texts: Do propeller planes give contrails like jets do?

texts:
Last weekend, while watching the second world war film "Fury" with a friend, there was a scene near the end with a large set of bombers flying overhead, leaving large contrails. That seemed wrong to me, as I'd thought that contrails were a jet thing, but the friend I was watching it with thought it was right. (Was a lovely shot though, accurate or not!)

That has me wondering - do propeller planes generate contrails like jets do? And if so, is it only turborops that would, or is it something all propeller planes can create?


texts:
In a recent BBC article regarding the disappearance of Malaysian Airlines Flight 370 (MH-370), the writer refers to a US Naval officer's statement:

Commander William Marks from the US Seventh Fleet, which is taking part in the search, says he expects the plane's flight recorders to be floating in the water.
"In calm seas, if there were a soccer ball [football] or a basketball floating in the water, the radar could pick it up. They [flight recorders] typically have a radio beacon and so for example our P3 [radar] - if they are flying within a certain range of that - will pick up that radio beacon. We have not yet picked up anything, but that's typically what those black boxes contain."

I was under the (potentially incorrect) impression that flight recorders, by nature of the materials needed to protect their contents in the event of a crash, are quite dense and unable to float in water. I base this impression on news reporting of other airliner crashes (such as Air France 447, which crashed in the Atlantic), where the recorders were found some time later on the ocean floor.
Additionally, it seems reasonable to me that one would want to have the recorders not float so that they would come to rest near the other debris on the ocean floor since the recorders are equipped with underwater locator beacons which would aid in locating not only the recorders themselves but also the debris of the plane. If the recorders floated then they could move significant distances from the crash site and other debris, complicating search efforts.
It seems that Commander Marks, the writer of the article, or I (or some combination thereof) misunderstand something about flight recorders and their behavior in water.
My questions are these:

Do flight recorders float on water? If so, why?
I know that flight recorders are equipped with underwater locator beacons. Are they also equipped with radio beacons (either an active transmitter or a some passive device like a corner reflector to make them easier to detect with radar)?

Edit: The article has been updated, with the section regarding floating data recorders now reading:

Commander William Marks from the US Seventh Fleet, which is taking part in the search, said he expected the plane's flight recorders to be floating in the water.
He said the recorders, also known as "black boxes", are fitted with radio beacons that can be picked up by radar.


texts: Airspeed Calibration alternate static source, what is this for?

texts:
I found a 'Airspeed Calibration Alternate Static Source' Figure in C172R POH.

There are three kinds of Figure,
1. Heater off, Vents and Windows Closed
2. Heater On, Vents Open and Windows Closed
3. Windows Open.

What are those figures for?


texts: Is it practical to become an airline pilot in order to travel internationally?

texts:
I am a person with very diverse interests and a lot of life goals I want to achieve. One of them is becoming an airline pilot (just working as one for a year or two) and the other is traveling the world.

I would like to combine two goals in one, that is becoming an airline pilot after I finish college and travelling the world at the same time, i.e. flying intercontinental flights.

So, my question is basically this: Is it possible to learn to fly and become an airline pilot within about 3 years (let's say age 20-23), then immediately get employed as an airline pilot and fly intercontinental routes (even as a co-pilot)?


texts: Which simulator is appropriate to learn the minimum to land an airliner?

texts:
If one has zero flight training, but wants to learn the basics, so that they might be able to land an airbus in a Helios 522 type scenario (or any double pilot incapacitation for that matter), what would be the best simulator to learn on and what specifically would be best to learn (basically how to communicate with ATC and perform an auto-land).

I am fully aware that it takes thousands of hours of training to learn to fly and do not expect to be some sort of pilot after just using a simulator. Basically the premise of the question relates to increasing chances of survivability in-case of such an emergency and there being no other experienced people on-board (even if the increase is only by a few percentage points:)

Edit: Also, if the flight crew were all incapacitated, how would one enter the cockpit?


texts: Is the A380 ailerons' kinematic modified in alternate law?

texts:
I was looking at a video of a A380 display that led me to the "valse des ailerons". This strange ailerons behaviour is available in normal law, but what happen when some fly-by-wire features are not available (alternate law and direct law)? Is this kinematic still available or do all the aileron move together acting as if there was only one aileron per wing?

EDIT: As I received no responses but multiple good comments, I add some clarifications:
The "Valse des ailerons"' purpose and operating is documented in many places (see comments) but all those documentations assume the fly-by-wire system (sensors, actuators, computers,...) is healthy enough to stay in normal law. My question is: what happen when in alternate or direct law? Is there multiple cases, some in which the valse des ailerons is still available and some in which it is not?


texts: Why Lift-induced Thrust Required(Tr) decreases and Zero-Lift Tr increases with the increase of velocity?

texts:
As the minimum Tr is at the point where L/D (lift/drag) ratio is the most. And Lift-induced Tr depends on the Coefficient of Lift, (Cl)^2 and Dynamic Pressure (q) which also increases as velocity increases. But why it is decreasing?
And how Zero-Lift Tr depends on velocity and is affected that much when its coefficient is a constant?


texts: How much energy does unretracted landing gear consume?

texts: I am interested in finding energy consumption (% kN) of unretracted landing gear  (on a jet fighter) per hour. Although the shape and size tell us how much drag is being produced I need a general rule of thumb.


texts: What are the advantages of Chemical Oxygen Generation over Gaseous Canisters on board of aircrafts?

texts:
I'm looking to get a bit of info on Chemical Oxygen generation, especially as done on aircraft. I understand the process of Chemical Oxygen Generation. I'm also aware that weight for weight it produces far more oxygen than Oxygen gas canisters.

What I want to know is are there any other advantages? Does it have added safety benefits when compared to high pressure gaseous oxygen storage? The Oxygen candle burns extremely hot when it goes off but I'd imagine high pressure gas canisters could be far more dangerous and prone to exploding if damaged?


texts: How to decide on a rate of climb or descent if no specific vertical speed is required?

texts: Obviously, obstacle clearance, charts, atc instructions etc. can require a specific rate of climb or descent, or at least pose limits that are easily calculated. When no such restrictions apply, there appears to be a large amount of freedom in selecting a vertical speed for reaching a certain instructed altitude. Are there standard rates in common use? What (preferably quantifiable) factors help pilots decide how quickly they want to get to their desired altitude?


texts: Does “trimmed for current speed” mean that the plane will do whatever to maintain the current airspeed?

texts: If I understand right, when you are trimmed for current speed, let’s say 290 KTAS, does that mean if airspeed increases to 295, the plane will pitch up to slow it back down? And vice versa for the speed falling below 290. The plane would essentially dive on it, to get the speed back? Or am I way off?


texts: Ice forms on the wings and instrument probes and vanes, but why not on the fuselage? If the temperature of the air is the same, why does the ice form on the wing but not on the fuselage?


texts: Who decides when landing gear requires an overhaul?

texts:
"If the landing gear on your aircraft is required to be overhauled periodically..."

So is there a case where its been decided that landing gear does not require to be overhauled?


texts: Which individual aircraft has carried the most passengers in its lifetime?

texts:
I'm guessing that the aircraft will be one of the 747s that service the domestic Japanese market, making regular short hops full of passengers - but perhaps actual figures exist to confirm this.

See also: Which airliners have carried the most passengers? for a related question about passengers carried by an aircraft series.


texts: What was the first fighter jet that utilised thrust vectoring nozzles?

texts: What is the first fighter jet that utilised thrust vectoring nozzles?


texts: Why do aircraft sometimes bounce while landing?

texts: I've seen a few youtube videos where an aircraft bounces once/twice while landing on the runway. Why does this happen?


texts: Can a class 1 medical certificate be obtained when glasses are needed to achieve 20/20?

texts:
Will I be able to obtain an FAA/DGCA class 1 medical certificate if I have a power of -5.75 and -6.25 in both my eyes?

It says "you should be able to maintain 20/20 vision with/without glasses" and yes, I can achieve vision with glasses.


texts: When is compressibility a problem for a pitot tube?

texts: One of the errors for a pitot tube is 'compressibility.' However, I don't understand this in detail. I get that the ASI will read slower because the ram air is compressing against the air already in the pitot tube. My question is when does this happen? What would cause this?


texts: Why do we see many more 5th and 8th freedom cargo flights than passenger flights?

texts:
Usually, we can see many cargo flights operating between 2 foreign countries (and even as domestic flights within a foreign country in some cases). There are passenger flights that operate in the same way, but they are much fewer in number.
For example, this is an image of Fedex planes flying over Asia, and none of them originate/terminate at US:

But if you take any passenger airline, then it is very unlikely that they will have so many 5th and 8th freedom flights. Why do more cargo flights than passenger flights enjoy these freedoms?
So, what's happening here? Are cargo airlines awarded 5th and 8th freedom rights more easily, or do passenger carriers simply don't apply for them, frequently, or something else?


texts: How can I use a Bluetooth headset in an ATR 72 cockpit?

texts:
Is there any device available to connect a pair of Bluetooth earphones to the audio system of an ATR 72 aircraft, to receive and transmit on the radio?

The stock headsets are horrible. I own a David Clarke headset too but the cables are a little annoying. If there's a solution to use a Bluetooth headset with a mike to replace the headset in the aircraft it would be lovely.


texts: Why don't aeroplanes automatically put out engine fires?

texts:
When an engine fire is detected the fire handle lights up and the pilot pulls it to extinguish the fire.

Why doesn't it do that automatically?
Why does the pilot have to pull the handle?


texts: This is just a question so the chat bot will always have enough rep to participate in chat -- nothing to see here.


texts: Why are the character keys on the Flight Management Computer in alphabetical order?

texts:
Regardless of which aircraft type and manufacturer, the character keys on any Flight Management Computer are always in alphabetical order, see image:

From a human factors view, this is sub-optimal, so why? Where does this order come from?

From chats with pilots I learned that you get used to it easily and can type quite fast with this alphabetical layout, but still, we are all used to the QWERTY or QWERTZ layout...


texts: What is a plausible scenario for aircraft sabotage for a science fiction novel?

texts:
I am writing a science fiction novel and my characters are about to board a private jet - they will be leaving Virginia and flying to CERN in Switzerland. Some factions are not happy with what they are attempting to accomplish and the plane is sabotaged. Here is the important part - one of my characters is an alien with limited telekinesis ability. If something is "stuck" then he will be able to save the plane by moving it, with his mind (not the plane itself - that is beyond his ability).

