lot of questions lately about tracking aircraft, and after a conversation with a friend of a friend I started wondering:

Could a PLB or EPIRB carried by a passenger or crew member aid in locating a downed or missing airliner? There are a dozen or so brands out there, most using similar technology, like this ACR ARTEX unit:

Now, I'm well aware of the FAA and FCC regulations about electronic devices in flight, and that's not what I'm interested in. I also realize that airliners already carry an ELT.

If a paranoid passenger brought one on board, would these devices function at all from inside an airliner cabin? Some feed GPS location data to a 406MHz locator beacon, and those would potentially be less useful (as they'd have to be at hand and probably triggered manually. Others, like the Spot GPS tracker, have the ability to upload GPS track data on the fly to satellite communications networks such as Iridium.

I'm personally skeptical, given that GPS generally needs a clear view of the sky and that a fuselage seems likely to block or reduce a 406Mhz ELT signal, but I'm curious to know if there's any information out there.


texts: How do the oxygen masks deploy after a cabin decompression?

texts: Is there any sensor incorporated on the Passenger Service Unit that tells the masks to deploy when a cabin decompression occurs?


texts: How realistic is the aviation crisis in the recent Spider-Man movie?

texts:
In the 2014 film The Amazing Spider-Man 2, there's a sequence in which a villain disables the city's power grid.  All over town, stuff loses power... including the local airport and its air traffic controllers.  This is a problem because there are currently two planes inbound, on courses that will cause them to collide with each other in midair unless the tower can warn them in time!

Luckily, Spider-Man finds a way to defeat the villain and the ATC gets their power back just in time to radio the planes to change course, and they miss each other by an extremely narrow margin.

Putting aside for the moment the question of whether or not a real ATC would have their own independent backup power source, how realistic are the two premises of this crisis?

1) That two airplanes would be inbound towards a major airport on courses that would cause them to both occupy the same position in 3D space at the same time, and

2) That neither pilot would actually notice this until either the tower told them or something suddenly goes CRUNCH!  Do commercial jet liners not have their own radar at the very least?  (Heck, my car has little radar emitters that warn me if something is too close!)


texts: What are differences between vortex, swirl, eddies and wake?

texts: These terms seem to have the same meanings. Can anyone differentiate them?


texts:
In terms of technical capability, what are the comparative advantages and disadvantages between the following?

CSC DUATS from Computer Sciences Corporation
DTC DUAT from Data Transformation Corporation
www.1800wxbrief.com from Lockheed-Martin


texts: Once you have passed the oral portion of a checkride, do you have to retake it ever again?

texts:
I recently attempted to take my Commercial/ME/Instrument checkride. I passed the oral exam portion, but shortly after the engine started running rough. After making it through about 3-4 maneuvers and tasks, the DPE and myself called safety of flight and brought the plane back in. He did a discontinuance on my app for a new rating, but did check me off on the tasks performed. He stated that the tasks performed have a two month shelf life.

My question is, does the oral exam have the same shelf life since I passed it?

The reason this is a concern is that I have a deployment with the Guard in about two weeks. If the plane doesn't get back up and running, I'm hosed. My shelf life on the checkride stuff expires on 5/31 and I won't be back home from my deployment until early to mid-June.


texts: Is flow turning different from the Magnus Effect? If so, how?

texts:
The production of lift is much more complex than a simple
  differential pressure between upper and lower airfoil surfaces. In
  fact, many lifting airfoils do not have an upper surface longer than
  the bottom, as in the case of symmetrical airfoils. These are seen in high-speed
  aircraft having symmetrical wings, or on symmetrical rotor
  blades for many helicopters whose upper and lower surfaces
  4-8
  are identical. In both examples, the only difference is the
  relationship of the airfoil with the oncoming airstream
  (angle). A paper airplane,
  which is simply a flat plate, has a bottom and top exactly the same
  shape and length. Yet, these airfoils do produce lift, and “flow
  turning” is partly (or fully) responsible for creating lift. As an airfoil moves through air, the airfoil is inclined against the airflow, producing a different flow caused by the airfoil’s relationship to the oncoming air (my emphasis).
  PHAK pp.97-98

In what way is the "flow turning" being explained above different from the Magnus Effect (Bernoulli's Principle)? Are there any fundamental difference between the two? Aren't they the same in that they both use a speed difference in airflow between the upper and lower surface of an airfoil to produce lift?


texts: Does a Tower controller need to see an aircraft on final to give landing clearance?

texts:
If there is an IFR aircraft on approach that has already received an approach clearance, and he reports being at the final approach fix but the controller does not have him in sight yet, can the controller give the aircraft clearance to land at this point, or does he have to wait until he has the aircraft in sight (which may be on short final)?

And what are the rules for (let's say) a VFR flight on final (maybe the controller can't see him due to rain over the field, etc.)?  Also, are there any reference documents (ICAO/FAA/Eurocontrol) that have information on this?

Here's a more specific IFR scenario: let's say the aircraft is making a CAT I ILS or maybe a VOR DME approach, in a non-radar environment. Does the tower need to see the aircraft before giving a landing clearance? The runway itself is clear from other vehicles or aircraft. Does the controller issue a "continue approach" instruction until he can see the aircraft and then clear it to land? O does he just issue the landing clearance at the final fix ( if the runway itself is clear)?


texts: Were early military planes not pressurized?

texts: I just heard that  1930s-40s planes such as the B-17 were not pressurized. Is this true? If yes, then how did the military men survive at heights of 30k ft?


texts: Why aren't we using drone blimp/hybird airship for delivery?

texts: Currently, the heaviest weight a commercial drone (the type that delivers Amazon package, not the type that delivers tons of stuff) can lift is 4.5kg with a 30-45 minute battery life. A drone blimp/hybird airship might be bigger and slower, but it would take less energy--the lift is generated by the balloon or some lifting surface instead of the propellers. Since the Boeing 747 win against the Concorde because it can carry more people with a cheaper price despite much slower than Concorde, why aren't we using a drone blimp/hybird airship to deliver Amazon packages instead?


texts: Can a landing aircraft snag multiple wires when landing on an aircraft carrier?

texts:
There are 4 arresting wires on an aircraft carrier separated by about 50 feet and usually the pilot tries to snag the 3rd one but he does have the option to snag the first or second one.

What stops the tailhook from engaging the wires in front of the airfraft as well?   Is it assumed that they will also get engaged and the regulator on each arresting engine is tuned to accept it?


texts: Why is the combustion temperature in a turbojet engine kept low?

texts: Why the temperature of hot gas entering the turbine is maintained  far below the adiabatic combustion temperature?


texts: Why is the combustor volume of a jet engine decided by altitude?

texts: I have read that the combustor volume of a jet engine is decided by the maximum altitude up to which that aircraft will fly. I'm getting confused by that, because the maximum mass flow rate will occur at sea level so the combustor volume should be decided based on sea level. Can anyone explain how the volume is decided?


texts: How dissimilar are redundant flight control computers?

texts:
Facts

On Airbus aircraft there are computers to secure the flight envelope, or to move the control surfaces. FADECs totally control the engines. Computers take decisions in place of the pilots, or even against their commands. Boeing aircraft have similar computers, even if the crew has more authority.

A330 electronic bay, source, photo by 'swiss_a320'

Safety implications

Being critical, systems are redundant and supervise each other to detect possible failures and isolate failed components. However a computer can still be developed from faulty specifications, or be wrongly manufactured, and a program can contains bugs. If the same defect is present on all computers on the production line, the purpose of redundancy may be defeated, as they wouldn't be able to detect erroneous behavior.

This is better stated in this article:

  Because of the severe consequences resulting from a single point of
  failure, hardware redundancy is critical in DAL A systems. But if the
  aircraft uses a redundant architecture built with similar channels,
  that system will still be susceptible to common mode failures that can
  cause all channels to fail in the same way.

Question

What are the principles used in aviation to reduce the possibility for redundant computers to fail or to make the same errors at the same time?


texts: Is it possible to embed CL, CD, dCLda, etc, into a tensor?

texts: Is it possible to form a tensor (i.e. matrix) such that this tensor applied to the apparent wind vector produces a vector representing the resulting aerodynamic force?


texts: How quickly can a hot air balloon climb?

texts: What's a typical rate of climb for a hot air balloon, assuming stable air with no updrafts? I'm thinking of the classic 'sightseeing ride' type of balloon here.


texts: How to determine the traffic avoidance manuver?

texts:
Scenario A: I started the takeoff roll and then noticed another aircraft is crossing the runway in front of me, how could I determine what is the best avoidance maneuver, like full braking to abort the takeoff? Or proceed take off and leave the ground before the collision? Or change the aircraft heading just like a car driver to avoid the traffic, in which my aircraft could probably rushed out of the runway?

Scenario B: I am holding on the runway and ready for takeoff and another aircraft is on the final to land, should I initiated takeoff ASAP or exited the runway? If I initiated the takeoff and the landing aircraft also take avoidance action and do a go around, will things getting worse since we may collide in air?


texts: Can I log the flight as the authorized instructor on board? Commercial long cross country

texts: I was an authorized instructor on board for my students long commercial cross country. Do I log any of that flight time?


texts: How safe are airplane tours of the Grand Canyon?

texts:
I'm curious as a complete layperson who's looking at scenic flights with Scenic or Papillon. I'm not afraid of flying on commercial airplanes, but this is a private, single-engine flight around the Grand Canyon. I think the company has had a bit of a history of crashes with its helicopter program over the past 15 years as well.

The tour is two 45 minute flights, I haven't booked it yet. Should I be worried?


texts: What happened to Widereøe flight WF0597?

texts:
WF0597 was a scheduled flight from Bergen Airport Flesland (ENBR) to Kristiansand Kjevik (ENCN). The Embraer E190-E2 immediately started circling Flesland and continued for about 1 hour and 40 minutes, before making a stop at Flesland.

