texts: What are the guidelines for call signs for aircraft dealing with US ATC?

texts: Suppose a general aviation aircraft is operating VFR under part 91. When they call ATC they'd normally use their tail number as the call sign. Something like "November 1-2-3 Foxtrot Uniform." What if they called up as "little piggy 27?" Are there guidelines or regulations about this? Does a custom call sign require anything or can you just make one up?


texts: What is the flight trajectory of a commercial airplane in regards to altitude v/s distance?

texts:
So, my friend and I got into an argument regarding the flight trajectory of a plane. He said that for half the journey the plane is ascending and for the rest, it is descending and hence making a parabolic curve. I argued that it ascends and then stays at the same altitude for the journey before descending to make a trapezoidal curve. After some contemplation, I think that both of us are right just that the baseline reference is different where he took it as a straight line between the two places without the curvature of the earth and hence it would make it parabolic while I took the trapezoidal curve by accounting the curvature of the earth.

We can also say it is from a different of view with him being in space while I am running on the ground to measure the altitude.

So, can someone clarify and tell who is right and whether what I think is correct or not?

It would be helpful if someone can actually plot the two graphs.
Thank you.


texts: What item is a pushback operator holding up after pushback?

texts:
After a pushback I saw the operator of the pusback truck standing next to his truck and showing the pilots a "thumbs up" with his right hand. In his left hand he was holding something up. It looked like a key or some kind of cotter.

I could imagine that it is some kind of part that he could only have if he really is clear from the plane and didn't forget to disconnect something.

Am I right? Is this some standard procedure? If so, what was he holding?


texts:
Irrespective of the stall speed, the only reason aircraft stalls is when its control surface (elevator, aileron) exceeds critical AOA. Then what is the significance of the stall speed?

Does the aircraft stall at the "stall speed" even if its AOA is less than critical?


texts: What types of aircraft perform military airlift operations?

texts:
What planes are the key players in military airlifting?

I know the C-130J, C-17 and A400M are among them, what others are there?

What are the key differences between the above mentioned planes?


texts: An instrument applicant must have 40 hours of actual or simulated time. Can some of this be flown without an instructor?

texts: 61.65 says an instrument applicant must have 40 hours of actual or simulated instrument time, 15 of which must be from an authorized instructor. What about the remaining 25 hours? Someone without an instrument rating can't file and go fly an IFR flight, right?


texts:
Is there a public and current (AIRAC-cycle 1509)  list of all worldwide victor- and jetairways (including the pertaining intersections)? I'm not searching for a graphical map of the airways, but more for a text file listing all items.

Sorry for the poor tagging, I couldn't find any suitable tag (there isn't one for "airway" or "intersections").


texts: How often does evacuation happen as shown during the pre-flight safety videos/stewardess instructions?

texts:
I believe it is mandatory for airlines to provide passengers with information about evacuation in case of emergencies. However, pretty much every accident I've ever heard off either happens at the airport (where normal exit routes are available) or in the middle of nowhere (where no passenger makes it out alive).

Is there any statistics on how often do "normal" evacuations happen among Western airlines? The only example I can think off is the Hudson landing of US Airways Flight 1549.


texts: What is the communication protocol for the side-stick in the F-16 or F/A-18?

texts: The side-stick in the F-16 or F/A-18 communicates with the flight control computer to transmit the pilot inputs. This transmission uses a protocol. Which protocol?


texts: Why does airnav list frequencies for some STARs on the airport info page?

texts: I was on airnav.com and looked up the info for KIWA. Why does airnav list frequencies for the arrivals (STARs) that serve an airport? Does each frequency correspond to a certain TRACON sector?


texts: How to identify the FAP in runway during Landing?

texts: How to identify the FAP in runway during Landing ?


texts: How do contemporary Russian jet engines compare to Western ones?

texts:
How do contemporary Russian aircraft engines like the PS-90A1 and PD-14 compare
to similar engines from GE, PW, Rolls Royce and CFM International? How many years/generations they are behind their Western counterparts from aforementioned companies? In what ways exactly they are behind?


texts: How does auto-trim work on fly-by-wire aircraft?

texts:
As I understand, you trim to reduce the effort needed to maintain the stick in the right position. Thus, you may reach steady flight before moving the trimming wheel.

In fly-by-wire aircraft (to fix things, let's consider an A320), there is no such effort to maintain as you use sidesticks. Moreover the elevator may move almost constantly (and thus always apply some effort) to compensate turbulence (enhance stability feature).