So my question is: What is a plausible mechanical failure that could be induced in advance by someone on the ground who was trying to prevent them from getting to CERN, that could be discovered by the pilot/crew during flight and that my alien can correct in time to save everyone using his telekinesis ability?

In the book's plot, the alien would have to be able to see it in order to move it...I know nothing about aviation so I don't know how to make this scene at least somewhat plausible -any suggestions would be deeply appreciated!


texts: When one engine fails in a twin-turbojet aircraft, is there a weight imbalance?

texts: In a turbojet aircraft with two engines, when one fails does the weight of the working engine increase due to the fuel flowing to it? If it does, how is the weight balanced on the failed engine side?


texts: How to interpret BECMG and TEMPO in TAF?

texts:
I'm still confused on the change indicator BECMG. I am sure of the definition of TEMPO being only a temporary fluctuations in the time frame given, but will a TAF with a change of BECMG continue on with the changes in the BECMG or will it revert back to the general forecast in the beginning of the TAF (basically is it permanent change or is the change only applicable in the time frame given just like TEMPO). As it says that once a TEMPO is expected to be have fluctuations of more than 1 hour it will be classified as BECMG.

This is me quoting from WMO document 306, which is also  written in Annex 3 (1.3.3):

  The change groups TTTTT YYGG/YeYeGeGe in the form of BECMG YYGG/YeYeGeGe shall indicate a change in forecast meteorological conditions expected to occur at either a regular or irregular rate at an unspecified time within the period YYGG to YeYeGeGe. The duration of the period YYGG to YeYeGeGe shall normally not exceed two hours and in any case shall not exceed four hours. The change groups shall be followed by a description of all the elements for which a change is forecast. When an element is not described in data groups which follow the change groups, the description of this element for the period between Y1Y1G1G1 and Y2Y2G2G2 shall be considered to remain valid subject to Regulation 51.1.5.

  Note: The conditions described after the groups BECMG YYGG/YeYeGeGe are those expected to
  prevail from YeYeGeGe until Y2Y2G2G2, unless a further change is expected, in which case a further
  set of change groups BECMG YYGG/YeYeGeGe or FMYYGGgg must be used.

  51.8.4 The change groups TTTTT YYGG/YeYeGeGe in the form of TEMPO YYGG/YeYeGeGe shall indicate frequent or infrequent temporary fluctuations in forecast meteorological
  conditions which are expected to last less than one hour in each instance and, in the aggregate cover, less than half of the period indicated by YYGG/YeYeGeGe.

  Notes:

  If the modified forecast condition is expected to last one hour or more, Regulation 51.8.2 or
  51.8.3 applies, i.e. the change groups BECMG YYGG/YeYeGeGe or FMYYGGgg must be used at the beginning and end of the period during which conditions are expected to depart from
  those forecast prior to YYGG or YYGGgg.
  To keep forecasts clear and unambiguous, the use of change indicators should be carefully
  considered and kept to a minimum. In particular, the overlapping of change periods should be avoided. At any time during the period of validity of the TAF, only one possible variation in the prevailing forecast conditions should normally be indicated. The subdivision of the forecast period by FMYYGGgg should be used to avoid too complex forecasts in cases where many significant changes in weather conditions are expected to occur throughout the
  forecast period.


texts: Could jet engines have a grille to prevent bird or drone entry?

texts:
A bird, or indeed any object, entering a jet engine is a very undesirable situation and may cause engine failure. There are also fears we're not far away from seeing the first incident of a drone entering a jet engine.

Why do we not see grilles or cages on the front of the jet engines to prevent this happening?


texts: What is the relation between the EASA Light Aircraft Pilot Licences and the Private/Sailplane/Balloon Pilot Licences?

texts:
The EASA licence and ratings requirements pages list:

PPL(A) - for aeroplanes
PPL(H) - for helicopters
SPL - for gliders
BPL - for balloons

which match:

LAPL(A) - for aeroplanes
LAPL(H) - for helicopters
LAPL(S) - for gliders
LAPL(B) - for balloons

It appears that you can upgrade an LAPL to its matching licence; for example, an LAPL(A) to a PPL(A) by taking further instruction and tests (except in the case of the sailplane licence, which seems not to require this, and the airship licence PPL(As), for which their exists no LAPL counterpart).

It looks like the LAPLs are generally easier to obtain (for example, requiring fewer flying hours).

What's the purpose of this apparent duplication of licensing? Are the LAPLs intended to be a pathway to the other licenses, or a destination in themselves?


texts: Does a public use aircraft need an aircraft registration hard card?

texts: Does an aircraft, operating public use, need a aircraft registration hard card?


texts: Did Southwest airlines retire flight 1380 following the accident, and with what number?

texts: Just wondering if Southwest Airlines flight 1380 was retired and replaced with a different flight number following the uncontained engine failure and depressurization accident in April 2018?


texts: Is it required to have an alternate airport if you don't have a WAAS GPS?

texts: I forgotten if an alternate is required if you don't have a WAAS GPS regardless of the 1-2-3 rule which states that 1 hour before and after ETA at your destination airport, the ceilings must be at least 2000' and 3 miles visibility. Must we file an alternate or is it dependent on the 1-2-3 rule? Which regulation talks about this because I can't find it.


texts: How could I find  lift coefficient slope?

texts:
I'm trying to find  lift coefficient slope through the below diagram, could anyone explain for me please, how could I find it?

by the way, I depend on this equation  =  (−0)


texts: Is an AFSP registration required for rotorcraft rating?

texts:
I hold an FAA private license with ASEL and AMEL class ratings and with an instrument add-on rating. [I'm trying to be precise but, basically, I've an FAA multi/IFR PPL.]

I'd like to add a Rotorcraft-Helicopter class rating to my PPL. [I.e., get rated in an R44.]

I did my fixed-wing training with AFSP approval. (I'm a permanent resident.)

Do I need to obtain AFSP approval for my helicopter training?

According to the AFSP FAQ,

  Category 3 Clarification - For flight training in the operation of aircraft with a maximum certificated takeoff weight of 12,500 lbs. or less, Candidates must obtain AFSP approval for the following three training events:

  Single Engine Land (SEL)

  -- Includes initial Airman's Certificate, including a private, recreational, or sport pilot certificate. If a private and/or commercial license is the candidate's initial FAA license, it is considered an initial airman's certificate and is not exempt.

  Instrument Rating (IR)

  Multi Engine Land (MEL)

  Each of these three events requires a separate training request.

  All other training events on aircraft with MTOW of 12,500 lbs. or less are exempt from AFSP regulations, including Commercial Pilot License (CPL), Airline Transport Pilot License (ATPL), and Certified Flight Instructor (CFI). These events are exempt only if the candidate holds an FAA stand-alone pilot certificate.

But, when asked, the AFSP said that I do need to get AFSP approval. (Citing no rule.) I've asked for clarification but does anyone know for sure?


texts: What dictates the A320's 'emergency ram air inlet' operation?

texts:
Why does the emergency ram air inlet flap open when delta p is greater than or equal to 1 psi on the A320?

Below is the extract I was reading from the FCOM. Why has the figure of 1 psi been set for opening or closing the flap?

  The emergency ram air inlet opens
  ‐ If Δp ≥ 1 PSI: The outflow valve control remains normal. No emergency ram air flows in
  ‐ If Δp < 1 PSI: The outflow valve opens to about 50 % when under automatic control. It does not automatically open when it is under manual control. Emergency ram airflow is directly supplied to the mixer unit.


texts: How does ATC handle tv coverage of police pursuits in the US?

texts:
On YouTube there's a lot of aerial footage of US police pursuits to be found, usually filmed from news helicopters, flying around and doing a lot of maneuvering in the same small area, sometimes in the immediate vicinity of big airports.

Almost always there are more helicopters involved: Police and tv stations, you can sometimes see them crossing the camera view. And all of this time, essentially no one knows where things are going. The whole thing seems to me quite hazardous from an aviation point of view, maybe even more so than the proceedings on the ground.

How are these operations kept safe? Under what rules or procedures does ATC handle this kind of situations?


texts: Can pilots change the callsign shown on tracking websites mid-flight?

texts:
Today I viewed the following flight on FlightRadar24 website. It show a flight with a callsign of 'BLEED' and with the destination missing. Is this a problem with the website or can an aircraft change its transponder data to show such a callsign?

And this is a news report item about this flight:

https://www.jpost.com/Breaking-News/Flight-enters-Israel-from-Turkey-with-call-sign-BLEED-573889


texts: Will I fail a check-ride if I do a go-around for a short-field landing?

texts:
Let's assume that I'm on a check-ride and my next requirement is to perform a short-field landing.

If I'm coming in for landing and it's obvious I'm not going to hit my mark, can I perform a go-around and try again? Would that be considered a fail?


texts: What are these protruding things on this Russian military aircraft (MiG-31BM)?

texts:
See the video

In the video it is clear that the jet takes off and lands with all these 3 things "open/stretching out" (so it seems to fly just like that - not retracting them).

Here is Wiki on that model.


texts: What is the correct procedure for operating the engine fire extinguishers on an ATR72?

texts:
I am developing an application for airport fire crew and ground staff. Part of the application is to familiarize users with emergency procedures of various aircraft. I have a few questions about the procedure for discharging the engine fire extinguishers on an ATR72 that I hope someone can help me with:

As I understand it, pilot must pull the red handle and twist 90 degrees. This will stop the engine. Pilot must then press the discharge squib button in order to deploy the extinguishers. is this correct?
What would happen if the pilot pressed the discharge squib button before pulling the red handle?
Am I correct in assuming that if the system has detected an engine fire, then the "fault off" buttons would be lit and there would be an audible alarm? If this is the case, would the alarm stop when the discharge squib button is pressed, or only when the fault off button is pressed?
Above the buttons it is written: "Agent 1 Loop A" and "Loop B Agent 2". what does this mean and what is the difference between the two systems? In what circumstances would the pilot have to press both discharge squib buttons or both fault off buttons? In what circumstances would they only have to press one?


texts: What would the pros and cons be of this 'zig-zagged' high-sweep wing planform?

texts:
What would be the advantages / disadvantages of the following wing planform for supersonic aircraft?