What could have happened to this flight such that it would behave as it did?

The aircraft never changed its squawk, indicating that it did not file an emergency.
Multiple aircraft landed while WF0597 was circling, including an E190-E2 also operated by Widerøe, indicating that nothing was wrong with systems/runway at Flesland.

A pilot friend suggested landing rounds, but this means that the flight was cancelled at some point, even though the websites of Widerøe and Flesland says it had departed as scheduled.

Is this normal? If not, any theories as to what might have happened?


texts: What is the difference between MCP and METO?

texts:
I was reading the Cessna 150H POH earlier today and noticed that the manual mentions something like "Normal cruising is done at 65% to 75% of METO power."

The Cessna 172S POH charts refer to cruising power as "75% MCP."

Given that METO stands for "Maximum Except for Take Off" and MCP stands for "Maximum Cruising Power", are the two terms the same thing or do they have differences?


texts: How to get data from Aeronautical Fixed Telecommunication Network?

texts:
I would like to download some NOTAMs and I know they can be obtained from the AFTN (Aeronautical Fixed Telecommunication Network)
.

Do you know a way to access such network and request obtain the data from it?


texts: How long before departure can an IFR clearance be copied?

texts:
When flying IFR under the FAA the departure procedure starts with copying an IFR clearance from ATC.

My question is, how long before departure is it okay to go ahead and copy down the clearance?

Sometimes clearances include void times. The context of my question is for clearances delivered, for example, be clearance delivery at a towered airport. These clearances don't include void times. What't the time limit on these clearances?


texts: Why wasn't Solar Impulse 2 cleared for takeoff?

texts:
I've recently been watching videos of the Solar Impulse 2 (HB-SIB) flights, and I noticed that on several occasions, instead of giving clearance for takeoff, the tower told the pilot that "departure is at your own risk".

In particular, this happened at Kalaeloa (PHJR) in Hawaii, at Dayton (KDAY) and at Lehigh Valley (KABE).

But, at Moffett Field (KNUQ), Tulsa (KTUL), and out of KJFK, the flight was "cleared for takeoff".

I couldn't spot anything obvious in the tower conversations to suggest why departure was at the pilot's own risk. Out of KDAY, the tower said that the runway the plane was using was closed (of course it's closed, there's an experimental solar airplane and ground crew on it), and at KABE the tower mentioned a jet that landed on the other runway a few minutes prior.

What happened here? Why was departure at the pilot's own risk?


texts: Using the APU for heating on the ground with engines shut down

texts:
I would like to refer one technical question to you that I couldn’t able to explain myself. It is from the FCOM Supplementary Procedures Chapter of a Boeing 737 Classic. This question concerns the use of APU as a heat air source on the ground with engines shut down. The supplementary procedure explains that under extremely cold weather conditions both packs may be used for more rapid heating.

It directs to open the Isolation Valve Switch which is reasonable. However it also says that during right pack operation only, under cold conditions, if the left PACK TRIP OFF light illuminates, position the recirculation fan OFF until the cabin temperature stabilizes.

Here, I don’t understand do they mean that left pack is INOP? I am confused because this procedure explains that both packs may be used!? And the other thing, why should I position the left recirculation fan to of if the LEFT TRIP OFF light illuminates under these conditions. As far as I know the recirculation fan reduces the air conditioning pack load, or am I missing something.


texts:
From take-off performance calculations I remember that the take-off and initial climb was expressed in a number of segments. Each segment had its own performance requirements. I presume they are described in some FAR / JAR but I don't know whether to look under certification or operational requirements.

What are the segments and how are they demarcated?

Do they differ for aircraft types (propeller vs. turbofan, number of engines?)

Are these segments used for certification, operationally or both?


texts: Can Flight Simulators (FSX P3D) give you the expecience you need to fly a RW plane?

texts:
So I am flying on the sim for about 7 years now, which 3 years on the (PMDG) 777 and 737NG. Flying on the sims is almost like the real world right now, you can download multiple addons (PMDG, Aerosoft for planes ORBX for scenery, REX and ACSC for weather, etc, etc), download checklists, join online networks (IVAO, VATSIM) and so on. But can step into a 737NG right now and fly it with my sim experience?

What are the real differences between the sim and real world if it's about flying. And if I would step into a 737 now, what challenges can I expect during flight, which I probably didn't encounter during my flights in the simulator.

Consider this:

I fly 7 years on the sim
3 years on the PMDG 737 and PMDG 777
Flown with multiple failures (Engine Fire, ADIRU failing, etc, etc)

Thanks in advance!


texts: How many types of tape do airplane mechanics use?

texts:
I was reading this blog linked from this answer, and it mentions

  “We never use, and don’t even stock, duct tape,” explains a veteran
  airline mechanic. “Some of the tapes we use cost hundreds, even
  thousands, of dollars per roll.

Which brings up the question, how many types of tape are used by airplane mechanics and what are they all used for? Obviously speed tape is one type and duct tape is not, but what else is there?


texts: What are the disadvantages of fitting underwing flaps to a Mirage III/5 fighter jets to lower landing speeds?

texts:
The Mirage III / 5 series of fighter aircraft are versatile aircraft, but has a high approach speed of 180 knots and a high landing speed, requiring long runways.

Underwing flaps, like those of the Gloster Javelin, would surely work, and the fact that they are close to the CG would not cause an acceptable pitching moment. The tailless swept wing Messerschmitt P.1111 also had flaps on its trailing edge.

Gloster Javelin in landing configuration

Tested on a small free flight glider, I found that the flaps on a delta resulted in a noticeable increase in lift and decrease in turning radius, the elevons were not overwhelmed by the downward moment of the flaps. Using trailing edge flaps on a the same delta wing model resulted in an unacceptable downward pitch that could not be counteracted by the remaining set of elevons.

I would think the system would work, however my question is what sort of performance effects: increase in weight, for example, and possibly drag, would result.

Later models of Mirage incorporated canards and other devices to reduce landing speed did Dassault Aviation overlooked this option or did they evaluate it and decide that it would not be worth it?

I would have incorporated these in any delta wing fighter I designed, at least to offer it as an option to customers like the tailor made canards were to be offered.


texts: Are there typical values of pitot-static and TAT probe measurement uncertainties?

texts:
I'm working on flight sensors for a project and I'm supposed to model noise in the Static Port, Pitot tube, and TAT probe measurements. I looked a lot for it online and could not get a convincing answer.

I need the uncertainties of Static port, Pitot tubes and TAT measurements. By uncertainty, I mean + or - certain pascals for Static port and Pitot tubes and + or - certain degree Kelvin for the TAT probe. Is there a typical uncertainty value for these, say for example a Boeing 747 and I guess a digital sensor as the worse case? I don't know much about the companies supplying these sensors or the installation method on the aircraft.

It would be great if someone could help me! Cheers!


texts: How can I calculate the drag coefficient for a given wing design?

texts:
I am building an RC plane (for the first time. I am doing it for a competition) with a twin boom configuration like this:

My wing shape is like this:

I decided that the lift should be 0.8g and I need to use this equation to find the wing area (as per the instructions)

$$F_l=\frac{1}{2}\rho v^2 S C_d$$

$F_l=0.8$

$\rho=1.225$

$v=12m/s$

Can you help me in figuring out the value of $C_d$ considering that I am using Clark Y aerofoil design?

After that, I will measure $b$ using the aspect ratio.

$$\frac{b^2}{S}=\text{Aspect Ratio}$$

My instructor asked me to obtain a wing span of 80-100cm. So I will have to choose Aspect ratio as well.


texts: What is a typical ratio of aircraft in air vs. total aircraft per airline?

texts:
While commercial airlines have a fleet of x aircraft, not all x aircraft will be in the air at any given time. Typically, several aircraft are in the air, some are on the ground (turnaround, loading, unloading, etc.), and some are in maintenance (not active).

What is a typical ratio of aircraft in air vs. total aircraft of an airline? I would be interested in airlines like Southwest, Hawaiian, Alaska Airlines, or FedEx. Can anyone provide some ballpark numbers on such a ratio?

(I assume this heavily depends on the type of airline, ratio of long- to shorthaul flights, budget vs. full-service vs. cargo vs. regional airline, number of total aircraft, route network, and obviously time of day (as some airlines do not operate flights during the night, or at least reduce flights during the night), etc.)


texts:
I see some very long NOTAM messages describing a whole section of arrival or departing procedure.

Is there a standard limiting how long a NOTAM can be? In computing I usually see limits in bytes, is there such a limit on NOTAM?


texts: What aircraft has the highest suggested landing speed?

texts:
Just out of vague curiosity, what aircraft has the highest recommended landing speed for an earth bound (atmospheric) craft?  And, btw, when I say "landing" I define it as thus:

Controlled
Powered (though if you want to note unpowered, feel free)
Safe, with the vehicle/aircraft fully recoverable
On a runway
On wheels or skids

I know there may be multiple answers, even with my trying to narrow it down, so feel free to list a few different scenarios.  I'm mostly wondering about planes that are in common usage though, both military and civilian (past and present)...  I'd have to think something like the SR-71 or MIG-25 would be very close to the top of the list, if not the top.


texts: What does the correlation between weather and midair collisions tell us?

texts:
The FAA's AFH states that "most midair collision accidents occur in good weather", in daylight, and nearby airports/navigation aids. What does this imply?

(One obvious explanation to this fact could be that there is simply much more traffic in this conditions, and despite a much lower accident rate per flight hour there are more overall accidents.)


texts: What drives the shape of an engine's intake on a fighter jet?

texts:
Rectangular intakes have more corners which might increase subsonic pressure losses and would weigh larger than a pitot (Semi-circular) type intake. Are the designer drivers solely based on supersonic pressure loss improvement? Or for area-ruling? Am I missing something here?