After reading this question, I understand that trim is achieved by moving the stabilizator and that in normal law it is done by the computer (we actually see the trim wheel moving alone)

My question comes in several parts:

In flight in normal law, how and when does the computer decide it must trim the plane?
What does it take into account to trim the plane (speed? flaps configuration? average position of the elevators for the last few seconds? a mix of all? I guess average position of the elevator in a sliding time window is enough)
Does it anticipate the trim (e.g. trim before or while changing the flaps configuration)?
What happen on the ground? For example during the take off roll, I don't think there is enough data to feed an auto-trim system, but I may be mistaken.
What happen if not in normal law (I guess auto-trim would be one of the feature unavailable in alternate law)?

EDIT: althought the question may seem similar to this one, it differs as my question address the decision process used by the auto-trim system to command the flight control surface, and not the flight control surface itself (the use of stabilisator as trim in the A320)


texts: How do you check the correct operation of the rudder when it's tied to the nose wheel?

texts:
Preflight checklists often contain the item

Flight controls: Free and correct

However, if the rudder is tied to nose-wheel steering, is it even possible to check if the rudder is correctly connected (unless have a rear window and can see the rudder during taxi)?


texts: Can I land a plane in a field in the UK and Republic of Ireland?

texts: So I already saw this question here for the US, but I live in the UK and quite close to the border with the Republic of Ireland (ROI). We have property over the border in the ROI and I was wondering if I could fly back and forth by using the fields to take off and land in a small plane like the SD-1?


texts: Why does the U.S. have so many general-aviation aircraft?

texts:
In a comment on my previous question about the paucity of South Korean general-aviation aircraft in the 1990s, @Pondlife pointed out (in response to my comparison between the numbers of GA aircraft per capita in South Korea and the United States) that, in their words:

  Considering that just over 50% of the world's GA aircraft are in the US perhaps you should be asking why the US has so many, rather than why South Korea has so few? :-)

Why does the U.S. have such an extreme abundance of general-aviation aircraft (210,000 out of the total world population of 416,000 GA aircraft in 2016, according to the provided link), amounting to one GA aircraft for every 1,540 U.S. citizens (a per-capita abundance more than ten times the global average of one GA aircraft per 17,950 humans)?


texts: When is Minimum Safe Altitude Warning triggered?

texts:
I know that Minimum safe altitude warning (MSAW) alerts ATC and pilots if an airplane is under the risk of controlled flight into terrain.

But when is this alarm triggered? What is the minimum altitude for it to trigger? If a plane is landing, should it be triggered just before landing?

It will confuse ATC if every plane that is landing triggers that alarm.

There must be some limitations. So, what are they?


texts: Why do the two different "ground effect"s used by aircraft and automobiles do opposite things in almost the same conditions?

texts:
I found How come the ground effect has such a different outcome for wings and cars? and:
I am not allowed to comment as a new user because of some weird rule and I do not know enough to answer the question as I searched the web to find the answer to this.

Everyone is explaining that the two types of "ground effects" have the same name but are two entirely different phenomenons, but no one seems to have answered the question properly, at least that I can understand. It is all well and good saying they are different effects for different purposes but that does not explain why the two opposite effects occur in such similar conditions. I was originally searching for the answer to this question strictly in the context of car design - why the car-context ground-effect sucks the car down using the venturi effect yet having a full teardrop shaped car is meant to be impractical for the reason of creating a lifting air cushion underneath, though someone may think that the curve towards the ground would act as a venturi and suck the car down. The question is: "why do the opposite effects happen in such similar conditions". Venturi effect or air cushion? What decides which occurs?

I think aeroalias' answer sort of explained it but not in a clear and direct way; venturi effect occurs until the venturi is so extreme that the flow is "choked" and the venturi effect ceases to operate and you just have an air cushion? Is that the answer?

edit: This might make it clearer as to what I am asking though it is mainly a rephrasing of what I have already asked:

Why isn't an air cushion formed underneath a car (like with the aircraft) when the underside is curved towards the ground? Does the venturi effect occur when the curve is shallow but an air cushion form when it is steeper and flow is "choked"? I think I understand the basic theory of the car ground effect but what causes the aircraft ground effect and what conditions determine whether upward or downward force is produced?


texts: What causes the phenomenon that pilots don't believe their instruments, while they're working well?

texts:
I read in a comment on another question that pilots not believing their instruments while they work perfectly well is common in aviation:

  The flight leader reported that his compasses had failed [...] but there is a thin line between believing that your compass has failed and it actually failing. Not believing the instruments, when they are working perfectly well, is a well known phenomena in aviation.