The suggested planform is in red; a more conventional, delta planform is illustrated for comparison in white. I was wondering if a zig-zagging leading edge would increase efficiency at high speed due to the increased leading edge sweep without a decreased aspect ratio. I was also wondering if improved control at high angles of attack would be an added bonus, like the "dogtooth" on the F-4 Phantom. I suspect that reduced structural strength could be a disadvantage.


texts: Where do the compressed gasses of a charged engine goes?

texts:
Good day to you here.
I'm working on a modified version of 2-stroke engine. My plan is to use a supercharger for the scavenging process, instead of the conventional Crank case scavenging technique, thereby excluding the Crank case from the entire scavenging process.

But I have a question that's bothering me, In a charged (super or turbo) four stroke engine, after the the inlet port has been closed by the inlet valve, where does the subsequently compressed gasses go? Do they find their way back through the air filter? Do they remain in the inlet manifold until the inlet port opens again? Does this part of the engine cycle has any negative effect on the overall performance of the engine?

Note: Do excuse my grammatical blunders.


texts: What is the busiest airport in the world, and how is this measured?


texts: Can I spot the drones watching me in the sky with naked eyes?

texts:
To quote John Oliver:

"Yemen, home to 26 million Yemeni people, and 27 million American drones."

While these numbers may be slightly exaggerated I started to wonder. As far as I know, military drones are used primarily for survaillance, meaning that they circle a potential target for hours on end to gather intelligence.

I immediately thought, that they would be spotted quickly, and any illegal activity would cease. Since they seem to be effective though, this can't really be true.

So my question is: Given typical operational parameters during survaillance, can military drones, like the Predator, be spotted with the naked eye if they are circling above you?

I tried to find an answer with some quick calculations of my own.

I can see quite a lot of airliners flying above me, and I can see their bodies quite easily. Airliners are larger though.

Some sizes I could gather are:

A320 Source

Length: 37.57m
Wingspan: 34.1m
Body width: 3.96m

Predator Drone Source

Length: 8.23m
Wingspan: 14.84m
Body width: 0.83m (estimated from picture)

When I look at just the length of the aircraft, I can calculate the angular size of the object in the sky if I know the altitude. I assume the A320 flies at around 32000 feet, or 9753m. For the drone I have no idea. But it can fly at 7620m and I would assume it stays a bit below, so I assume 6000m.

The angle of the object is then:

Angle = ArcTan(Length/Altitude)

The human eye has a resolution of 0.5-1 arc minutes, or 0.0125°.

For the given aircraft I come to these values:

A320:
Angle = Atan(37.57/9753) = 0.22°

Predator:
Angle = Atan(8.23/6000) = 0.08°

So from the length, both aircraft should be visible. However, that doesn't seem to make sense, because they need to be wide enough as well. So for the body width's I get:

A320:
Angle = Atan(3.96/9753) = 0.024°

Predator:
Angle = Atan(0.83/6000) = 0.008°

So the A320 should be visible quite comfortably, while the drone should be invisible to the naked eye.

But

This is all theoretical. I don't know the operation of the predator, especially how high it flies. I also don't know what really determines visibility. Does the wingspan alter the numbers?

Can anyone share any actual insight?


texts: How do pilots use stopway, EMAS, clearway and displaced threshold?

texts:
I noticed in Why is “clearway minus stopway” used in V1 adjustments? that a stopway and an EMAS are both indicated by yellow chevrons:

Same Opa-Locka stopway on the left, and San Diego EMAS on the right. Source: Google Maps

I believe the EMAS could somehow damage the aircraft (e.g. the nose gear). This would be acceptable as this is a last resort choice to prevent exiting the runway in an overrun, and likely more serious consequences.

EMAS in use. Source: flysfo.com

In the other question it is mentioned that a stopway mustn't damage the aircraft. So my first question was What is the difference from a regulation point of view? And how the pilot can know if this is a stopway were braking is desired, or an EMAS where thrust reversers might be hazardous.

However I thing it could be interesting to open the scope and get a more complete view, so my questions are more:

How do pilots use non regular runway portions such as clearway, stopway, EMAS, displaced threshold, and possibly more of this kind if it exists?
Is there some regulation which limits them for taking off, taxiing, or landing?


texts: Why don't airlines install Faraday cages in their planes?

texts:
Cell phones and other electronic devices can interfere with the pilot's comms and other crucial avionics, as well as cell towers on the ground, if the plane is low enough. Due to these issues, the FCC forbids using cell phones on planes, while the FAA allows airlines to choose when they may be used, once the plane is out of range of the ground cell towers.Source

The fact is, though, many people just don't put their phones on airplane mode. You can forbid it all you want, but without enforcing it (not feasible - too many ways to get around it), it doesn't do much.

Enter the Faraday cage.

Faraday shields are, in short, metallic surfaces that prevent the transfer of electromagnetic waves from one side to the other; Faraday cages are ones with holes in them, blocking waves of specific wavelengths while allowing all others through. You've surely seen Faraday cages before; they're in the doors of all microwaves.

This seems to be an easy (perhaps somewhat expensive) solution. Just put one up on every airplane, maybe with a wire going from one side to the other to allow the on-board Wi-Fi to still work. But it would block all outside communication, regardless of if you've got airplane mode turned on or not. If the cage is routed around/inside the sides of the planes and across the door between the cockpit and the cabin, the pilot would have no problem communicating with the outside world.

I feel like I'm overlooking something obvious, but I can't put my finger on it. Is there a hole (so to speak) in this theory?


texts: During an engine failure should I deploy 10° of flap or keep it clean?

texts:
Imagine I have an engine failure in cruise flight with a Cessna 152 or 172.

Should I select 10° flap to increase glide angle?
Would it give me more range to reach safety?


texts: When are you allowed to use a call sign that is not the aircraft registration?

texts:
Some General Aviation pilots use their aircraft registration as a call sign, like C-ADYDJ for example. I've heard some use their aircraft type then some numbers like Cessna 45G. Then the typical airliners who use their company name then flight number, like ACA783.

When are you required to use your aircraft registration, and when are you allowed to replace it? If you are allowed to change it, can anyone use whatever call sign they want or is it limited to airlines only?


texts:
In the US, is there a way for a pilot to legally "maneuver at will" in actual IMC?   Let's say you want to practice a series of reversing 360-degree turns and not have to communicate every change in heading to a controller or follow a controller's step-by-step instructions.

For example, is there such a thing as an IMC "practice area" where only one aircraft at a time is allowed to operate under IFR?

Also, is there a distinction between controlled and uncontrolled airspace in this regard?


texts: Do codeshare & alliances conflict with competition?

texts:
I am aware of the advantages that codesharing has on airlines such as
- allowing airline to expand operations without physically flying to that destination

creating perception of large flight network
reduced operation costs from seat transfers e.g KLM & Kenya Airways on the NBO-AMS route

However my concern is ;

are there any other further benefits ?
do codeshares reduce competition?
can codesharing airlines compete ? (e.g Star Alliance members, Lufthansa & Thai Airways)
do alliances reduce competition ?
can airlines of the same alliance compete ? (e.g Oneworld members, British Airways & American Airlines)


texts: What drives N1 during a jet engine start?

texts:
A typical jet engine start sequence that I understand is as follows:

ENG Start Switch to Ground → Start Valve open → N2 increases → N1 increases → ENG Start lever to Idle (when N2 has reached a certain number) → Fuel flow starts → EGT rises → ENG Start Switch cutout

As far as I understand, N1 and N2 are mechanically seprated. If that's the case, what drives N1 before it starts to rotate from the following combustion?


texts: Where can I listen to the actual cockpit voice recorder audio from US Airways Flight 1549?

texts:
I have searched for the audio recorded on the CVR from the US Airways Flight 1549, but all clips and audios I found seems to be audio recorded from the flight control and not from microphones inside the cockpit.

For example:

In this clip, we only hear the pilot sparsely, but the air traffic control and the airport tower controls quite often. Although, we can also see a transcript of what is said in the cockpit, so there obviously exists some recordings from the cockpit.

Where can I listen to the audio recorded from the cockpit and not from the air traffic control?


texts: How can a Cessna cut the wing of a Boeing?

texts:
I read days before about the collision of the flight PSA Flight 182 on September 25, 1978. I was wondering how is it possible that a Cessna 172 can CUT Boeing's 727-214 wing. There is a video with the moment: video.

Is there an explanation of how this can happen scientifically?


texts: Why do some aircraft (e.g. Avro RJ85) have rear-mounted air brakes?

texts:
I recently saw an Avro RJ100 on approach and I wondered why the Avro RJ100 and also the RJ85 have the air brakes at the rear of the aircraft, and not on top of the wings like most airliners?

(photobucket.com)

What is the advantage you get from this, and/or what made it impossible to mount the air brakes on top of the main wings?


texts: What should I expect during a first class medical examination?

texts:
About 57 months ago I got my first FAA medical, a second class certificate.  I am currently a sophomore in college.  I'm in AFROTC trying to become an Air Force pilot so I wanted to get a first class medical just to make sure that I can (I realize military aviation medicals are even more intense though).

What types of things do they do during an exam for a first class medical that aren't included in the exam for a second class?  Also, if I "fail" one of the tests while being examined for a first class - can I still get a second or third class medical to keep my private pilot privileges?


texts: Is the ratio of HP to weight constant for identical air frames of different sizes? (See Scenario)

texts:
In my head it seems logical that there would be a proportion between engine HP and empty weight. For example, the Wright Flyer weighed around 600 LBS empty and had a 12 HP engine. If I were to make an exact 1/6 size scale replica out of the same materials that weighed 100 pounds and had a 2 HP engine, would that aircraft fly as well? Would the performance be exactly the same? Thanks in advance!!!

(Don't bother accounting for the pilot's weight.)


texts: Why are there out-of-date tower frequencies on the VFR sectional chart, without a NOTAM?

texts:
I flew today to Salinas, CA and had a little trouble reaching Salinas tower (KSNS). The current VFR sectional shows the tower frequency as 119.4. However, apparently the frequency changed to 119.525 on June 2014 (according to http://www.montereybay99s.org/newsletter/July2014issue.pdf)

The current VFR sectional was issued in August 2014, after the frequency change. I'm wondering why (a) the frequency is incorrectly printed on the current VFR sectional, and (b) if it's an error why there is no NOTAM about it.


texts: Why do English-speaking pilots and ATC say "Niner" instead of "Nine"?

texts:
Besides the fact that it's now a standard, why do American-English-speaking pilots and ATC say "Niner" instead of "Nine"?  None of the other numerals are pronounced in an atypical fashion.