F 16 has a pitot (Semi-circular) type intake whereas JAS 39 Gripen has a rectangular one. I wonder why.

Edit: The question is in reference to a fighter aircraft intake which employ fuselage buried engine configuration in-contrast to wing mounted or externally integrated engines.
Fighter aircraft intakes are more complex when compared to simple cowl-lip configurations designed for larger commercial engines.
Intake shape,size,location are function of wide variety of parameters, so something must be influencing the intake entry cross section of a fighter aircraft configuration.


texts: Why does carburetor icing require manual attention by the pilot?

texts:
Why is it carburetor icing has to be handled manually by the pilot, at least in a helicopter? I am hoping very soon to take my PL/H lessons, I have a little understanding of mechanics and how things work and this is one subject that puts the willies up me as a potential student helicopter pilot. Why can it not be an automatic response built into the engine? After all, this is the 21st century.

Also, I am assuming every motorized engine is the same, so why does a helicopter require a manual response to carb icing but a motor vehicle doesn't? Do we not notice it because the vehicle is on the ground?


texts: How much does it cost to build a Boeing 737 NG?

texts: I don't mean how much is the list price. I am asking how much does it cost for Boeing to buy the engine, wing, etc. and put it together and ship it. What is the total cost of ordering everything and putting it together?


texts: In the US, what can be done at an airport when volunteering hours?

texts:
I am a 15 years old and need volunteering hours for my course work. I am a aviation enthusiast with knowledge of the industry and love for anything that flies. I decided to fulfill my hours at a local airport because I would be helping others doing what I love. I am from Florida, and I know this is the greatest place for all aviation related things.

The tasks I would like to perform at my local airport are fueling, taxiing aircraft in and out of a ramp, and help with other airport operations.

Is any of this possible?

If anybody can give me any idea on how to do this. I also like any advice to help me further my volunteering path with other aviation related tasks.


texts: Could maintenance data be downloaded via ATC facilities?

texts: Could aircraft send maintenance data to the airport via ATC facilities (e.g., tower, TRACON, enroute)? Or are they only used for air traffic control?


texts: Which languages are EASA exams and other documents available in?

texts:
Does EASA provide exams, documents and regulations only in English or in all the European Union Languages?

For example, I have to attend an exam for an EASA license. Can I do it only in English, or can I use another European Union language?


texts: Was there any kind of preventative collision training for dogfights during WWI and WWII?

texts: Watching some old films on YouTube about dogfighting has me curious about this. Definitely seems like most dogfights around this time were extremely close, involving tight formations and turns. Was there any kind of preventative collision training that the pilots went through around this time? Or was the goal just to get them through training ASAP?


texts: Is there any airport planning to install ILS CAT IIIc?

texts:
I know that right now no airport has an ILS CAT IIIc, but is there any airport in the world planning to have one in a near future?

Otherwise why bother to have rules and specifications for something not even planned to be in future?


texts: What is the feasibility of a Coanda/Magnus effect wing airplane?

texts: It seems the EU granted some hundreds of thousand € to a non-engineer, to study a cargo airplane with a turning cylinder in the leading edge, to produce increased lift by the Coanda/Magnus effect also used in the Flettner rotor sails for ships. As the concept seems having been discarded because of the important gyroscope effect of the turning barrel: anybody commenting about technical reasons for this revival of a discarded concept?


texts: What is that wing device that looks like a mini-spoiler on the CJ3?

texts:
The Cessna Citation CJ3 (model 525B) has that device circled below, what is it?

Source: airplane-pictures.net

I initially saw it as a mid-chord fixed spoiler-like device. As @programagor commented, it's parallel not perpendicular to the airflow.


texts: How is a horizontal stabilizer attached to the fuselage and works as a trimmable Horizontal Tail as well?

texts: I am trying to figure out how does the horizontal stab attached itself to the plane and moves up and down? Is the HS attached by the rear spar and to the fuselage?


texts: How to identify an aircraft from its NC- N-number?

texts: I have the numbers from the tail NC and then down is 4686N. Its a single wing prop driven multi seat aircraft. I am unable to locate it on the federal site, hoping I can get some info here again. Thanks, Ron


texts: What pitch attitudes are common during an emergency descent for an airliner?

texts:
What pitch attitudes are common during an emergency descent? I assume it would be a fairly nose-down attitude, but I can't imagine how steep would feel to the passengers.
Suppose a gradual decompression takes place and no structural damage is present nor suspected. What would be the pitch attitude for common airliners like the Airbus A320 or the Boeing 737?


texts: Can a few random interaction with cockpit controls result in a crash?

texts:
Lets say a monkey / snake interacts with 3 random controls inside the cockpit within less than 3 seconds until the PIC / SIC can take control of the aircraft again. Could such interactions result in a configuration leading to a crash that could not be reversed in time?

Assume the following:

small commercial aircraft (e.g. A319, CRJ900)
short distance flight (e.g. LEJ -> FRA)
appropriate cruising altitude for this distance

Edit: (for clarification)

It was mentioned I mixed the technical terms controls and instruments. I mean anything that does something when its pressed. So any buttons, switches, flight controls, etc.
This question is aiming at quick interactions with controls, no prolonged input.
Assume the pilots make no errors after the incident.

Background:
I was recently telling a post-9/11 flyer that I was generally allowed to visit the cockpit during the flight (as a child, pre-2000s). That person was surprised that this was allowed and asked what would've happened if a kid managed to interact with the cockpit.
Neglecting the fact that the pilots would probably intervene before any controls were touched it got me thinking if it would even be possible to doom a plane with a few quick interactions.


texts: How do I determine the maximum thrust that a Tesla powertrain (P100D for example) could produce if attached to a single propeller?

texts:
I am theorizing a drone helicopter from a tesla powertrain (P100D).
Lets assume the system is theoretically maximized with an optimum propeller (this is what I am currently stuck on).  How much thrust could a Tesla powertrain produce (I understand the thrust would decrease as the battery drains and voltage decreases, just wanting to get an idea of theoretical optimal thrust)?


texts: The ATC is unable to provide radar service to pilots, what's the standard way to inform this?

texts: Nowadays, ATC provides radar services to pilots, such as: vectors and surveillance, however, depending on the radar status, it can be out of service; on initial call the controller will inform the pilots about this issue, please, what's the right way to say this, using standard phraseology?


texts: From previous answers this is probably at RAF Duxford in the mid-1930s.


texts: Why does Airbus A380 have only reversers on inner engines?

texts: I have seen many videos, and I noticed that only the inner engine reverses were opened. Why not on the 4 engines?


texts: Why does an Avro RJ85 have four engines?

texts: The British-designed Avro RJ85 is a short-haul airplane with four jet engines.  What is the purpose of four engines for such a small aircraft?


texts: What is the MEL (minimum equipment list)?

texts: 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?


texts: How is it possible for supersonic aircraft to push air out of the way?

texts: If the force (pressure) can be transferred/propagated only at the speed of sound, how are supersonic aircraft able to move air out of their way/do work on the air? It seems that they must transfer the force faster than the speed of sound or else they would intersect with the air. Does the speed of sound increase at the shock to allow it?


texts: Should the type of plane influence my travel choice?

texts:
With those many websites that compare flights we usually have the opportunity to chose between different paths to reach the final destination.

Should the type of plane influence the decision? Ex. If I see that one company uses a Boeing 787 instead of a Boeing 767 or an Airbus A330-300, does that influence the travel experience in a perceivable way (In terms of turbulence attenuance, noise reduction, smoothness of flight, different types of landing/take off)?


texts: Can PC joystick simulate aerodynamic lock in spin?

texts: I never explored joysticks for playing simulators on PC. Can some kind of joystick simulate aerodynamic lock during spin? You do hands off control stick and it stays there, won’t center as usual. I understand that force feedback is often included in such products, but can force feedback override auto centering?


texts: Why did fly-by-wire systems take so long to implement?

texts:
The first commercial FBW airplane was the Airbus A320, which was introduced in the late 1980s. This system only worked after decades of research by American and European aerospace companies. If FBW only converts mechanical motions from an airplane's control yoke into electrical signals (along with sensor feedback), which change the aircraft's control surfaces, what caused FBW to be implemented so late, besides the abundance of computers even before the A320? Can someone also check my understanding of FBW?

My understanding of FBW:

Aircraft manufacturers use rotary encoders and potentiometers to translate mechanical changes in the control yoke into electrical signals.
The FBW computer(s) use feedback from the aircraft's sensors, and compare it with the pilot's input. A derivative based FLL system is used, perhaps?
Hydraulic valves/servo motors are used by the FBW system to change the state of control surfaces.

Thank you.


texts: Does the EASA LAPL(A) have a FAA equivalent?

texts: I have an EASA LAPL (A) fixed wing pilots license and would like to know what the equivalent FAA license would be.


texts: Does the PFD/ND XFR work when the PFD is on the ND screen on the Airbus A320?

texts: So I know the PFD has priority over the ND and that's why if the PFD screen fails its automatically switched to the ND screen. If the ND screens fails it does not get automatically transferred to the PFD screen because the PFD has priority. You can view the ND screen on the PFD screen by pressing the PFD/ND XFR button. So my question is if the PFD is on the ND screen because the PFD screen failed if you press the PFD/ND XFR will it show the ND information on the ND screen, and when you press it again it will go back to the PFD?


texts: Did older Airliners use a pitot-static system?

texts: Aircraft like the B707, how would the aircraft gather speed and altitude data? And if they used pitot static system by that time, was there ever anything else that gathered the speed data?


texts: What systems, in the cabin ceiling, when damaged could cause the masks to deploy?

texts:
I feel guilty when I chuckle at this incident.

Does anyone know what system(s) might be contained in the cabin ceiling which when struck by a high speed champagne cork could lead to deployment of the passenger oxygen masks?


texts:
I'm new to aviation but I am very passionate about it. I'm just 14 years old, so please help me in finding a good e-book about aviation for free.