Why is that?


texts: Are Lycoming O-360-A4M engines generally known to have right magneto issues at low power settings?

texts:
TLDR - I am renting a PA-28 181 (engine Lycoming O-360-A4M), and have noticed that the right mag is rough at low power settings. During before takeoff power checks, both magnetos operate as expected, but when making dead cut checks both after start and prior to shut down, the right mag consistently runs rougher than the left - is this normal behaviour?
CONTEXT - I've been told, by the club that I am renting this aircraft from, that the engine has always been like this, and that it is characteristic behaviour, but I've been becoming a bit more dubious as the problem seems to be worsening, and I will now often get backfires and VERY rough running (600-900 rpm) on the right mag during dead cut checks. The left mag runs perfectly smoothly during dead cut checks at about 1100 rpm (I conduct dead cut checks with the engine at 1200 rpm for reference). The engine also seems very reluctant to settle at 1200 rpm before power checks are conducted, and consistently jumps between running fast at 1500 rpm and then running unevenly at about 900 rpm. After power checks are made, the problem seems to rectify itself, and the engine will happily run at 1200 rpm.
FIXES - I can't find anything in the POH with this set of symptoms, and dead cut checks do not specify maximum rpm drops / tolerances (although for reference, I can tell you that it is uncomfortable sitting in the plane when the right mag is isolated during dead cut checks). Carb heat issues can be largely ruled out, since I always check this on the ground. Fouling seems unlikely given that the plane is always leaned for taxi, usually leaned at cruise, never flown especially high, and never flown or taxied at low power settings for extended periods (it flies out of a small airport, and off block to take off time is never more than 5 minutes).
I've mostly flown the PA-28 161 rather than 181, and have not flown enough different airfames of this type to know if this kind of anomaly is harmful or not, although another pilot not from this club has expressed concerns. I would much appreciate any advice!


texts: What navigation systems were used by the Space Shuttle during reentry?

texts:
What equipment did the Space Shuttle orbiters carry to support navigation during reentry?
Were there any differences between the individual orbiters in this regard?


texts: What is preferred in an emergency landing: a road or a cornfield?

texts:
When faced with the situation of a power off emergency landing, how do you best select your location to land?

At what point is a road too small or the crosswind too great to attempt a safe landing and instead select a corn field or such? Should the road even be considered?

EDIT: Also, how does plane size and build factor into the decision?


texts: Would cone shapes grills in front of jet engines prevent damage in case of a bird strike?

texts: If cone shaped grills pointing forward were in front of jet engines would they make bird parts slide outside towards the back of the engine and away?


texts: Can a helicopter operate continuously in a small, enclosed, sealed environment?

texts:
Many years ago I had an interesting discussion with a friend (while drinking). We were discussing what would happen if a helicopter was placed into a sphere of some size (slightly larger than the helicopter, a few times larger than the helicopter, etc.). Assume the sphere is filled with air at standard temperature and pressure, and there is standard 1G gravity pulling in one direction.

Can the helicopter maintain flight?

I believe it might, for a very short time, until the air starts circulating in a (relatively) stable manner, causing the "natural flow" of air to be already descending when it encounters the rotor disc, therefore reducing lift to nearly nothing.

I'm curious what an expert might think. If this is off-topic, mark it as such and I'll delete the question. Adding more useful tags I don't know about might also be helpful. :)


texts: Why are most runways made of asphalt and not concrete?

texts:
From the little I know about vehicles in cities, nowadays concrete is preferred to asphalt for road construction as, while initially more expensive, concrete is supposed to be cheaper to maintain.

From a recent reading I understand India also uses asphalt in most places.

I have two questions:

Why haven't airports switched to concrete?
How can I check online the type of material used for passenger commercial airports around the world, especially transit hubs?


texts:
I know that the strobe lights that flash in rapid succession of each other indicate the open end of the runway, to help guide pilots in at night. It's obvious the white lights indicating the edges of the runway. And I'm guessing the green lights at one end, indicate the open end, whereas red lights at the other end indicate you are approaching the end of the pavement.