For what was "Nine" being mistaken that resulted in the "Niner" standard being adopted?


texts: Does the European Aviation Safety Agency (EASA) provide real-time data feeds and is there a delay?

texts:
According to this answer:

  You can't get real-time data from the FAA without an operational need, and organizations which do receive real-time data cannot legally re-distribute this data publicly, except to other organizations approved by the FAA. An operational need pretty much means you have to be a flight dispatcher for an airline or commercial operator, not just have an interest in tracking flights.

Great, now apparently, the data feed is delayed by at least 5 minutes... according to this answer.

Does the EASA provide data such as that provided by the American
FAA?
If so, is there also a delay on data?

If so, what is the delay?

Thanks!


texts: What is this INOP instrument and when is it safe to fly with INOP instruments?

texts: I flew ZRH->LHR on BA0711 today on G-EUOG. I noticed through the cabin door one of the instruments had a yellow INOP sticker across it (see photo). Which instrument was it? I am presuming the instrument has a backup, and the backup was operative, but I had thought the purpose of an backup was so that it could be used if the primary failed in flight? Or is the instrument just 'not important'? What are the rules re flying with INOP instruments?


texts: How do modern helicopters tackle Vortex Ring State?

texts:
According to the wikipedia page :

  Air vortices can form around the main rotor of a helicopter, causing a dangerous condition known as vortex ring state (VRS) or "settling with power". In this condition, air that moves down through the rotor turns outward, then up, inward, and then down through the rotor again. This re-circulation of flow can negate much of the lifting force and cause a catastrophic loss of altitude. Applying more power (increasing collective pitch) serves to further accelerate the down wash through which the main-rotor is descending, exacerbating the condition.

The vortex ring state has also been listed as a potential hazard in the Wikipedia page for helicopters. What are the various preventive measures used to prevent such a condition?


texts: What direction should a traffic pattern be at an uncontrolled or non-towered airport?

texts: What is the standard direction for a traffic pattern at an uncontrolled or non-towered airport?


texts:
Is it possible to have a fully electric airliner?

How much room would have to be sacrificed for a power bank in these aircraft to allow similar range to the current models (e.g., A320, 737, etc.)?

Would it shrink the passenger capacity by a lot? Or is the concern mainly having enough power to push such weight?


texts: Why are there so few carrier capable delta wing aircraft?

texts:
When looking through various carrier aircraft, I noticed that there seemed to be very few with delta wings. While initially chalking this up to higher stall speeds necessitating higher approach speeds on supersonic deltas, I nevertheless noticed that this seemingly doesn't apply to the Dassault Rafale, nor the HAL Tejas.

Is this due to configuration? Would the addition of canards or conversion to a tailed delta permit carrier operations? Or is this not aerodynamic but more based off cost?


texts: Which trigonometric algorithm does an FMS use to determine distance between waypoints?

texts:
When entering waypoints into an FMS, the FMS calculates bearing and distance between them.

Does it use "normal" spherical trigonometry equations, or go for the more accurate Vincenty algorithm which takes the earth to be an oblate spheroid?


texts: Why are some airplane wings not painted?

texts: Why is it that some wings are not painted on commercial jets? Couldn't they paint them the same color as the fuselage or would it be a waste of money?


texts: Can a tail pipe fire occur in cruise? If not, why not?

texts:
I was reading the news for an incident where an A321 had to divert due to:

  the aircraft returned suspecting a tail pipe fire on the #1 engine, the crew did not receive any engine fire indication or other abnormal parameters, however, as a precaution discharged the fire extinguisher into the engine after it was shut down. There had been an engine tail pipe fire.

However, according to SKYbrary,

  A tailpipe fire will only occur on the ground and only during engine start or during engine shutdown.

Finding the latter source more reliable, I assume that either the report was wrong or the flight crew did not know that tail pipe fire is not possible in cruise.

My questions are:

Is a tail pipe fire really only possible on the ground?
Why is that? Are there not any situations (possibly abnormal, such as a flameout and attempted reignition) that could cause a tail pipe fire to occur in cruise?


texts: Is it possible to make an analogy between a lever and an airplane wing in terms of force applied over distance?

texts:
On most aircraft the engine force (thrust) is lower than the weight. Since wings therefore are always capable of generating greater force (lift) than the engine, there is an analogy between an airplane and a lever.

Now, a lever produces greater force by doing the same work on a shorter path. How can we prove that wings enable the doing of work on a shorter path than the engine thrust? Is it reasonable to say the path on which the thrust does the work is the distance the aircraft needs to accelerate to takeoff speed, and the work/energy accumulated this way is used by the wings to exert greater force on a shorter path on the air? (And then this kinetic energy is constantly replenished by the engine keeping it constant, assuming no further acceleration?)

Is this the right Newtonian explanation of flight? How can I find the distance on which the force is doing work on the air?


texts: How to record Intercom / ATC in a small aircraft like a Piper Archer?

texts:
For making videos it would be nice to have some more sound than the engine sound recorded by my GoPro. What ideas do you have to record the aircraft intercom? It won't be a problem for me to have two files (an audio and a video file).

Edit: I'm looking for a good sound quality comparable with that which you will have while sitting in the aircraft listening to the intercom.


texts: Why are wind tunnel models sometimes placed upside down?

texts:
Sometimes in wind tunnel tests, models are suspended upside-down:

Image obtained from DNW - Interference corrections

Image obtained from this Youtube video of testing at AEDC

Image obtained from UWAL - Model Support Effects

And sometimes they are in the normal flying position:

Image obtained from TRI models - wind tunnel testing

What is the specific reason for putting wind tunnel models upside-down?

I thought it had something to do with minimizing the influence of the support, but putting the plane upside down doesn't change much about the location of the support.


texts: How are takeoff and stall different from each other?

texts:
Technically what differences are there between a take off and a stall?

From what I understand, when stalling the aircraft will lose lift when a certain angle is met. On a takeoff the aircraft will pitch the nose up but the effects are different.

What affects this? Is it the effect of the relative airflow or something else?


texts: Why do most radial engines use an odd number of cylinders?

texts: To help suppress vibration, most 'V' and 'horizontal' engines use an even number of cylinders as closely opposed as possible. Radial engines are well known for excessive vibration. For some reason they nearly always use a staggered odd number of cylinders that would seem to promote vibration, why?


texts: Are the press reports of this incident plausible?

texts:
On May 21st, before an Air Berlin flight from Düsseldorf to Stuttgart (~340 km, 210 mi), a hole in the fuselage of the plane was discovered by passengers. It is claimed, that the crew continued flight preparations, dismissing warnings and only abandoned the take-off after the pilot was pressured by passengers to take another look. He is said to have deemed the plane suitable for flying and only abandoned the idea when pressured by passengers to check the plane again.

Air Berlin claims, that the pilot interrupted his preflight walk-around check of the plane, to return to the cockpit for some tasks. He later continued it and spotted the hole, leading to the cancellation of the flight. Meaning: Everything would have been fine without any passenger warnings anyways.

English sources:
https://theworldofaviationblog.wordpress.com/2017/05/23/passengers-discover-hole-in-the-side-of-air-mistral-atr-72/
http://true-news.info/passengers-air-berlin-found-a-hole-in-the-fuselage-of-the-aircraft/  (has to be true obviously)
German Sources:
https://www.merkur.de/welt/passagiere-entdecken-vor-air-berlin-flug-loch-im-flugzeug-zr-8347888.html
Aviation Safety Report:
https://aviation-safety.net/wikibase/wiki.php?id=195623

For me this whole story seems fishy: I find it unlikely that the pilot and ground crew would have missed this damage. I also find it very unlikely, that the pilot would ignore a serious threat to the safety of the flight. It's his life on the line as well.

So now I have a few questions about it:

Does the airline's explanation make sense? Does a pilot start his outside checks but sometimes interrupt them to take care of business in the cockpit and then continue later?
Would the hole have been a problem in the first place? Was it maybe, from a technical standpoint, really not a problem and the crew later only bowed to the (uninformed) pressure of the passengers? Flight attendants apparently told the passengers to "get in and trust us".
Is such a hole fixable by that hardcore-airplane duct tape, and are such fixes done shortly before take-off?


texts: Was my latest Air Berlin flight in violation of some in-flight procedures?

texts:
I was quite surprised about one (all?) of doors on my latest Air Berlin flight. In particular:

the "Door locking indicator" was empty (black),
the "Cabin pressurized" light was not lighten and
the "Remove before flight" red strip was not removed.

(I am the owner of this picture and I authorize anyone to use it for any purpose except illegal activity.)

The plane landed safely and there was no noticeable in-flight change of air flow/pressure etc. Still, I wonder if the described situation is a violation of some in-flight procedures or at least odd in any way?


texts: Who do I call to pick up my IFR Clearance at KBKL?

texts:
I've had my IFR rating for ~2 years now, but haven't done much other than practice approaches to stay current. Flying to KBKL tomorrow, and when I depart to come back, I can't tell who I call to pick up my clearance.

The approach plates say "CLNC DEL 121.9 (when tower closed)" - okay, what about when the tower is open?

I've tried googling around, but the internet is filled with people asking how to pick up clearances in the air; I trained at a non-towered field so I've got the opposite issue.

Thanks!

Edit: Here's a link: http://airnav.com/airport/KBKL


texts: Is "Tally-Ho" used in ATC radio communication, specifically in the UK?

texts:
This question Are "Tally-ho" and "no joy" acceptable ATC terms for civil operations? concerns the use of the phrase "Tally Ho" to mean "target in sight" in civilian air-traffic-control communication.

It was largely answered (and somewhat asked) in relation to the US/FAA, where it is not acceptable but sometime heard. However "Tally Ho" is/was a British phrase, and my question asks the same specifically of British/NATS/CAA communication. Again, I'm interested as to whether it is actually heard, and whether or not it's generally considered acceptable.

I am aware that some efforts are made to keep English usage international, though most feeds/transcript I've heard from the US have an awful lot of regional idioms and phrasing in them, so I'm not sure the extent to which it is adhered to.

(For people outside the UK, "Tally Ho" is generally considered archaic and comically mannered in general life these days, even within the UK, which is why I'm particularly interested as to whether its usage survives here in aviation).


texts: Does maximum altitude increase when pilot is acclimatised?

texts:
Normally 10,000 ft is considered safe altitude for emergency descents and 12,000 ft a maximum that can be flown in unpressurised aircraft without using supplementary oxygen.

But when flying in the mountains with a crew that normally lives at say 5,000 ft or more, can they afford higher altitude? And by how much?