I don't know how to search with Google about it.


texts: What special tyres (tires) are needed for high altitude takeoff and landing?

texts:
I just watched this video of AA922 taking off from El Alto (LPB) to Santa Cruz.  The video's author mentions that the aircraft needs "... special tyres" due to the high altitude.

While I do understand the physics and aeronautics associated with high altitude takeoffs (extra ground speed; longer runway needed, etc.), I'm curious:

What specific modifications to the tires (special or synthetic rubber, extra tread, stiffer sidewalls, etc.) are needed for high-altitude ground operations?
Should I assume these tires are the exception, not the norm, because of economics / higher prices / more maintenance?


texts: As a fairly new pilot who does a fair amount of x-country flying I find myself "feeling" safer going East at 5500 and West at 6500 happily burning extra fuel to get up there. Listening to the on route frequency position reports as I fly, I find the vast majority of GA traffic fly between 3000 and 4500 giving me the feeling that things are pretty crowded and less safe down there. Is there any validity to this?


texts: Can PPL, CPL, and ATPL be completed within a year?

texts:
It took me about 8 months to complete my PPL, because I struggled to go solo and I haven't started my CPL training yet due to financial set back.

I've heard about students who completed their PPL training in 2 months.

Is it possible to complete PPL, CPL and Frozen ATPL in 12 months and how do you go about it? And also, are there any cases? The one I've seen is 18 months.

Considering the fact that you have to write CPL exams, ATPL exams, IR, Night Rating, 100 PIC hours and other related tasks.


texts: How much does the horizontal stabilizer on a 737 move for one unit of trim?

texts:
Inspired by this question, what exactly is the meaning of a stab trim unit? Is it exactly one degree of stabilizer movement?

The 737 NG FCOMv2 (9.20.9 Flight Controls - System Description) only lists the ranges of the units:

  Stabilizer Position Indication and Green Band

  Stabilizer position is displayed in units on two STAB TRIM indicators located
  inboard of each stabilizer trim wheel. The STAB TRIM indicators also display the
  TAKEOFF green band indication.

  The trim authority for each mode of trim is limited to:

  Main Electric Trim

  flaps extended 0.05 to 14.5 units
  [737-600] flaps retracted 4.10 to 14.5 units
  [737-700] flaps retracted 4.30 to 14.5 units
  [737-800] flaps retracted 3.95 to 14.5 units
  [737-900] flaps retracted 3.90 to 14.5 units

  Autopilot Trim 0.05 to 14.5 units
  Manual Trim -0.20 to 16.9 units.

  The green band range of the STAB TRIM indicator shows the takeoff trim range.
  An intermittent horn sounds if takeoff is attempted with the stabilizer trim outside
  the takeoff trim range.

The full range of travel can be seen as a black arc in the following image (taken from this answer), which could be 17°, but it is hard to say from the image:


texts: How to deduce the dynamic general equations for a non-symmetric level turn manoeuvre?

texts:
I'm currently studying flight mechanics on a subject at my engineering degree and I'm trying to solve some standard case exercises with the general equations and diferent reference frames.
I've been able to solve multiple exercises on different looping manoeuvres enclosed in the vertical plane but I can't deduce the general equations for a horizontal plane.
$$ T
\cos\varepsilon\cos\nu - D - mg\sin\gamma-m\dot{V}=0\\
T\cos\epsilon\sin\nu-Q+mg\cos\gamma\sin\mu+mV(\dot{\gamma}\sin\mu-\dot\chi\cos\gamma\cos\mu)=0\\
-T\sin\varepsilon-L+mg\cos\gamma\cos\mu+mV(\dot\gamma\cos\mu+\dot\chi\cos\gamma\sin\mu)=0
$$

So starting with the above and taking into account some simplifications I get to an intermediate state which is quite similar to the solution for the problem which is the following:

$$T\cos\nu-D=0\\
L\sin\mu+T\sin\nu\cos\mu=\dfrac{W}{g}\dfrac{V^2}{R} \\
L\cos\mu-T\sin\nu\sin\mu-W=0$$

My question is: How is it possible that the Lift term appears in the second equation if the starting equation didn't consider it? And also, why the trigonometric relations for the thrust change?
(This results are for a non-symmetric manoeuvre).
I can't get in my mind why the general equations used in all the books can't give in a direct way the desired result without adding new terms.

Reference frame for the equations is wind-axis.
The angles used are:

$\nu =$ Thrust side-slip angle

$\varepsilon=$ Thrust angle of atack

As we are using wind-aixis reference frame:

$\mu=$ velocity roll angle

$\gamma=$ velocity pitching angle

$\chi=$  velocity yaw angle

$W=mg$, $T=$ thrust,  $D=$ drag, and $Q=$ lateral aerodynamic forces


texts: How did the service ceiling certification change in the 70s?

texts:
According to this video (at 4:30-4:45) the "later" Cessna T337 and P337 were limited to 20,000 feet whereas the older models "had no such limitation - a quirk in changes in the certification standards that took place in the 1970s."

What were these standards changes, and why? Did this have something to do with concerns about hypoxia? (For the record, I DO know that pilots use supplemental oxygen at high altitudes in non-pressurized aircraft.)

I'm assuming this video refers to U.S. regulations (i.e. FAA), but are similar laws in place elsewhere in the World?

Also, I have already read this question - it appears the FAA regulation prohibits exceeding the certified ceiling only if the POH says so (according to @pondlife's answer). I did not know that...


texts: Why would there be airflow from the back of a TAT probe?

texts:
During walk-around checks, I occasionally find airflow coming out from the back of the TAT probes on the Airbus A320. I wonder if it's air to cool down the TATs as they are heated during flight for anti-ice purposes.

I had a look at the description and operation of the TAT probes in the AMM but I couldn't find any information about that airflow and where it comes from.


texts: Is there a reason or code behind the Cessna model numbers?

texts:
Is there a story behind how Cessna model numbers were created?

E.g., models 170, 172, 180, 182, 206, 310, 336, etc.


texts: What is the relationship between mountain breeze and air pressure?

texts:
I am studying for my PPL and am having some problems understanding the mountain breeze phenomenon, especially when it comes to my understanding of pressure.

Basically, I've read that during the day mountainsides get warmer, resulting in the air flowing upwards. While at night this mechanism reverses : mountainsides get colder, and the air therefore flows downwards.

I could be ok with this, if I hadn't been told earlier on by my physics teacher, that in general high pressures tend to flow towards lower pressures. I.e warm temperatures flow in the direction of cold temperatures. This would imply that the breeze has to travel the other way around.

I can't really wrap my head around this. How can I reconcile both concepts ?


texts: What is the exact meaning of "manoeuvring" when said by ATC in reference to traffic?

texts:
In the UK, when receiving a basic service, sometimes the ATC unit passes traffic information. They may say it like this:

“Traffic to your three o'clock, similar level, C172 manoeuvring.”

What exactly is the word “manoeuvring” conveying? Is there a defined point where an aircraft is manoeuvring and when it is not?


texts: Is joining the air force a good way to become an airline pilot?

texts:
I've always loved the air force. However, my main goal is to become an airline pilot. Would joining the air force affect becoming a commercial airline pilot?

I am asking because if I join the air force, I am committed to seven years of service. Would this put me behind other pilots? Or, do airlines like pilots with military backgrounds?


texts: How would ATC try to establish contact with a VFR craft?

texts:
Example: I'm in a 172 tailed N1234A, on a pleasure hop between Hicks Field and Addison, circling around DFW International to the north, flying at 1500ft within DFW's Mode C veil under VFR (so I'm squawking 1200). The approach direction for the day also happens to be the north (this is common; prevailing winds in the area tend to be southerly). I'm staying outside DFW's airspace and therefore have not checked in with DFW Approach.

As I'm about to pass underneath "Area B" of DFW's space (which begins at 2000ft between 10 and 13nm from the airport sweeping across the northern approach), there is a 747 approaching low in the class B umbrella. It will pass above and in front of me, but still too close for their comfort, and so ATC wants to verify that I see the jumbo out my left window and perhaps suggest I descend.

Questions:

Was flying under the approach traffic of DFW my first mistake? Should I instead be heading around south (which would be a really big detour as I'd need to avoid Love Field's portion of Class B) or just contacting DFW Approach for clearance through Class B space?
Am I in the wrong for not having made prior contact with DFW Approach or Fort Worth Center in these circumstances, even though I'm operating VFR in class E/G space?
Should I even be this close to Class B in the first place (I'm 500 feet below it and 2 miles outside the surface footprint)? If not, what's a better altitude and range for me to have planned for? Outside 13NM from the airport, I'd be under Area H which starts at double my altitude, 3000 ft, but would also require me to enter or avoid Alliance's Class D space, and it'd take me quite a bit out of my way (since it's just for fun and logging hours, I might as well just touch and go at DTO if it'll be this much hassle to avoid DFW).
Would DFW or FW Center even bother trying to inform me of the situation, assuming I stay safely underneath Class B space and the 747 stays safely in it? One would think, being in contact with the 747, they could simply tell the jumbo to maintain minimum 2500 or 3000ft until 10nm out to maintain 1000ft minimum vertical separation, but my experience with boats says that if someone should yield right of way in this situation, it's the smaller craft (me).
Here are the title questions. How would DFW attempt to contact me? What frequency would I be expected to be tuned to? The emergency frequency is of course 121.5, but during normal flight along this path I could conceivably be listening to Fort Worth Center (122.65), DFW Approach (124.3), Addison ATIS or Approach, etc.
What would they say that I'd be expected to respond to, and how should I respond? I'm guessing they'd say something to the effect of "unknown VFR craft bearing 350 range 12 altitude 15, acknowledge and identify".


texts: Why Do Airlines Still Use Tractor-feed Printers?

texts: Why do airlines still use those old dot-matrix tractor-feed printers at their gate counters? I’ve always thought that was hilarious.


texts: Do you need strong muscles as far as applying the yoke is concerned, in order to be able to deal with some emergencies?

texts: In some of the plane accidents, the pilot had to use all his might to apply the yoke in certain direction to save the plane from imminent crash; in some cases even crew members had to help with the force. So it seems certain degree of physical strength is needed to be a pilot in view of possible emergencies, though it doesn't seem to be explicitly required?


texts: Is lift force less than weight during a descent?

texts:
In the above image lift is the same during a climb and during a descent. Is lift force not supposed to be less than weight during a descent?