But what are those lights at the ends of runways on (typically red) poles. Typically in large sets with one set on either end? Are these just to help the pilot line up? I would assume the actual runway edges and center lighting would assist with that?


texts: What are the holes on the top side of the canard of Eurofighter Typhoon for?

texts:
The Eurofighter Canard has some holes on top side. What are these holes for?

?


texts: Who has final authority over Air Force One?

texts:
U.S. FAA FAR 91.3 ("Responsibility and authority of the pilot in command") says that:

  The pilot in command of an aircraft is directly responsible for, and
  is the final authority as to, the operation of that aircraft.

When an aircraft is operating as Air Force One, it would normally be flown by the designated high ranking USAF Officer, as a military flight.

Is the President, as Commander in Chief of the armed forces, able to over-ride the authority of the pilot?

For example, if one of the current Boeing VC-25's engines flames out and the captain announces that he has made the decision to take an option/ turn back - can the President override this decision and force him/her to continue the flight?


texts: What is this jet aircraft appearing in the 2019 TV Series "Black Summer"?

texts: This looks like an F-22 Raptor, but I can hardly see it:


texts: Do I need a waiver to operate a C208B with more than 9 passengers?

texts: Do I need a FAR Part 23 waiver for more than 9 passengers if I'm operating a Cessna 208B Grand Caravan under part 91?


texts: Can I generate & transmit ACARS message via software?

texts:
Is there any software available for generating ACARS message? If yes how to transmit that over RF?.
I want to do that for academic purpose. My settings are GNU radio and HackRF one.


texts: At what point does the throttle control RPM on a constant speed prop?

texts:
On an airplane with a constant speed prop, the prop lever typically controls the RPM (pitch) of prop, and the throttle controls the power, measured as Manifold Pressure ("MP"). However, at low power settings with the prop lever full forward, there is a point where the throttle control begins to act like a throttle on a constant pitch airplane where the throttle controls the RPM. This is the point that I'm asking about.

Does this point occur at the same MP on all aircraft? Conceptually I understand that when the prop is set to max RPM the prop will adjust pitch finer and finer as I reduce power until it gets to the point where it can't flatten out the pitch anymore as I continue to reduce power, then the RPM will begin to drop. Is this a point that is specific to engine/prop combination or is it adjusted by mechanic?


texts: What are the differences in aircraft performance between tractor and pusher propeller designs?

texts: Some aircraft have pusher type propellers.  In what ways is it different from a tractor type propeller?  What's are the advantages and disadvantages over a tractor type.


texts: What do the tail numbers on aircraft mean?

texts:
Could someone please tell me the meaning of the alphanumeric numbers on aircraft's tails?

What exactly does the SB 023 mean for this Indian Sukhoi-30 MKI aircraft?


texts:
Rutan Voyager had a very long flight.
Did pilots have a separate toilet room for when they needed to relieve themselves?
How much room did they have to move around anyways?
Is there any visual with the interior of aircraft?


texts: Why are flights from Fuzhou or Xiamen to Taiwan not allowed to overfly Taiwan strait?

texts: The flights from Kinmen or Matsu to Taiwan always overfly Taiwan strait. Why can't the flights from Xiamen or Fuzhou use the same route, fly over Kinmen or Matsu first and then to Taiwan directly, but need to fly away from the strait?


texts: What is the offset in a seaplane's hull?

texts:
I noticed there is a little offset in a seaplane's hull (highlighted in the following picture). I suppose this is useful as it exists in all the seaplanes I know.

It appears to be neither a hydrodynamic nor aerodynamic feature. I could not find clue by myself as I don't know this feature's name.

My question, what is its name and purpose?

(wikimedia.org)


texts:
Wouldn't you think they'd choose HL instead?

That might confuse pilots who frequently see SS (Sandstorms),
 DS (Dust Storms) and VA (Volcanic Ash).


texts: Can current fighter jets perform a deadstick landing?

texts: If a current modern day fighter were to have a total engine failure over a suitable landing site or airport, can the pilot safely perform a dead stick landing? If so, are they routinely given training for the procedure?


texts: Does the sound barrier apply to a silent aircraft?

texts:
For my summer duty, I was looking at the sound barrier effects with a glimmer of hope to understand them:

"A supersonic aircraft is one that can travel faster that the speed of sound. As the plane approaches the speed of sound, it catches up with the sound waves traveling in front of it and pushes them up against each other. The result is a barrier of squashed air in front of the aircraft." Source

Is it theoretically possible to design an aircraft totally silent or at least quiet?