Note: The 12,000 ft I've seen somewhere, but I don't know whether it is actually a regulation or just recommendation.


texts: What is the minimum set of registers to fill for ADS-B?

texts:
I am researching about Automatic Dependent Surveillance-Broadcast mode of Mode S currently. On a third party document, I encountered a list of transponder registers to be filled; 05, 06, 07, 08, 09, 0A, 61, 62, 63, 64, 65 as the list of registers.The source is Grappel 2007- ATC 334.

05(Airborne position), 06(Surface Position), 08(Aircraft Id), 09(Airborne velocity) registers seem to be carrying most important data for ADS-B.

Registers from 61 to 65  are called event driven registers, carrying slowly changing data. SHALL these registers have to be filled with correct values to serve ADS-B IN capable systems? What happens if I don' t service these event-driven registers?

Is there a definitive list of registers to fill current settled ADS-B standards?

Note: I have access to many documents, so feel free to refer some well-known ADS-B documents.


texts: What permissions or approval are needed to land in Antarctica?

texts:
Can I land at Jack F. Paulus Skiway (NZSP) with just an ATC clearance? Or do I need to ask some other authority before I fly there? Are there any regulations regarding 'landing rights' in Antarctica?

Edit:

Let's assume I am in a private aircraft that is able to safely fly to NZSP where I am flying under IFR. Do I still need permission from some kind of authority? And what about commercial flying?


texts: Why does the Cessna 208 Amphibian have extra tail surfaces?

texts:
Mark Harkin, CC BY 2.0, via Wikimedia Commons

I've seen extra tail surfaces that look like additional vertical stabilizers on the C208 Amphibian. Why is there a need for this? I can't imagine that the floats reduce vertical stab effectiveness.


texts: Is B 737 Max able to comply with certification if MCAS is off or removed?

texts: Boeing 737 Max updated MCAS will probably be cutted off in case of AoA disagree. Without MCAS, the plane is no longer similar to 737 NG (stick force per g requirement). Does that mean a new certification ?


texts: What are these things on strings after the loss of cabin pressure?

texts: I saw a picture on Twitter after the loss of cabin pressure. I've seen these images many times before, but in this picture, there are some things on strings that I cannot identify.


texts: Why is Schaumberg Airport (06C) in Chicago an uncontrolled field?

texts: Schaumburg Airport lies underneath some of the busiest airspace in the world and is 8 miles west of Chicago O'Hare, one of the most active airports in the US. It's not the busiest uncontrolled field in the US, but it gets more traffic than some towered airports. Given the location, airspace complexity, and airport popularity why is Schaumburg an uncontrolled field?


texts: How can compartment bay loading informating be derived from the IATA load message (LDM)?

texts:
In the IATA Airport Handling Manual procedures, messages are send to communicate with the transit station to describe the cargo load. The Load message LDM (AHM 583) is sent primarily to enable the transit station to know in advance the load which continues on the same aircraft.

  LDM ZZ999/13.ZZOEA.Y136.2/4
  -SHJ.15/22/3/1.T1500.3/1000.4/500.PAX/40.PAD/0
  -CMB.27/22/12/3.T3500.1/2800.5/700.PAX/61.PAD/0 SI

In here we got  hold id 3 total gross weight 1000kg,...
In our automated system, we need info in compartment bay level.

How can we get those information?

Any other message like Container / Pallet Distribution Message CPM (AHM 587)?
Or we have to manage manually (should distribute by load controller)


texts:
With all the issues surrounding the Ethiopia crash can you tell me what a 73W is?  Is it a 737 Max 8.  We're trying to figure out if our flights with Westjet on Friday might be effected.

Thanks

Frank N


texts: What is the correct name for this ILS Indicator?

texts: What is the correct terminology for the name of the aircraft instrument that looks like this?


texts: How can I isolate altitude as a specific range variable on a Sporty's electronic e6b?

texts:
So, I'm trying to understand the specific range calculation on my Sporty's E6B electronic calculator. The manual gives two examples.

In one, the assumption is 150 Ground Speed, 24 Gallons of fuel per hour and 140 gallons of fuel on board. It also assumes 12000 MSL. The answer is 875 miles.

Then there is another example: 160 GS, 27 G/Hr, 140 gallons on board, and MSL is 8000. The range changes to 855.6.

The problem is: the altitude is not an enterable variable (those others are). Entering it and adjusting in different parts of the calculator does nothing. Does anyone know how to isolate MSL as variable in this device?


texts: Is altitude and heading your discretion when you are cleared visual approach?

texts:
If I'm north of KSAN heading east and the controller clears me for the visual approach for runway 27, can I descend and turn the plane at my discretion so that I  can get ready for landing?

Also, once a controller clears me for the visual approach and I accept it, am I responsible for my own terrain and obstruction clearance?


texts: What is the risk of leaving the MAN START PB 'ON' on the A320?

texts: During a manual start on a A320, the ENG MAN START P/B opens the start valve which then runs the starter motor. During the MAN START process, at some point, the start valve closes automatically. What are the risks associated with continuing to leave the MAN START P/B ON at this point?


texts: Can light GA aircraft implement fly-by-wire technology?

texts:
Theoretically, I know it is possible. I know the benefits of fly-by-wire too.

My question(s) most revolve around:

why it hasn't been done?
What challenges1 would there be?
What benefits are there by not implementing it even for new light GA aircraft2 being produced?
I know that many smaller airplanes (e.g. Cessna 172) do have fly-by-wire flaps. Why the remaining flight controls don't use this technology?

1: Not considering money as an issue.
2: I couldn't find any reference of it for Cessna Skyhawk.


texts: Does the term track guidance apply only to conventional procedures?

texts:
In ICAO's 8160 "Aircraft Operations" manual there is a term called "track guidance", for which I can not find any clear definition.

A few examples:

  Departure Procedures 3.1

  3.1.1 There are two basic types of departure route: straight and turning.

  3.1.2 Track guidance shall be provided:

  a) withing 20.0 km (10.8 NM) from the departure end of the runway (DER) for straight departures; and

  b) within 10.0 km (5.4 NM) after completion of turns for turning departures.

  3.1.3 Surveillance radar may be used to provide track guidance.

..

  3.2.2 Types of Straight departure

  b) straight departure with track guidance:

  1) facility ahead or behind; and

  2) offset (track parallel/track offset/track crossing).

..

  1.6 TRACK GUIDANCE

  1.6.1 Track guidance should normally be provided for all phases of flight through the arrival, initial, intermediate,
  final and missed approach segments. When track guidance is provided, the appropriate segment shall lie within the
  established coverage of the navigation facility on which the track guidance is based.

Judging from the context in which track guidance is mentioned, I would say that it refers to conventional navaid-based procedures, where the aircraft needs navaid facilities in order to keep on track.

All things considered, does the term track guidance have any meaning for RNAV/RNP procedures? Are RNAV/RNP procedures considered procedures without track guidance?

Any clarification would be appreciated.


texts: Why developing F-35 is harder than F-22?

texts:
I'm sorry if I'll be not so accurate in my description but, please, try to understand "core" of my question.

F-22, ignoring high cost of each aircraft, appear to be a successful project, developed and delivered in almost desired timeranges respecting requirements.

I sincerely don't understand why F-35, that initially was thought to have almost same stealth performances of F-22 but at an individual cheaper cost, is running into troubles, difficulties, risk of abandoment since years.

Develop is still ongoing and reliability and performances are still not satisfied. I thought that experience based on first stealth high perfromance fighter jet could help and speed up an aircraft like f-35 that should have lighter requirements but facts are demonstrating the opposite


texts: Why is there a helicopter visibility reduction restriction for this approach?

texts:
For the RNAV (GPS) RWY 17 approach at KSMN, why does it say "Helicopter visibility reduction below 3/4 SM NA."?

Looking at the LNAV, there is a 5 mile visibility requirement and if we cut that in half per AIM 10-1-2, wouldn't there be a 2 1/2 mile visibility requirement? If so, then a helicopter couldn't fly the approach with 3/4 mile visibility anyway.


texts: Would a piston or turbine engine be best suited for a small UAV flying 8000miles?

texts:
I am trying to devise a concept that would airdrop medical supplies around remote regions of Africa: vaccines, medicine, blood... etc. I image the payload would be anywhere between 1-2 ton. I think a UAV would make the most sense because then you don't need to worry about flight-time, speed, pressurization, bathrooms and pilot logistics.

Range is an issue because I might need to determine where to set up runways. Africa spans thousands of miles. Ideally, 8000 miles would be great because you can take off from Europe or Egypt or Israel , then fly anywhere in Africa and return without landing to refuel. But landing at a hub to refuel would double the distance -or half the required range.

Payload weight is something I think about a lot and I need to do more research. Like, how light can you make vaccines? There would also be the syringes and other medical supplies. Also, because of the cold-storage cooling and parachutes I think 1-2 ton is a good estimate.

I was looking at electric powered options and these aircraft are typically short range and expensive. Unless you look at the Impulse 2 which has infinite range, but was $128 million to develop.

So in short, long range, light-ish payload, speed doesn't matter and as cheap as possible.


texts:
I am referring to an Airbus A320. I have heard of Pack Flow but I don't understand it.

If you put it on High, does that mean that all the parts of the air conditioning system work faster and harder?

I have also heard that if you put it on High, that means the demand for air supply is high, and vice versa, i.e. if it's on low then the supply for air is low, but what about NORM, or Economy flow?


texts: Could a supersonic fighter upset or damage a 757 by close flight?

texts:
In another thread, we are discussing the events of 9/11/2001, and what options an F-16 pilot would have, if it became sadly necessary to force a 757 to crash. It is presumed the F-16 does not have normal armaments; no cannon nor missiles.
How could the F-16 cause critical problems for the 757 simply by flying quite near it, including supersonic?
Spitballing some examples of what might be answers: using supersonic turbulence to cause one wing to stall; crossing the engine's airstream and causing a flame-out somehow; a supersonic near-pass physically damaging the airframe.
And we should presume we have a very low-hour Cessna student pilot, not an experienced commercial pilot who trains for problems.  An upset that a competent pilot could recover from is fatal if the student pilot has no idea how to recover from it, or would tend to do the wrong thing.


texts: I am a student in Tanzania and it's required to take PGM (physics, geography and math) to qualify for studying as a pilot. After qualifying, what am I supposed to do to study for a CPL, and what help can I get if my financial status is limited? Are there any scholarships for people in this situation?


texts: Why does a pilot bank up to 5 degrees into the operating engine following failure of the other engine?

texts: If a multi-engine aircraft suffers an engine failure while near minimum control speed (Vmc), one of the solutions is to bank up to 5 degrees into the operating engine to increase rudder effectiveness to maintain control. Why is it up to 5 degrees? What happens if the pilot banks more than 5 degrees into the operating engine?


texts: Do airplanes with fixed gear usually turn upside down during water landing?

texts:
During discussion about emergency landing on water in this YouTube video (4:00) the flight instructor said:

  "...the problem with these airplanes with a fixed gear, you're usually
  going to be upside down".