Secondly, does descending at an airspeed much lower than the dive velocity (Vd) of the airplane affect the rate of descent of plane?


texts: How would SLP997 be calculated on a METAR? I understand that SLP117 say would be 1011.7 hPa, but I am sure that SLP997 is not 1099.7 as that would be impossibly high.


texts: Can pressurized aircraft be flown without pressurizing

texts:
Are there any pressurized aircraft models which can also be flown without pressurizing the cabin?

For example, if there were a short ferry flight, or a flight where the aircraft never got high enough for pressurization to be necessary, is it possible to have the aircraft remain unpressurized?


texts: How often does an autopilot update control surfaces' positions?

texts: How often does an autopilot update the position of the ailerons (or any other control surface) during cruise? Per second, per minute, or something else?


texts: Is there a difference between "aerobatic" and "acrobatic" flight?

texts: I hear and read both the terms "aerobatic" and "acrobatic" used to describe the more extreme maneuvers such as spins, rolls, loops and more. My questions is about the terms themselves. It seems that they are interchangeable, but is one actually more correct to use than the other? Why do we have these two very similar words in the aviation vernacular that seem to mean the same thing?


texts: Are three airports or four required for private pilot cross country?

texts: The cross country requirement for the private pilot certificate says that I need to complete a cross country flight of over 150 nm with full stop landings at three points and one leg at least 50 nm.  Does that mean three full stop landing points other than the primary airport, or three including the primary airport?  So if I take off from Airport A, fullstop land at Airport B, fullstop land at Airport C, then return to Airport A, is that good enough?  Or do I also need to visit Airport D for a total of three fullstop landings away from my primary airport?


texts: What is the true formula for parasite drag?

texts:
I found this site with formulas to calculate for the parasite drag. But I wondered if these formulas are to calculate parasite drag or the parasite drag coefficient? So do you have to multiply the calculated value with the square of the velocity, as in the formula for the general drag force?

I also wonder if there is a difference between the wetted area of an airfoil and the normal planform area?


texts: What factors besides tail/headwinds cause the time taken to fly some routes to be different from the time it takes to return?

texts:
I've observed this on many flight trackers; the time taken to fly from A to B is not necessarily the same as the time taken to fly back from B to A. Why is this so and what external factors besides prevailing winds (headwind going one way, tailwind the other) create this difference in time taken?

Example: late May 2015, per American Airlines, PHL to MCO is about 15 minutes longer going south than going north, but times MIA to BDL are essentially identical in either direction.  Prevailing winds would affect both routes similarly, but the difference in times northbound vs southbound isn't the same.  Why not?


texts: Why is the autopilot of the DHC-6 Twin Otter powered by bleed air?

texts:
I was just reading through the POH of a DHC-6-100 Twin Otter and was surprised to read the following:

  3.8.2 LOW PRESSURE - OTHER SYSTEMS. The airframe deicing system and
  the autopilot are operated by bleed pressure. In the event of a low pressure
  condition, a caution light on the caution lights panel will illuminate. Under these
  conditions, the pressure may be restored as outlined in paragraph 3.8.1. However,
  if increasing engine speed does not rectify the condition, the use of the
  autopilot and de-icer system should be discontinued.

(emphasis mine)

I understand why the deicing system is using bleed air, but why is the autopilot powered by bleed air? How does this autopilot work?

The following question is somewhat related:

How did old autopilots work?

but it never mentions anything powered by bleed air.


texts: What kind of antique WWI aircraft model is this? Inventor's prototype?

texts: I've discovered an interesting WWI era model of an aircraft and I am trying to find out what could it be. It is 29" long and it looks like not a hobby model, but an inventor's prototype. I love the idea of the extra fuel tank above the cockpit. It connects with a bigger fuel tank near the engine. Any ideas?


texts: What is this plane flying in overlapping circles pattern doing?

texts:
I have seen this Beechcraft Super King Air coming from France near Valenciennes and flying in circular patterns over a zone of Belgium for 2 days in a row now.
What is it doing, some kind of aerial survey ?


texts: FAA Knowledge Test Question Bank - What is the source of the actual test questions?

texts:
According to various online search results, the FAA test questions are not made  available to the public (page 6), but used to be.  Yet, question books claim to have the exact real questions.

How are the latest questions obtained?  I am aware of the sample questions the FAA provides, yet publications and online study sites claim to have "the most up to date" actual questions.

Are the questions available by FOI request?  Does the FAA provide the questions to publishers on some limited basis?


texts: How does a horizontal tailplane stabilize a cambered airfoil aircraft?

texts: The picture below shows the location and movement of centre of pressure when angle of attack is increased. Consider the aircraft is trimmed at the second airfoil in the picture. Thus the horizontal stabilizer has to provide a downforce to trim the aircraft. Now if the angle of attack increases, the centre of pressure moves towards the .25c point thus reducing the moment. If the stabilizer is still providing downforce, then the aircraft is unstable. How does the stabilizer give positive static stability?


texts: Do pilots of airliners and jumbos do a walk around preflight check for every flight?  How do pilots of large airliners and jumbos do sumping.  If its not a requirement because of aircraft design, why not implement the same design attributes to smaller and ALL other aircraft?


texts:
I've found similar autogyros on the internet, but not this one. Most autogyros appear to have 2 cockpits and this autogyro only has one.  Although I have matched its angle-tipped wings with other autogyros, I cannot match the configuration of the landing gear.  It appears that each wheel has a vertical strut to the wing and then two bars in a triangular configuration that attach to a center bar about 12" below the fuselage. The only autogyro I've found that appears to possibly be the same is in this video, but the craft's make and model not identified.

              The video is from California but I'm assuming my photo was taken in Wisconsin. I sincerely appreciate your assistance.


texts: What are these holes in the engine inlet?

texts: In the next picture can be seen within the housing, near the inlet:


texts:
Why are inlet cones of a lot of aircrafts conical. I read that it has something to do with slowing down supersonic airflow entering inside the engine. Is this true? If so, can somebody please elaborate on it?

Also why does supersonic airflow have to be slowed down before entering the compressor/combustion chamber. Does it cause engine flameout if not slowed down?

Also I've noticed that  the inlet cones of supersonic aircrafts are more pointy than that of subsonic aircrafts. Why is this so?


texts: Does an engine that combines an air-breathing rocket and non-air-breathing rocket exist?

texts:
Does a rocket engine that combines air-breathing and non-air-breathing modes exist?

The advantage would be it would have to carry a smaller tank and less oxygen, leaving more room for payload on a weight basis.


texts: Can an airline rewrite a flight's origin airport for the day, following an earlier diversion?

texts:
Suppose a domestic US civilian carrier regularly flies flight N directly from airport A to airport B, and flies back flight M from B to A.
Now, one day, the aircraft flying N is diverted to airport C, and the flight ends there (it doesn't continue to B).
Is it possible for the airline to have the aircraft fly from C to B and call that flight M? Even though that's not the route of flight M?
(By "possible" I mean "known to happen", "conceivable" rather than whether it's legal under FAA regulations, although that's interesting too.)


texts: What are the customs decal and eAPIS requirements for flying to the Bahamas?

texts:
I'm planning to rent an aircraft and fly to the Bahamas. I've got all the requirements including the Restricted Radio license.

However, there was another requirement which concerns paying of the Annual decal fee through CBP DTOPs and filling the form through eAPIS which kind of got me confused. Now I'm about to pay the annual user decal fee for a private aircraft but is this required if its a rental aircraft?

And could someone please briefly explain the difference between the two and how they should be used for my trip?


texts:
This is about the alleged "UFO" video. However, I'm not interested in speculation about what exactly the aircraft being tracked in the video is.

What is "autotrack" in an F/A-18 Super Hornet? Does it involve tracking by the radar, infrared, or digital interpretation of the video stream by a computer?

I've provided a link to the video. This shows the aircraft (the alleged "UFO") being "tracked" by what the pilot claims to be "autotrack":

As a bonus question, what is the other pilot asking about? He asks "Did you box a moving target?", what does it mean to "box" a moving target? Does it refer to radar tracking?


texts: Why is there no 100% power in the POH power setting table?

texts: I've flown a piper cadet arrow. The airplane has an engine of 200 horsepower at 2700 RPM. According to the power setting table in the POH, the maximum power we can set is 75% horsepower. With 100% power, we could fly faster (more fuel would burn though). Why doesn't the manufacturer provide the 100% power setting?


texts:
Let's say we are flying a piston engine high wing airplane (Cessna 172) that uses a carburetor.

What would happen when the fuel tank of a Cessna 172 became (partial) vacuum during horizontal flight?


texts: How dangerous would it be to start a jet engine with coins inside?

texts: With the multiple stories in the news of people throwing coins into a jet engine for good luck, I couldn't help but wonder how dangerous it would be if the act went unnoticed and the crew started up the engine with the coins inside. Would the engine be damaged? Would the damage be noticed before the plane throttled up for takeoff or left the ground? I'm sure the answer is, to some extent, "it depends", but what's a worst case?


texts: How is a composite fuselage repaired when structurally damaged?

texts: In case of FOD, a fuselage puncture for example, what is the repair process? Considering time, complexity and cost, how is compared if it was an aluminium fuselage?


texts: Where can I find a list of internal airline designations for various aircraft/cabin configurations?

texts:
Is there any way to tell what the internal designations of an airline mean? Looking at Delta's seat maps for the 757, Delta has a couple of kinds, but what's the difference?