In that case would the problems associated with transonic/supersonic speeds disappear, or at least are reduced?

  As the plane approaches the speed of sound, it catches up with the sound waves traveling in front of it and pushes them up against each
  other.

Or is there a silence barrier too?


texts: Is the "effective wing span" reduced in a turn?

texts: The Ace the technical pilot interview book says that in a bank the aircraft's lift is reduced due to an effective reduction in wing span. I know in a bank the vertical component of the lift vector is reduced due to the inclination of another component of lift towards the banked side. So the overall lift required to counter the weight is increased. That's why we need to increase the AOA or speed to maintain a level turn. But I am a bit confused about how the effective wing span is reduced, can anyone explain?


texts: How can one quickly estimate interference drag for a configuration?

texts:
I'm doing some work on streamlining my process for designing new aircraft, and in the process creating/looking for rules of thumb and shortcuts one can use when designing. I'm currently in the process of creating a way of quickly estimating L/D of an aircraft in conceptual design stage. I'm looking for something that doesn't involve a ton of CFD or windtunnel time, and can be incorporated into a spreadsheet. It needs to be +/- 10% of the actual L/D achieved.

I've been able to figure out lift and drag of individual components pretty easily. However, I'm having trouble with figuring a quick way of estimating interference drag. What shortcuts do experienced designers use for estimating interference drag quickly?


texts: Why are fighter jets equipped with dorsal fin?

texts: I don't really get whats the purpose of dorsal fins and what they do with the flow over the vertical stabilizer. I noticed on most single tail configured aircrafts are equipped with a dorsal fin like the f 16.


texts: What is the largest (size) solid object ever dropped from an airplane to impact the ground in freefall?

texts:
What is the record for the largest single solid item that has ever been dropped from an airplane at free fall to the ground?

Here, "free fall" means falling vertically, or nearly vertically falling allowing some leeway for expected horizontal movement such as the ground speed of the plane doing the drop, winds, or unintended Magnus effect among other things, and allows for normal atmospheric air resistance.
The object being dropped should be payload, not part of the vehicle doing the dropping.
The object should not be designed with the intent to generate lift. For example, the above mentioned Magnus effect would disqualify if a machine was purposely built to spin with the intention of generating lift. This includes things with wings, parachutes, landing thrusters, etc.
The object must have hit the ground in an uncontrolled descent in the past. In other words, satellites in free-fall orbit around the Earth do not count unless they fell to the ground and then got re-launched into orbit again (unlikely).
Objects that burn up in the atmosphere do not reach the ground as a single solid object, so they do not count unless any possibly remaining fragment that may reach the ground is still the biggest object to be dropped and reach the ground in its destroyed state (unlikely).
The item does not have to have been intentionally dropped. For example, if it were dropped with a parachute, but the parachute failed to deploy, that counts.
Bombs easily count as long as they don't have a parachute, thrusters, wings or any other design factor that is intended to generate lift.
Last, but not least, "largest" means greatest volume, not heaviest.


texts: Do passengers notice if the aircraft is struck by lightning?

texts:
I recently saw a video from Valk Aviation
(actual scene)
of a KLM B777-300 struck by lightning on departure. It happened a few days ago.

I know this looks more frightening than it really is and the aircraft usually isn't harmed. There are numerous posts here covering this.

But I wonder what a passenger would notice when the aircraft gets hit? Is there some kind of BANG or something? Do the lights flicker, for example?

Terrys answer implies you cannot tell for sure so I guess you won't notice at all. Is that true?


texts: How can I convert a non-ICAO (Taiwanese) pilot's license to FAA or EASA?

texts:
So I'd like to know from somebody what's the process of converting a non-ICAO license. In particular, I'm trying to understand how a Taiwanese PPL can be converted to FAA PPL (I personally know people that have done it).

Taiwan is not a member of ICAO due to it not being recognised as a country due to China. So does that mean that a Taiwanese license is considered as a Chinese one and maybe that's why the FAA does the conversion?

I'd also be interested to hear about anyone who has tried to convert to EASA. I've never heard of anyone doing that.


texts: How are fly-by-wire airliners controlled in case of complete electrical failure?

texts:
In this comment, it is postulated that even fly-by-wire aircraft (Airbus) are demonstrated to fly without any electrical systems.