Is it really like this? If so, is there any water landing technique which could minimize the risk?


texts: Has a flight data recorder or cockpit voice recorder ever failed in an accident?

texts: Has there been a time either during an aviation accident or during normal flight where the flight data recorder or the cockpit voice recorder devices failed or the data was significantly corrupted?


texts: How exactly are checklists shared between the pilots?

texts:
Plane startups are shared between the crew

But how exactly? Does the captain do the startup and then ask the copilot if everything is correct? How exactly does it work? Is it aircraft specific or airline specific?


texts: Is takeoff permitted from an aerodrome inside a CTR when it's outside the tower's operating hours?

texts:
I am departing from an airfield which is within the CTR of a nearby airport but outside tower operating hours. The chart doesn't specify this situation.
According to ICAO rules,
Am I allowed to take off or not?
EDIT: this is not an EASA or FAA specific question. Rather international, ICAO rules, but if there are different conventions it's also good to know.


texts: What is that wire connecting the tail fin to the fuselage in beechcraft 1900 and so many other airplanes


texts: How is stability ensured with bulk-loaded cargo?

texts: According to this question especially smaller airlines often don't use ULD in the cargo hold. But wouldn't that be dangerous for the stability of the aircraft? Won't the cargo move and unbalance the aircraft?


texts: Do aircraft obtain better milage by flying high or by using "ground effect?"

texts:
It has been said the most fuel efficient way to fly is by flying in thinner air. On the other hand the largest plane in the world was the Russian "Caspian Sea Monster" Ekranoplan, which is said to be the most efficient plane for its weight.

Which method of flying is the most efficient and by how much when it come to time and fuel?


texts: Can anybody explain to me what suction peak is and does it have anything to do with lift and drag? I've read that suction peak is the point where the coefficient of pressure is the least and is located just behind the leading edge - is this statement true?


texts: How do military radars detect the type of an aircraft?

texts: How do the military air defense radars and aircraft radars detect the type of an aircraft and enemy or friendly information?


texts: What is the maximum amount of noise an aircraft is allowed to generate?

texts: Has the FAA regulated yet the maximum dBs of noise an aircraft's engine is allowed to generate, and what the range of "safe operation" would be? If they have, what are their regulations on it?


texts: What factors influence the maximum speed of an airship?

texts:
I'm interested in learning about the physics of airships; in particular, how you determine an airships maximum speed.

For example, the Hindenburg topped out at about 80 mph. The ship itself weighed about 130 tons, not including cargo, passengers, etc.

If it weighed less could it have achieved a higher top speed, or would 80 mph have been about the fast it could have gone regardless, for other reasons such as drag/air resistance?

If it had twice as many engines, could it have gone twice as fast?

These are oddly specific, noodly questions, and I'm not looking for the answers themselves, but rather I'd like to be pointed in the direction of the math/physics fundamentals for getting the answers. I'm working on designing some fantasy airships for an RPG, and of course while they're not real and very fantastical, I do want them to have some semblance of verisimilitude, and imposing real world physics (with some wiggle-room for the fantasy part) I think helps a lot.

Thanks so much for your time and answers!


texts: What differences are introduced between ICAO Annex 10 volume IV amendment 85 and amendment 89?

texts:
What changes have been made to ICAO Annex 10 volume IV (Surveillance Radar and Collision Avoidance Systems) between amendment 85 and amendment 89?

I only have access to amendment 89, but I have some material referring to amendment 85. What is the difference between these versions, what has been changed to ICAO Annex 10, volume IV by amendments 86 - 89?


texts: Do bigger aircraft make a bigger sonic boom?

texts:
I was watching an episode of MythBusters where they were trying to break glass windows and cups using a sonic boom generated by a F/A-18 Hornet, flown by the Blue Angels.  In summary, they were unsuccessful at creating a boom that could shatter the windows, despite a mach speed pass within 200ft of the target building. In the last two passes they even flew straight at the building to focus the boom straight at the house, still no windows were shattered. **

But I've wondered, ever since, if they were unsuccessful because the plane was simply too small.  What if the sonic boom had been generated by a B-1 Lancer or perhaps Concorde, which are several times larger than the F/A-18?  Logically it seems that since you are displacing more air, the energy wave should have more energy.  Then again, the plane isn't going any faster, so perhaps the surface area of the wave would be larger (because of the larger plane) but you wouldn't actually have any more energy at any given point?

Anyone know if a bigger plan than the F/A-18 would have a higher energy sonic boom?  And could that cause glass to break?

Bonus point:
A mathematical formula showing why, I love those things.

For those curious about what a sonic boom is to begin with, here's a wikipedia article.

**Just to clarify, for those who have seen the episode.  A window is broken during the 200ft pass but they say that it only happened because the frame warped, not because the glass itself shattered.  Their reasoning is that only that one window broke (out of several windows and glass cups in the area), and it had a pretty cheap frame on it.


texts: How much does a passenger-to-freighter conversion cost?

texts:
Transforming a passenger airliner to a freighter seems to be common. If I understand correctly (do not hesitate to correct me), it basically consists of removing many components (seats, galley, ...) as done in the first phases of a D-check, and then the handling equipment is added (as it should be done in the late phases of a D-check for freighters).

How much does the transformation cost compared to a D-check?

Related: How much does a D-check cost compared to a new aircraft? (Useful to have an idea of D-check costs.)


texts: Missing shear pin for tow-bar / front landing gear

texts:
Sitting on the runway about to takeoff, and the captain comes over the intercom saying that we need to return to the gate.

From the quick announcement, it sounded like he said they found a 'shear pin' at the gate, or with the tow-bar, and we needed to have maintenance inspect the front landing gear.

The aircraft is an A321.

I can't imagine the shear pin was a part of the physical landing gear, but was probably piece of the tow-bar itself? I found the manual for the a320's tow-bar which shows the shear pin in the diagram on PDF page #11, item #6, within the bar assembly itself.

Why would our aircraft need to return to the gate for inspection, wouldn't they need to inspect the tow-bar instead? That says with the tug, does it not?


texts: Why would Boeing's MCAS be preferable to a modified Feel and Centering Unit?

texts:
According to some sources, the purpose of MCAS on Boeing's 737 MAX variants is to increase the back-force needed to further raise the nose when flying manually at high angles of attack, in order to give the airplane acceptable handling characteristics when approaching a stall.

Both the MAX variants and their predecessors, however, already have an elevator Feel and Centering Unit (page 8), the purpose of which appears to be the generation of appropriate stick force feedback in all stages of flight. If so, then, at first sight, this would be the appropriate unit in which to implement the function of MCAS, raising the question of why MCAS would be the preferred solution.

A few possibilities have occurred to me, but they are just guesses:

MCAS functionality needs angle-of-attack input, which may not be available where the Feel and Centering Unit is located (in the tail), and it would be complicated to get that information to it.
This answer states the the Feel and Centering Unit is a mechanical computer; given that, it therefore might not be easily modified.
Modifying the Feel and Centering Unit would require re-certifying it in toto, not just its new feature.
In addition to modifying the handling characteristics, MCAS is also seen as contributing to stall prevention directly, by reducing the angle of attack.

NB: Recently, Dominic Gates wrote an informative article in the Seattle Times about the origins of MCAS.


texts: Are animals straying onto the runway considered to be a runway incursion?

texts: Are animals on the runway defined as a runway incursion?


texts: Could "Mimiron's Head" or "flying machine" fly in the real world?

texts:
Mimiron's head is an endgame raid reward from the game World of Warcraft that's basically a cup with an upwards rotor mounted on the rear and 2 side rotors pointed downwards.

             is a video which shows what it looks like.

             shows it flying around with a pilot.

The Flying Machine, and the upgraded version Turbo-Charged Flying Machine, is a mount that a player can create themselves using the Engineering profession. It looks more like a traditional helicopter, but instead of a rear-mounted rotor, it has an engine with a propeller on each side.

             shows the Turbo-charged Flying Machine flying around.

now, to me as an aviation-illiterate person, it looks like as-is, either mount could not quite work in the real world, but if you made some modifications, they could work. Is this true? Could you make these helicopter-like vehicles work in the real world? Assume current technology or immediate-future technology (available in the next 5 years).


texts: I've read phrases like "All gas turbine engines use pressurized seals for their shaft bearing compartments to keep [...]" but I do not understand what "seals" means. In spanish we haven't a word for it.


texts:
This vessel (GOCE) is in orbit and maneuvers by using air similar to a plane to create lift and turn. The solar powered ion thrusters powers it continuously inside the atmosphere for years. Is this technically a plane, satellite, or a missile?

Source: https://space.stackexchange.com/a/33202/18879


texts: How far can a 777 fly with just one engine at altitude?

texts: If a 777 pilot wanted to fly further than with both engines running, how many more miles could the plane go with just one engine running, at high altitude?


texts: How does maximum speed vary with altitude?

texts:
Question: How does a commercial jetliner's highest possible groundspeed vary with altitude (assuming wind=0) ?

My understanding is that drag decreases with altitude, therefore maxspeed increases with altitude.

This is also what Cpt. Simon Hardy, a B777 instructor, says:

  « Aircraft [referring to airliners] go faster at altitude than at low
  level. At sea level the aircraft [referring to a B777] can only do 330
  kn. And at altitude, 30.000 ft, it can do Mach 0.86. So it's a sort of
  sliding scale – as you descend, you get slower. » (source)

But today I read exactly the opposite on an aviation blog, which I found curious:

  « When a plane gets so high, you have to fly slower, since the speed of sound (and hence true airspeed for a given Mach number) decreases with altitude. » (paraphrasing, source)

  « Real basic point: You’re flying higher, you’re flying slower. You want to go fast […] you just fly lower. » (source)

... so which is it ?