Boeing 75A
Boeing 75M
Boeing 75S
Boeing 75G

I know they're slightly different configurations for different routes, over water etc, but can what type is used on what route/configuration or what the designations mean be found somewhere?

Is there a place where these are defined for airlines of the world?


texts: Has the FAA ever granted a LODA for compensated instruction in a non-LSA E-AB?

texts: I have been trying to find a list of granted LODAs to get this question answered. No joy. I am considering purchasing a Sling TSI E-AB. It would be great to be able to instruct in it for compensation.


texts: How does an operator change the engine thrust rating?

texts:
If, for example, an operator has a Boeing 737-800 with CFM56-7B engines set at a 22K thrust rating, but the next operator wanted to operate the engines at 24K thrust rating, what would they need to physically do to the aircraft in order to change this?

Would it involve the engine going to the shop for certain components replacement, or is it as simple as a FADEC reprogram? I've noticed the life of certain engine components differ depending on the thrust rating used so I wondered how the engine is converted to these different configurations?


texts:
I have been making an AI ATC for a game I have been writing. The channel is mostly dead air but occasionally you can hear some chatter:

http://reskin.us:8081/stream

I am a former airline pilot and a few scenarios come up frequently in the game which I don't have experience with in RL (luckily):

1) Aircraft flying through the class B without talking to approach

2) Aircraft establishing communication with ATC when already inside the class B

3) VTOL operations - to separate aircraft I understand they fly a very normal approach to the airport but then are treated like rotorcraft after that? Do they hand you over to ground control when you are over the numbers or how is that coordinated?

Any controllers out there know what they would say in these cases (if anything) over the radio?

Thanks!


texts: Are there downloadable versions of the Canadian VNC and VTA charts?

texts: Are there PDF versions of Canadian VNC and VTA charts available for download? I fly in Australia where airservices lists them on their website so I was hoping to find something similar for Canada.


texts: Can a passenger jet be towed to safety if it breaks down in midair?

texts:
A car can be towed by a tow truck to the repair shop when it breaks down on the highway. Is it possible for a passenger plane to be towed by an emergency tow plane along the air corridor to the next nearest airport assuming it cannot reach there on its own power (example if it runs out of fuel or both pilots are incapacitated)?

Update:
This question actually consist of two parts. Whether it is feasible and whether this is practical. I have seen a small tugboat towing a barge; a man pulling a firetruck. Before writing off this idea completely, can someone address what's stopping a fighter plane from towing a passenger jet if a proper point of harness is installed?


texts: On an average, space of how many economy class seats is taken up by a suite?

texts: The suites offered by many airlines for the super rich, are very spacious and convenient. Though, I can only Read about them! One thing I can see is, the A380 is capable of upto 853 economy only passengers, but most of them carry 500 economy, 65 business and 12 suites. So, they must be eating some considerable amount of space. What I am asking is, basically the number of economy class seats that would fit inside a first class cabin and not how much space is available for first class and economy class cabins.


texts: When flying to a towered airport when the tower is closed, what frequency should I use?

texts: The attached picture shows the Rapid City Regional Airport, KRAP.  If I arrive after KRAP's tower is closed, which frequency should I use: 125.85 or 122.95?


texts: Flight Design CTSW vs Cessna 162 (Light Sport Airplanes)

texts:
I am going to buy a light sport aircraft in next couple of months and trying to make a decision between Flight Design CTSW and Cessna 162.
I have some budget within 50K and want inexpensive plane.

Flight Design CTSW (not CTLS) pros and cons:
I like its design and I like Rotax 912, but I am afraid of maintenance cost of rotax, parts and mechanics availability.

Cessna 162 pros and cons:
Looks like a little bit cheaper to buy. I like parts availability and mechanics. I don't care about that it burns more fuel and heavier.

Does anyone have some experience with one of these planes or would recommend a different make and model? (LSA only in USA). Thanks.


texts: Can balloons be stacked in a climable daisy chain to the edge of space?

texts:
How high can a balloon/s be and still be tethered to the ground?

The most common problem was finding the calmest place on Earth.

The longest balloon chain is 20 km

Pictures below are basic balloon chains.


texts:
I'm an aviation enthusiast (I do not, nor have I ever worked in the industry), and after researching several various emergencies (reading text documents, reviewing CVR transcripts and watching documentaries and TV shows such as Air Crash Disaster/Mayday), I'm curious as to why so many spatial disorientation situations have resulted in the loss of aircraft.

My thinking is that even if there is zero visibility combined with possible instrument failure causing disorientation, why don't aircraft have a simple glass ball half-filled with water set atop the console?

Wouldn't that provide a crude but reasonably accurate aircraft attitude? I mean:

water is at the top of the ball (ie. toward the ceiling), plane is inverted
water is angled toward the left of the ball, plane is banking left (similarly for right)
water is angled forward, plane is nose down
water is angled aft, plane is nose up

Even if a/both pilot(s) were fully disoriented due to whatever situation to the point they believe their attitude and other instruments aren't jiving with what their balance is telling them, a quick look at such a simple device would at least indicate a reasonable measure of sanity, wouldn't it?

Now, water might be too viscous a fluid for this, but replace with an oil or similar to minimize movement due to vibration etc.


texts: Aircraft with load sensors in their undercarriage to calculate CG

texts:
In another question on SE aviation I read that certain aircraft have load sensors in their undercarriage to calculate CG. Which are these types?

  The technology to build load sensors into the undercarriage is
  available and it appears that a few planes are equipped with it.

PS. I don't mean just the weight on wheels sensor which is more a switch than a measurement.

Would an accurate weight of a loaded aircraft be helpful?


texts: Why should I not use a "lifting tail" on my ultralight design?

texts:
In my misspent youth I designed and built many rubber, gas, and RC models. When I wanted good climb and glide I used a aft CG [60 to 80%] and a lifting tail. I had no stability or control problems, though CG was critical. I'm a 75 yr old retired air traffic controller, pilot, flight instructor, A&P mechanic who would like to get his feet off the ground again with a flying wing or tandem wing ultralight.

I don't need speed, but I would like to climb in thermals and ridge lift.  So far a flying wing like the Monarch with 15 to 20hp and a wing loading under 4.5 lbs/ft. and a span of 30/40ft sounds good.  With two lifting surfaces I might keep span under 25ft with a good aspect ratio. Please try to keep answers in laymen's terms.


texts: What is a good flight simulator for a beginner?

texts:
I'm in the UK and I wish to learn to fly starting with a home computer simulator.
I have never flown and I am only interested in light aircraft. I need instruction from scratch: what the instruments are for, starting the aircraft, everything from the very start.

I need someone to recommend to me a good home computer simulator which comes with basic flight instruction.


texts: During a touch and go (C150) should I first raise flaps or set full throttle?

texts:
I am now finishing my PPL (on a C150 in Czech Republic) and today had quite a close call when doing a solo touch-and-go on a short runway. We train on grass (and therefore rarely completely level) runways and take off with flaps 10 (landing with 20 or 30). I stayed in ground effect a couple of seconds before touchdown and then, according to my instructor's (hmm) instructions, first raised the flaps to 10 and then applied full throttle (and carb heat full cold).

I saw trees approaching and cleared them by an uncomfortably small margin (which made my further way back on which I managed to lose track a bit seem like a joke I wouldn't care about).

The explanation I heard from other flying guys is that touch-and-go should be an imitation of landing followed by a take-off, and one should therefore retract flaps (to 10) and then apply full power. And if you are not sure of runway distance left, you should make a full stop and take off anew.

Does this actually hold true? Imitation and practicing is all good and well, but assessing the runway distance left (and more so at an unfamiliar unlevel grass field I was landing at) in one second you might have may prove too risky and may lead to quite different consequences I was lucky to have avoided.

The instructor actually confirmed they were planning to change their route for the long nav flight because this field proved too challenging.

The question is, however, generic: first raise flaps or set full throttle?


texts: Is there any difference between Airbus and Boeing on yaw damper technology?

texts:
Modern aircraft have yaw damper systems installed. Is there any difference between the two big manufacturers on yaw damper systems, such as the location, etc.?
I have to do some research on this topic and haven't found any answers yet.


texts: What airport has this walkway over a taxiway?

texts: I saw this image posted in another question. What airport is this?


texts: Would a 737 pilot use flaps in nose dive?

texts: Since flaps help lift the plane, would they deploy flaps if the plane was nosediving? And what would they do if the back pressure was too much? I know speed increases lift, but can full throttle make the plane difficult to level out?


texts: Does an overhaul reset the 'life limit' of a turbine engine?

texts:
I've come across a very unclear maintenance document.  It's often referred to as a "Hard Card" for an Engine Axial Compressor Turbine.  This specific part happens to come from a French manufacturer, so there may be a language barrier issue involved, but I'm trying to determine if anyone has clarified documentation that discusses this issue.

(Source: helisupportnz.com)

On this card, beneath a section translated as "Available Life", "Module Life Limited Parts", and "Usage Limited Parts", there is a section translated as "Time for the Calendar Limit".  Next to this is another section translated as "Date for First Entry into Service" and a logical third calculated section translated as "Limited Date for Usage".

These connect with each other very clearly and easily.  For example, one card marked with a 15 Year Calendar Limit is showing a Limited Date for Usage of 2020 when the Entry into Service was 2005.

I have a maintenance technician who is under the impression that this Calendar Limit is reset after every Overhaul of this Engine Module.  Unfortunately, no where in this card does it say that this is the case, and if this module gets reset when it is actually a Life Limit, then we will run into an overfly.

Has anyone come across this and received a clear answer from someone in authority over this?


texts: What should I look for when choosing a kneeboard?

texts:
There's a lot of variety in kneeboards. Some pilots fly with an improvised one: just a small clipboard with some scrap paper on, with a strap glued to the back. At the other extreme, fancy ones come with pen loops, pockets, and maybe even a fold-out area big enough to rest a map.

I'm not looking for a specific recommendation: I'm looking for how to choose. If I decide to make something homebrew, what should I bear in mind? If I buy a commercial product, which features are actually useful and which are "box features"?


texts: How does the electrical system in a light aircraft such as a Zenith CH-750 or Cessna 150 work compared with electrical systems in larger aircraft? Are the system is different than the electrical system on a common car?  Do we need static electric discharge system?


texts: How are turboprops and other propeller planes pressurized?

texts:
I know how most turbofan jets are pressurized:

But it can't be the same with turboprops, as I don't understand how propellers can take in the air. Yet, planes like Q400s can fly above 8000', all the way up and higher than FL220!  Can somebody explain how this is possible?


texts: How can the range of an aircraft be calculated given real wind conditions?

texts:
I am very new to aviation and trying to understand how to calculate the actual range of an aircraft given real world wind conditions.  I understand from this related question that you need  30 minutes of reserve and that tailwind and headwind direction will obviously impact your range.  I've also heard that the altitude you fly at can impact your range because higher air is thinner and allows you to travel faster.  I also would assume that the aircraft load would impact range.  So my question is:

Given the theoretical range of an aircraft (i.e. from specs published at this site) how do you calculate how far the aircraft can actually travel at a given altitude, with a given load, and with current wind conditions?


texts: Why do pilots wait for a positive rate to put the gear up, When V1 means “commit to takeoff”?

texts: To explain further, V1 means they cannot stop in time if anything happens. Therefore they must commit to taking off. So why wait for a positive rate? Shouldn’t it be retracted as soon as they see a difference in altitude? From my understanding, is that the landing gear deployed during a crash landing can rupture the fuel tanks??


texts: Why did AF447 never return to normal law?

texts:
Air France Flight 447 degraded from normal law to alternate-2B law when its pitot tubes were temporarily filled with ice crystals, resulting in a loss of airspeed data.  As a consequence of being in alternate-2B law, most of the aircraft's flight envelope protections were lost, allowing the first officer to stall the aircraft with his counterproductive control inputs, causing the aircraft to experience unplanned high-speed hydrobraking.

However, according to the BEA report on the crash, after only about a minute, the pitot tubes had unfrozen, and all airspeed data was once again valid.  At this point, the aircraft was still climbing, and, although its airspeed was steadily bleeding off, it was still approximately 30 seconds away from stalling (although it was still dangerously close to doing so, and the stall warning horn was sounding); had the aircraft automatically returned to normal law, with all its associated envelope protections, the aircraft would have rapidly recovered itself from the impending stall.

And, yet, despite the clearance of the fault that had caused the aircraft to fall from normal law to alternate-2B law in the first place, it did not transition back into normal law at this point, instead remaining in alternate-2B law all the way up (or down) until impact occurred over three minutes later.1

Why did AF447 remain in alternate law, even after airspeed data from all sources was once again valid?

1: Once the aircraft actually stalled, the airspeed data once again started being invalid (interspersed by periods of validity), but this was due to the aircraft's extreme attack angles during its descent, and would have been avoided had the aircraft not stalled.


texts: What are the advantages of the NASA LEAPTech propeller on wing technology?

texts:
NASA has detailed experiments with a new type of parallel array of small electric propellers on the leading edge of the wing technology that they are calling LEAPTech.

The press release notes that the benefits include: "Each motor can be operated independently at different speeds for optimized performance. Key potential benefits of LEAPTech include decreased reliance on fossil fuels, improved aircraft performance and ride quality, and aircraft noise reduction."

A Popular Science article notes that: "When complete, LEAPTech’s planned cruising speed will be 200 miles per hour, with a range of 230 miles on electric power and 460 miles when running as a hybrid. The tremendous and immediate lift generated by this octodecaprop plane and its mere 31-foot wingspan means it should be able to take off from runways as short as 2,000 feet, which is a good 700 feet shorter than the FAA recommends for small passenger aircraft."

Is  this related to a spinning wing (Magnus effect) or do the benefits accrue from some other aerodynamic effect? This appears to be a technology that would only benefit very small aircraft and would not be scalable, is this correct?

[Photo credit: NASA]


texts: Why is an accident referred to by flight number instead of registration number of the airframe?

texts:
Most accidents are referred to by flight number, for instance MH17 or MH370 to name a few recent ones.

Flight numbers are usually but not always retired after a crash. So why isn't referred to the registration number instead?


texts: Is multi element wing good option for slow flight airplanes?

texts:
Can we use  multi element wing  for slow flight planes, like F1  multi element rear wing?
If we know that pressure act prependicular to the surface why this two upper elements are "almost" vertical?
It seems to me that they produce "tons" of drag instead lift.Resultant  force point to far back,instead down!


texts: Is it possible to build a turbojet engine with aluminum cans? (Soft drink cans)

texts: I'm interested in building a working model of a turbojet engine, but I don't have a lot of supplies. So I'm wondering if it's possible to use aluminum cans for construction, for every body part. While we're on this topic, would the heat melt the aluminum?


texts: What is the difference between “affirm” and “acknowledged”?

texts:
Recently, I've watched Air Force One and I heard ATC and the pilots say "Acknowledged." instead of "affirm" or "affirmative" as I've learned..
Is it common to say both? Or might "Acknowledged." just throw the controller / pilot off?


texts: Why would an aircraft drastically reduce in speed and then accelerate during landing?

texts:
I was on a flight today and I noticed that as we were approaching to land, the plane drastically reduced its speed for few seconds and then regained its speed.

Can somebody tell me why?


texts: Can a registration number be reused indefinitely?

texts:
This answer highlights the fact that some registration numbers can be reused (here F-WZFD as a temporary registration number for newly built aircraft and 9V-SMF for a commercial airliner). This made me wonder how many times registration numbers can be reused and the existing constraints to reuse a registration number.

Is there a limit for the number of time a registration number can be reused?
Is there a minimum time between the decommissioning of an aircraft and the reuse of its registration number?
Are there registration number that cannot be reused?

I'm interested by all ICAO's member but if needed, the answer can be narrowed to the jurisdictions covered in the linked question, namely Singapore and Europe.


texts: How do I find a plane's history when booking a flight?

texts: While booking tickets for a commercial airliner, is it possible to know the name of the aircraft (not the model, but the designated name) and then search the history of the plane, on how old is it, how many repairs has it gone through, has it ever had an accident etc.


texts: What exactly is the afterbody of an aircraft?

texts:
In my understanding the afterbody is everything trailing behind the nose of the craft excluding the wings and fuselage, and will thus include the empanage.

What exaclty is meant by the afterbody?


texts: What is the difference between a monocoque and semi-monocoque fuselage type?

texts: What are the main differences between these two types of fuselages?


texts: What happens when VFR conditions change over a longer flight?

texts:
If I am understanding correctly, you're not really supposed to use VFRs if the weather is not clear enough that you can ensure you're not going to run into things. Usually you do this by looking at the weather reports around your route and going "nice and sunny, VFR should be fine". Then picking an altitude that meets your other needs, but keeps you out the clouds (if there are clouds).

Then, because you are flying VFR, when you're outside of certain air spaces, you're "on your own". No ATC, or things like that. Maybe some flight following, where the ATC guys goes "Ummm, you see that big mountain right? you're not going to hit that are you?" But also no guarantee of that either (because you're supposed to be using your eye balls to see that you don't smack into the mountain).

But what happens when conditions change, either because the flight is taking longer than expected, or because they just do, and stuff happens? You seem to be in a rough spot. You should not continue your flight using VFR, but you can't land. So what do you do, specially if not rated for IFR flight?

Specifically, conditions are no longer acceptable for VFR flight, and you're not really near your destination, and the smaller airports around you are not currently staffed.


texts: What are these numbers visible from the runway at Narita airport?

texts: At Narita Airport on the terminals there are big digital numbers visible from the runway. They aren't in some reliable order- I saw 98,91,93,95,97,99. Maybe they are Aerobridge numbers. I didn't get a photo as I only had my mobile which was off during taxiing. What are they for?


texts: How do wing tip vortices that interact with the wing surface affect drag?

texts:
Often people say vortices are behind the wing so they cannot produce drag, I am not interested in those vortices behind the wing....
I am interested how wing tip vortices which interact with the surface of the wing affect drag and does it make sense to reduce the area of wing tip, because of them?

Wide vs narrow wing tip:


texts: How can the Antonov AN 225 only have 2 nose wheels?

texts:
I was watching the video of the AN 225 unloading at Perth airport this weekend, and it suddenly occurred to me that there are about a zillion rear wheels on the aircraft, yet only 2 nose wheels?

This might make sense in a normal airliner, but in this one, the whole weight of the 117 Tonne generator is passed over the front wheels, as it is unloading?


texts:
Is it possible for aircraft to transfer from low to high airways?

In the US, you must be flying below 18000 feet to be able to use a Victor airway, while you must be at FL180 or above to use a Jet airway.

If it is possible to do so on one flight plan, at which point would you switch over, and what altitude would you need to be at?

I've looked at various low and high altitude enroute charts, as well as FAA guides on using these, but they don't seem to really point this out.


texts: What are "ground-based navigation systems which provide vertical guidance" and how do they compare to altimeters?

texts:
I am a total layman when it comes to aviation but for a school presentation I am trying to understand the reasons why Air Canada 624 crashed while trying to land on runway 05 at Halifax (CYHZ). I have read the investigation report and the press release the Air Canada pilots union have published. The press release says:

  ACPA strongly advocates for all major airports to have the necessary
  equipment to offer both lateral and vertical guidance and high
  intensity lighting to allow pilots to orient aircraft for landing.