The perfect answer for me would ...
• include a graph (Y: altitude, X: maxspeed)
• include citable references

EDIT (in response to the comments below):
I specified maxspeed as the highest possible groundspeed (assuming wind=0), although I'd rather prefer not to make that distinction, because from my experience this complicates the issue more than necessary: Of course the altitude will affect the different types of speed more or less, but isn't it nonetheless possible to make an approximate statement like "higher=faster, lower=slower" and explain why that is?

EDIT2
For a concrete example, let's assume:

aircraft = B777
wind = 0 km/h (for argument's sake)
weight = typical weight of a B777 ~45min into a 9 hour long haul flight
aircraft has already reached cruising altitude

If at that point the pilot wanted to "get away" as fast as possible (let's say from waypoint IGARI), what altitude should be chosen?

Is the quoted blog post correct in saying that at an usually high altitude, the plane would fly slower, therefore it would have to go lower to fly faster?


texts: For pilots, are the procedures different between airframes with different engine options?

texts:
Lets use the B757 as an example. Engine options are PW2000 and the RB211. As I'm sure they are both FADEC engines we don't have to worry about and mechanical linkages and such. But each engine although comparable in thrust ranges have different requirements from the aircraft.

As a B757 pilot are the procedures different between the airframes with different engine options?


texts: Why has the rest of the world gone after delta wings while not the USA?

texts:
JAS Gripen, Eurofighter, HAL Tejas, Mirages, all are delta winged fighter jets.

We don't see any delta-winged fighter jets in the US inventory.

Why is that difference?


texts: How do flying wings respond to crosswinds?

texts:
Is the vertical tail the primary reason for causing landings to be skewed in a crosswind? Please explain the effect of the fuselage, the tail, or other components.

If the vertical stabilizer is the primary reason for crosswind landings, do flying wings with no vertical tails (say, the B-2) experience this issue?


texts: If both pilots are incapacitated, what happens?

texts: How do the airlines prepare for a situation where for some reason both PIC and SIC are incapacitated for the remainder of the flight?


texts:
I was just informed that the world's biggest aircraft was the Antonov An-225, and huge airplane.

That being said, I was curious what the world's biggest military aircraft was. Are there limitations such as maximum speed etc,.?


texts: Why don't the noses have the same de-icing metal surface like that of the wing's leading edge, engines, tail, etc.?

texts:
For reference, let's take the A320. The nose is painted like the rest of the body.

Image Source


texts: How are extreme winds aloft handled and how do they affect flight?

texts:
I'm looking at forecasted winds aloft on SkyVector for early next week. Specifically, I'm looking at the Pacific Ocean (routed between California and Hawaii) and notice that there are some barbs showing almost 150kt winds at FL300.

Being someone who only has experience flying in lower altitudes with wind speeds I can fathom, this brings up a few questions for me:

Is there a maximum or safe winds aloft value / crosswind for say, a 737 to fly?
How is it reasonable to deal with wind speeds this high when they're other than a direct headwind or tailwind? What if it is a direct crosswind, how is it possible for the airplane to fly without significant navigation issues (or maybe safety issues?) at velocities that high.
In general, how does the significant wind speeds found in the upper altitudes affect flight (contrasted with typical general aviation flight)


texts: Can I fly the LNAV MDA when the GPS is set up for LPV?

texts:
I am going to do my CFII checkride in a few weeks and my DPE wants to do RNAV approaches to satisfy the Non-Precision and Precision approaches tasks on the PTS/ACS.
According with the Instrument ACS an RNAV (GPS) approach with LPV minimums can be used to satisfy the precision approach task as long at it has a DH lower than 300 ft. I don't have a problem with that, the airport has an LPV approach with LPV minimum of DH 250 ft.
Now for the non-precision approach, I am going to use the same approach but flying the LNAV minima. So my question, since I haven't flown LNAV minima since my IFR training, my question is: Can I fly the LNAV MDA even if the GPS annunciator is on LPV mode? I guess the answer is yes, so, is there any consideration when doing that?
And just for future applicants, an LPV approach with greater than 300 ft DH can be used to satisfy the Non-precision approach task on the ACS (instrument ACS  page A-17).


texts: Is there a detection method available to detect a plane without using RADAR?

texts:
If we don't have RADAR, is there any other method to detect flying objects?

All flying objects disturb the air around them. Is there any method by which we can detect that this air turbulence is from an artificial flying object or a bird etc.?


texts: What advantage(s) are there for the HondaJet's engine mount position?

texts:
The HondaJet has over wing mounted engines as can be seen here:

Image from LuxuryLaunches.com
The advantages v drawbacks of the over wing mount have been discussed here and here. The over wing mount on the HondaJet could take advantage of the Coandă effect, except that they're not in front of the wing, as can be seen (above), but more clearly here:

Sourced from HondaJet.com themselves.
In fact, the placement looks like the typical rear fuselage mount, except they're not mounted to the fuselage. The rear fuselage mount is quite common in the small private/luxury jet market:

Gulfstream G550 hosted by Gulfstream

Learjet 45 image from Aviation-Times.aero
This seems to combine all the disadvantages of an over wing mount with the disadvantages of a rear fuselage mount, and neither of those positions seem to have a huge amount of advantages.
What are the advantages of a high, over/behind wing engine mounting position as seen in the HondaJet?


texts: What forces act on an airplane's door from the outside in cruise?

texts:
The inside cabin pressure from what I understand is pressurized to the values found at 6000-8000 feet high (11.34 psi at 7000 feet), at which point we can find the amount of force can be found acting against the door internally.

What about the pressures outside of the door? Is it just the pressure of the altitude of the plane acting against the door, or are there other forces involved, such as the force of the wind?


texts:
Why does the Las Vegas Airport have three control towers? I just noticed, and I find it a little weird. There should only be one... Does anybody know details on how this came about? And how they work like that?

EDIT: Not a duplicate, the question is specific to Las Vegas Airport, the other question is about another airport.


texts: Why are emergency vehicles needed for a runway excursion?

texts:
When passenger jets have a runway excursion incident such as this one in Birmingham it is apparently common practice to send emergency services vehicles to the aircraft.

Why are emergency services vehicles necessary?
I would think the plane is more than capable of getting back onto the Tarmac, so why doesn't it?


texts: Is an ekranoplan less efficient than a regular plane?

texts:
This are my conclusions upon researching the matter:

Ground effect is the cushion of air that can not escape down because of the ground. The hovercraft creates that cushion using a skirt which prevents as mush as possible a lateral escape of the air from underneath the ship. In effect a pressure differential between underneath and over the ship is created, enough to counter the ship weight. The value of this overpressure is within millibars.

Now returning to ekranoplan. While in the water, the ship has to fight the water drag. If the wings provided just enough lift to defeat the water drag, and the air cushion former under is rendered slow enough at escaping, then the ship becomes airborne. Will ride on a dynamically forming air cushion, better known as ground effect. However, the air drag becomes now the main opposing force. Increasing the angle of attack will increase the air drag and thicken the air cushion to the point where the ground effect is lost and the aircraft will loose altitude down to ground effect. Since the power output is limited, the machine is restrained at flying in ground effect only.

Now in terms of efficiency, the answer is no. The ekranoplan uses more thrust to fly in ground effect because it has to overcome air drag which is significantly stronger due to high angle of attack required to maintain the ground effect. The main reason the airplanes are efficient is due to low drag cruising. The wing develops enough lift to maintain the aircraft in the air while the angle of attack makes the wing a blade cutting through the air. Since the ekranoplan rides at way lower speeds than a regular airliner, it is required a high angle of attack which in turn determines a high drag.


texts: Is an increase in induced drag always caused by an increase in the angle of attack?

texts:
In this video at 2:57 they increase the AoA to maintain lift, which normally also increases the drag. Now, imagine that we don't increase the AoA: the drag will not increase but we will not have enough lift to maintain level flight. If we want to keep the same lift and fly in level flight we must increase the AoA and only then will the drag increase.

So induced drag is just caused by a larger AoA, so basically this is a type of pressure drag.

Do you agree that if we don't increase the AoA as described in the video then the drag will not increase as well?


texts: Why are flight simulators bad at predicting drag and lift values at high angles of attack? (the nonlinear flow regime)

texts:
X-Plane is built on something called blade element theory. From my understanding, it says the aircraft performance can be found if the performance of 2D cross sections are calculated and integrated in real time. Laminar Research (the maker of X-Plane) uses that as a selling point for X-Plane, saying it can be used to help aircraft designers try out their designs in flight on the computer before building prototypes. However, as commentators on this forum have written before (Peter Kampf), most flight simulators are bad at predicting the performance of the airframe at high angles of attack without using a table of force coefficients generated through windtunnel data or detailed CFD.

My question is, what in the flow physics drives this? What part of the physics is modeled incorrectly to give garbage data at high angles of attack?


texts: How unusual is the 737 MAX 8's crash history?

texts:
The Boeing 737 MAX 8 is getting a lot of bad press at the moment,  but people's instincts when it comes to probability are generally terrible, especially when it comes to risk assessment.

Compared to other models, how unusual is it for there to be two crashes in half of a year, of rather young planes? How much total flight time has the model had? How statically signification is it?


texts: What is the reference plane for the ILS glideslope angle?

texts:
Is a 3-degree glideslope based from the runway surface slope at the point where the antenna is installed or is it referenced to a zero-degree plane?

If you know of a design document or FAR/AIM reference, please include that as well.


texts: When should I request clearance to return to altitude, after leaving cruise altitude?

texts:
I can not understand the term”cruise” perfectly.
I know I should request ATC clearance to return to cruise altitude, if I leave cruise altitude to out side of the block.

Ex) Cleared cruise altitude 6000, MEA is 4000. The block is between 4000 to 6000. So I can descent or climb within the block without clearance. if I leave to out of block, i need ATC clearance for return to the block altitude

There are two which I am confused.
First, Can I descent/climb several times without clearance within the block or just once is possible?

Second, When I leave assigned within the block, still should I request an


texts: Do regulations require electronic checklists to be displayed on a cockpit screen or EFB?

texts: As per regulation is it required to have the checklist (Normal and Emergency (drive by any alert))  as a part of the Cockpit Display System or EFB?


texts: Why are some parts of the wings not protected by the wing anti-ice system in the B737?

texts: This picture is an explanation on the wing anti-ice system of the B737. As you see from it, the system doesn't protect the outboard leading edge slats and the leading edge flaps from icing. Anybody know why? Is it because icing on these surfaces isn't hazardous, or is it due to some limitations involving the bleed air used in the wing anti-ice system?


texts: Is "General Aviation" a well-defined term in the US, in the EU and/or elsewhere?

texts:
In this earlier question I tentatively assume that GA means civil aircraft operations other than scheduled passenger transport - what I think of as "airliner" operation though it could include quite small aircraft operating a scheduled fare-paying passenger service.