  Many runways at Canada’s largest airports lack the ground-based
  navigation systems which provide vertical guidance – that is, the
  distance between the aircraft and the ground – to orient an aircraft
  for landing.

I was under the impression that an altitude reading is always available through the radio altimeter or the barometric altimeter.

Why would such a "ground-based navigation system" that provides "distance between the aircraft and the ground" be needed? What can it provide that the regular altimeters on board cannot provide?


texts: Where can the highest air density be found on Earth?

texts:
I would like to see if there is any possibility of testing, validating and actually demonstrating a potential design for drag-mediated rapid braking of an ultralight plane - possibly a solar plane. In reality, a drag coefficient is not really a constant - it varies with both density and speed.

Tests at low density can be done using altitude, but for the highest density points, I am not sure even what densities are ever available anywhere, and how to go about finding these locations.

At first I thought - Death Valley or the Dead Sea area at night, but they can still be fairly warm.

Then I thought the south pole is really cold but then I realized the altitude is quite high.

Then I thought flying over some arctic or antarctic area near sea level would be the highest density, but water can warm the air a bit.

Is there a known place where one could fly through the highest density air on Earth? Is there a world's record? I suppose one could at least analyze historical airport data, but you'd need temperature, pressure and humidity and synthesize a density.

Assume the craft is actually flying and has a pilot on board - no environmental chambers, wind tunnels or mine shafts.


texts: What is the voltage and amps on the transformer rectifier?

texts: On the Airbus A320 ECAM electrical page there are two TR or transformer rectifier and they convert AC or alternating current electrical power into DC or direct current electrical power. But on the ECAM it shows that TR has Volts and Amps but what are they? Are they the new DC current coming out of the TR or the AC current entering the TR? On the subject of Electrics, what even is AC/DC BATBUS and what is there purpose?


texts: How does the traffic pattern at a large airport affect nearby, smaller airports?

texts:
Do the landing and takeoff directions for a smaller airport (GA and bizjet traffic) change when the traffic direction at a nearby large airport changes?

Specifically, I'm wondering about how traffic at FTY and PDK would be affected by the direction of traffic to/from ATL.


texts: Why do we need to starve the engine before turning it off?

texts:
This question is for Piper Tomahawk, but I guess applies to any small aircraft.

Why do we need to use the fuel mixture to starve the engine before turning it off with the key? Why can't we just turn it off with the key like in a car?


texts: Would a ducted fan with a nozzle like a jet engine have more thrust than a normal ducted fan?

texts:
I'm trying to design a miniature ducted fan engine for a small project, but I'm not too sure how much contraction should happen between the fan and the end of the engine, if at all.

Engines like this  or this look like they have very little contraction at all, but why not use the pressure created by the fan and contract the space making the output velocity higher?

This is the same sort of principle behind the bypass air of a turbo fan engine and I don't see why not to use it.


texts: What is the cause of Wingtip Stalling? Why do sweptback wings have a tendency of stalling at the tip?

texts: I am a beginner in Aircraft aerodynamics. I have read about the disadvantages of wingtip stalling and the fact that sweptback wings have a greater tendency of stalling at the tips and forward swept wings don't. However, I don't know what causes it to happen. Is it something to do with the direction of airflow from root to tip and vice versa?


texts: Do we artificially add a smell to jet fuel?

texts: Many dangerous liquids have odorants added so that you can know if something dangerous is leaking.  Is anything added to jet fuel (such as Jet A-1) to give it a distinctive smell?


texts:
Here is a Scenario:

PF: Flaps one.
PM: Speed Checked, Flaps one.

What does that mean and why do they have to say "speed checked" every time?


texts: Does the FAA have regulations for aircraft that carry passengers over large oceans regarding number of engines and flying range of the aircraft ?


texts: Are there any guidelines on airframe age and metal fatigue in light aircraft?

texts:
Are there any guidelines or rules of thumb about when airframes become affected by metal fatigue?

More specifically, is something like a 1950s vintage Cessna still safe, or should I be worried about metal fatigue? I'm thinking of buying and completely overhauling a C172, but how can I determine if I should be concerned about metal fatigue or not? The planes are so old, and it doesn't seem possible to me that their structure has not been compromised because of their age.


texts: What's the right way to take a dog in a small plane?

texts: 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?


texts: Do I have to take science in high school to become a pilot?

texts:
Some articles say we don’t need to take science in high school to become a pilot but some say we do... It’s very confusing and I don’t know which subject to take; Science, commerce or arts.
Hope someone can help.


texts: Attempting to determine whether a flight took place

texts:
We had some houseguests recently who were scheduled to take American Airlines flight 2953 from SAV to ORD (May 16, 2019). They called and said that there had been a mechanical problem with the plane and that the flight had been cancelled. Since I had the flight information, however, I had already been tracking the flight status, and I saw that the plane was still scheduled to depart, and then I saw that it had taken off and landed, albeit with a delay. (The guests came on another flight the next day.)

I didn't confront the guests, of course, but I am curious to know whether there is any possible explanation for the discrepancy (i.e., other than that there was some other reason for the delay that they didn't wish to share with us). Could the flight have been cancelled and then rescheduled without their knowing it? Could the plane have been returned to ORD without passengers, and it showed up on the flight tracker as the regularly scheduled flight? Or is there some other possibility?


texts: How are STCs granted for similar aircraft? Archer vs Arrow

texts:
I'm specifically interested in the Garmin GFC 500 autopilot certification, but this question can apply to any STC question.

The GFC 500 is certified for a ton of Archer (PA-28) variants, but no Arrow (PA-28R) variants, and Garmin doesn't seem to have any plans to certify the Arrow. Since the Arrow (201) and Archer (181) are the same airframe, the only difference between them is the engine and the landing gear as far as I can tell. Why would the work put into certifying the PA-28-181 not basically cover also certifying the PA-28R-201?

When getting an STC, do you have to start the entire process from scratch for every variant of every aircraft you're trying to get an STC for?


texts: Can a U.S. President have a non-government owned aircraft that would routinely be given the call sign AF1?

texts: Can a US president use a personally owned jet with the call sign AF1? Would the Air Force be obligated to add security and defense measure to this aircraft if the president refused to fly in the VC-25?


texts: What noises can you hear as a passenger?

texts:
I'm just curious as to what the noises are that you can hear as a passenger in the cabin of an airliner?

For example (ignore the crew talking), the noise at 7:09 - 7:30 on this video; is that the flaps?

What other sounds might a passenger be able to spot?


texts: Can someone please help me identify this?

texts: I apologize for the image quality as it is a picture of an image on a television screen.  I was watching an episode of American pickers at the time and the model of the plane was not discussed.  Can anyone identify this aircraft?  I am not sure I have seen a configuration like it before.


texts: Why does a jet engine acquire a metallic whine when in full power?

texts:
I had a flight yesterday on an AA Embraer ERJ-190. As the plane idled at the end of the runway there was the familiar high-pitched jet whistle, which increased in pitch as the engine started spinning up. But, when it reached full power, the whistle was joined by a far-lower-pitched metallic whine, which persisted until the pilot throttled down after the initial steep climb.

I've heard this before on some (but not all?) planes. By ear, the whistle was about four an a half octaves above the whine, which is about a factor of 24 (I may have been off by an octave, or another factor of two).

On a past flight I calculated that if the main fan spun so that its outer edge was moving at the speed of sound, the whine would be at about the rotational frequency of the fan. If the fan had 24 blades (or 48 if I have the wrong octave) then the whistle could be the fan blades, and the whine the fan itself.

One explanation could be that there's something asymmetrical about the fan, e.g. one blade is a bit too long and hits the housing when at full power. (Of course, this would make no sense from an engineering and reliability standpoint.)

What causes that far-lower-pitched metallic whine?

Edit: I just returned on a JetBlue flight, but also using an ERJ-190. Where before I was seated in row three, this time I was in row 24 of 25. On takeoff, there was only a loud roar; no "whine" or "whistle". So, it's pretty clear that the noises I'm referring to above are emitted from the engine intake.

And, on this page I found a photo of the ERJ-190's GE CF34-10E Efficient Engine's inlet:

Sure enough, the intake fan has 24 blades. So, my above guess on the frequency ratio between my "whine" and "whistle" has some physical basis.

And, I'd like to respond to a comment by @kevin:

  Could it be that the "whine" always exists in the frequency spectrum, but it's just below our human ear detection threshold (both pitch and amplitude) during low rpm operation?

When the "whine" starts and ends, my impression is that yes, the pitch rises as it initially strengthens, and falls as it finally fails. However, its volume is strongly pitch-dependent, so that it is far quieter when running at 80% of the maximum pitch/RPM, and inaudible below that. It sounds as if that blade which purportedly hits the housing only does so above a certain RPM (again: this is what it sounds like, it almost certainly is not what is actually happening). More generally, my interpretation is that the cause of the "whine" only happens above a certain RPM.

Edit 2: @fooot was kind enough to point out another question that is basically a duplicate. My text and suppositions are (I think) a lot clearer, but the other question links to two videos that demonstrate exactly what I've been talking about:

Airbus A320 with IAE V2500 engine
Airbus A320 with CFM56 engine

Neither of the answers to the other question are correct; one focuses on the fan blade noise (too high-pitched) and the other on pressure equalization vents (not engine-speed related).


texts: Why is best angle/rate of climb indicated in airspeed?

texts:
I understand the difference between best angle of climb $V_{x}$ and best rate of climb $V_{y}$. When I take off I would aim to maintain one speed or another depending on what I want.

But I don't understand why it's measured in airspeed, instead of pitch angle, which would seem more intuitive.