It has been suggested to me that GA can sometimes or often be used to mean all aviation in general - perhaps in some contexts more than others.

I had thought that most people here used GA to mean aircraft operations other than scheduled service, but now I have my doubts.

So, is there an authoritative definition of GA in the USA (and elsewhere, or worldwide) or is it a vague and varyingly interpreted general phrase that I should avoid to prevent misunderstanding?


texts: Why did the Ju-87 Stuka have a siren? Was this for purely psychological reasons or did it help the pilot in some way?


texts:
METAR YPJT 070300Z AUTO 10010KT 9999 // NCD 27/10 Q1018 RMK
RF00.0/000.0

In the above METAR report, I have two questions:

What does the fraction "27/10" mean?
What does "RF00.0/000.0" also mean?


texts: What is this weird format (R06L/CLRD62) in METAR for runway being cleared?

texts:
Yesterday, this metar was published:

METAR UUEE 292000Z 07003MPS CAVOK 17/12 Q1013 R06L/CLRD62 R06R/CLRD62 NOSIG=

Can someone explain the meaning of the R06L/CLRD62 R06R/CLRD62 bit? I suspect it means the runway has been cleared but I'm not sure about the details.

More generally, is there a definitive METAR specification that cover these edge cases?


texts: What is the step-by-step process to become a ground instructor in the US?

texts:
I would like to know about the whole step-by-step process to become a ground instructor in the US.

My understanding is that any previous pilot or CFI certificates are not needed. So, are only needed the FAA written tests (FOI/BGI/AGI/IGI)? And that's it? What about endorsements?

After passing the FAA written test, do I need to submit an application in the IACRA system to request the card, or it is done automatically?


texts: What are the trim settings on ferried aircraft?

texts: Sometimes an aircraft or spacecraft is ferried on top of a carrier aircraft. Do these "piggy back riders" have their flight surfaces controlled (possibly remotely) during the flight? If not, how are they trimmed?


texts: Is it legal to make emergency landing on roads?

texts: Recently I've seen many videos of planes landing on car road. Is this legal? Does this only apply to only USA or even other countries?


texts: What is the point of having lots of different flaps settings?

texts:
This question is about the number of flaps settings on different airliners. One can notice that this varies greatly between models and manufacturers. On a Cessna 172, you usually only have 4 or 5 settings.
But on airliners you have usually more, especially on Boeing.

So I did a quick search and found the following (links point on the image I used):

B777: 7 settings: 0-1-5-15-20-25-30
B737-900: 9 settings: 0-1-2-5-10-15-25-30-40
B787-8: 7 settings: 0-1-5-15-20-25-30
B787-9: 10 (!) settings: 0-1-5-10-15-17-18-20-25-30

On the other hand, Airbus seems to stick to the same scheme for its models:
 the A320/A330/A350/A380/A330 all have 5 settings: 0-1-2-3-full

The questions are:

When you have 9 or 10 different settings, what is the point of having so much ? Is that really useful ? Does the crew really incrementally uses all of them on approach and landing ?
I mean, if they only step, say from 0 to 5 on approach, then  5 to 15 on long final, and then 15 to 30 on short final, then the manufacturer could have saved some metal.
Boeing planes have more settings than Airbus. Is there any particular design reason behind that ?
Airbus doesn't designate the different positions as angles, but as incremental numbers. Anybody knows why they did that design choice?


texts: Why would a plane perform 360° turns to balance fuel on the ground?

texts: Why would a plane need to do a couple of 360’ turns on the taxi way/run-up area. The crew were given clearance to taxi and hold. They told the tower they needed to turn the plane 360’ and were cleared. When they asked for a second 360  they said they were trying to resolve a fuel imbalance issue. I think this was a Gulfstream. What was going on with this.


texts: Do ANR headsets affect pilots' perception of engine problems?

texts:
ANR (Active Noise Reduction) headsets reduce the sound level to a pilot's ears by creating an interference wave that cancels out some of the environmental noise in the cabin. Some say that this reduces the pilot's ability to hear minor changes in the engine's sound, thus delaying the point when the pilot would take action to diagnose the problem or land the aircraft.

Are there any conditions of engine malfunction or suboptimal performance which a pilot wearing an ANR headset would not be able to detect, but one wearing a passive headset would?


texts: Why is there a maximum altitude to restart a jet engine?

texts: On all the turbojets that I have flown the maximum altitude a pilot can attempt a restart is 30,000 FT MSL.  What factors go in to deciding what the maximum altitude is for an engine restart / relight?


texts: What is this aircraft on the grass in Budapest International Airport?

texts:
While taxiing after landing in BUD recently, I noticed a widebody aircraft half-hidden in the trees on the grass of the airport. You can see it on Google Maps over here.

What is this aircraft, and why is it positioned like that? There’s the fire brigade building nearby, but they already have a training aircraft a lot nearer.

More 3D views:


texts: What makes fast decompression so dangerous for the fuselage?

texts:
There have been flight accidents which involved structural failure after fast decompression of the cabin, like
BOAC Flight 781.

I'm  thinking about how decompression can destabilize or destroy the structure of a fuselage;

I would think that a hole pinched into the cabin wall of 1 cm diameter will just cause slow decompression over minutes.

I got the impression that creating a larger hole, like removing a door, can potentially cause severe failure of the fuselage in other places than the hole.

If that is the case: what makes a hole large enough to be dangerous?
And what is the mechanism making a large hole dangerous?

Or is it that the structural failure comes first, and decompression is just a salient symptom of it?


texts: Is the mach number of an aircraft measured with respect to stagnation speed of sound?

texts: I was reading chapter 8 of JD Anderson Aerodynamics when I came across something I find weird. I found out that there are different types of Mach number, based on what the speed of sound was taken as. Now my question is this, when we say "That plane is flying at Mach 1", is it with respect to the stagnation speed of sound, ie, (approximately 330 m/s), or is it with respect to the actual speed of sound?


texts: What units are used by western airliners?

texts:
Many different units can be used to designate the same things.

Degrees Celsius va Fahrenheit
Altitude in feets or meters, ...
Sometime different units measure the same thing but have different semantics or measure very similar things:
Speed can be measured in Km/h or Mach number.
Fuel can be measured in Kg or liters.

Some units can be also displayed relative to some other ones (ex we have n min of fuel left)...

What units are typically used in aircraft nowadays.

I'm particularly interested in:

Speeds
Pressure
Altitude
Distance
Weight
Volume
Position

Let's restrict the question to units displayed in the cockpit, and to Airbus or Boeing non military airplanes.


texts: Was the Buran space shuttle capable of doing a go-around?

texts: In several places I've seen reference to the Buran automated landing where it supposedly did a go-around and came in for a second landing attempt.  I was under the impression that the Buran was unpowered and therefore didn't have any ability to fire engines to regain speed (and therefore altitude) for another landing attempt.  Is this go-around an urban legend, or am I mistaken about what Buran was capable of doing on landing?


texts: How to Recover from a Spin in Cessna 172?

texts: How to recover from a spin in a Cessna 172 ? What are the different maneuvers that a pilot would have to use to to do so?


texts: What materials are plane windows made of?

texts: I've always wondered, what are those dual-layered (bonus: sometimes they have a little <2mm hole, why is it there?) windows commercial jets put next to their seats made of?


texts: What would be the ideal plane specs that minimizes consumption for 1000 kg of cargo payload (slow speed, wing span, whatever..)?

texts: Speaking of electric planes, I wonder what'd be the optimal specs if the only variable that we'd try to optimize was consumption (assuming a 1000 kg payload and 600 mile legs, unrestricted runway)?


texts: Could the Cruise-Efficient STOL configuration be as efficient as a conventional airliner?

texts:
The Cruise-Efficient Short Take Off and Landing (CESTOL) is a NASA project.  There is a video here:

The configuration is a conventional fuselage at the very front of the aircraft with enormous thick section leading edge extensions.  The wings outside the LEX appear to have similar aspect ratio to a 737 or A320.  The aft fuselage is flattened and there is a v-tail.  The engines are buried in the wings in a fashion similar to the Gloster Meteor aircraft.

How much less or more efficient would this configuration be compared to a conventional tube and wing configuration for a 737/A320 size aircraft given similar engines and materials?


texts: Does the 2020 ADS-B -Out requirement apply to aircraft with only a wind-driven generator (electrical system)?

texts:
Since my J3 Cub was was not originally certificated with an engine-driven electrical system it's clear the 2020 ADS-B-Out mandate (U.S.) does not apply (except where specifically noted in FAR part 91).

If I install a wind-driven generator providing a limited electrical system for my J3, will I now be required to comply with the ADS-B Out 2020 regulations?


texts: What are some advantages and disadvantages of have the wing on top of the airplane?

texts: Most commercial airplanes have the wings on the bottom of the aircraft to lift the body better, but what about the sugar volt concept that has the wing on the top


texts: Does a quadcopter have flight modes beyond traditional aircraft?

texts:
Quadcopters, by virtue of software-piloting rather than human-piloting, are capable of new modes of flight. I've seen one in which the machine maintains altitude despite the loss of two rotors by spinning (yaw).

I wonder about a different mode, though; if a quadcopter could maintain a very high degree of pitch, then the flight is closer to a very short 4-engine X-wing aeroplane. This would be the advantage of a tiltrotor; after takeoff, rotate into the near-vertical position and permit much higher rates as we are no longer limited by usual helicopter dissymetry of lift arguments.

Is this possible? Are there other modes beyond the capacities of traditional aircraft? E.g. yaw spinning in the forward pitch position, coast-and-burn by varying the pitch periodically to switch between gaining altitude and gaining forward momentum, etc.


texts: How common and dangerous are fume events?

texts: I’ve been hearing about fume events where engine oil containing tricresyl phosphate as an additive can leak onto the HVAC packs and enter cabin air. These organophosphate are incredibly toxic and are used in nerve gases. There are even cases where pilots have died such as here (AVHerald) and here (BBC).


texts: Where to get spatial data for ATC airspace?

texts: I am looking for free or open spatial vector data (geoJson, .shp, .kml, …) which maps the responsibilities of air traffic control in South East Asia, worldwide would be very nice too. SkyVector.com seems to have an excellent data source but its not open. any ideas? Cheers!