  All Airbus aircraft are demonstrated controllable with complete electrical failure. They would be pretty difficult to land if the electronics didn't at least partially recover (because the backup only allows controlling pitch and yaw and roll only via yaw-roll stability), but it would still be possible. [...] Jan Hudec Dec 21 '14 at 21:38

My question, assuming complete electrical failure, how exactly is this done? What controls have mechanical linkage (pitch trim? engines? flaps/slats?) Would it be possible, in theory, to land the plane in such a way that some passengers could walk away? (Perfect weather, miles of flat tarmac runways everywhere, cinematic pilot capabilities)


texts: Does wing with bell lift distribution has negative lift at tips?

texts:
Does wing with bell lift distribution has negative lift at tips during cruising flight?
Looking at this diagram, tips has very small lift but it is not negative.

https://ntrs.nasa.gov/citations/20180004462  open pdf


texts: How can the lift induced drag for a wing be calculated?

texts:
I have found a lot of information to calculate drag coefficients and I know that total drag can be calculated by
$$ D = \frac{1}{2} \rho u^2 S C_d $$
However I was wondering, if I substitute the zero lift drag coefficient into this equation is it correct to assume the value produced for the drag force would be the parasitic drag whilst the remainder of the total drag is made up of lift induced drag?


texts: How do I maximize flight hour usage in getting an instrument rating?

texts:
I recently finished a private pilot certificate and I'd like to get a instrument rating while keeping my costs low.  I understand I'll need 50 hours of cross country PIC time (VFR) and 40 hours instrument training.
Question:  If I fly under the hood with a Safety Pilot on cross country flights for 15 hours, do those 15 hours count both towards the 50 hours of cross country PIC time and towards the 40 hours of instrument training time?
Here is the breakdown of what I think I would need:
50 hours cross country PIC time consisting of:
15 hours cross country PIC time I already have,
15 hours cross country PIC time while under the hood with a Safety Pilot, and 20 hours cross country PIC time solo (or with a friend).
40 hours instrument training, consisting of:
4 hours already completed with instructor (3 from PPL),
15 hours under hood with Safety Pilot,
10 hours with instructor in Redbird simulator,
and 11 hours with instructor in airplane.
Am I getting this right?


texts: What is the optimal wing sweep angle for a passenger airliner?

texts:
There are many different types passenger planes, but is there a optimal wing angle for these planes, that improves the plane's take off speed for example, or the fuel efficiency

The Boeing 747 has a wing seep angle of 37.5 degrees, the Airbus A380 has a wing sweep angle of 33.5 degrees. These are two of the largest planes in the world. So is the optimal range for a wing sweep angle between 33.5 and 37.5 degrees, or are there certain regulations stating different sweep back angles that a passenger airliner can use.


texts: On a bypass engine does the bypass air travel faster or slower than core air?

texts:
Using the convergent /divergent duct theory the low pressure cold stream bypass air would travel faster but I read on a web page that the bypass air travels much slower than core air. But again using the convergent / divergent duct theory core air is subject to higher pressures and temperatures therefore should theoretically travel slower?

Or is it because air is mixed with fuel and accelerated during combustion which makes the core speed faster and Bernoulli converging / diverging duct theory I stated above doesn't apply?

Hopefully someone can tell me if I'm thinking this incorrectly... Simple explanation please and not something over complicated.

Thanks!


texts: Strange plane-shaped object at UK airport

texts:
A friend sent me the following image, spotted at an UK airport. Do you have any idea what that might be?

It looks a bit like MD-11/DC-10 transport case, but i have no idea. Is something like this used to transport airplanes?


texts: Has there ever been an aircraft with three sets of flight controls?

texts:
On every aircraft I know, there is either one set of flight controls if it is single-pilot operated, or two sets of flight controls allowing either the pilot or copilot full control.

Has there ever been an aircraft that has three or more sets of flight controls?

To clarify:

"aircraft" includes fixed-wing, helicopter, powered lift etc.
remotely operated aircraft do not count.
A set of flight controls consists of yokes, pedals and/or sticks that allow the operator to manipulate the pitch, roll and yaw axes.


texts: Why are the guns on the AC-130 not mounted on the underside of the aircraft?

texts: Why must the guns of the AC-130 be on the side forcing the plane to circle the target. Would it not be more practical to have the guns underneath the plane shooting downwards?


texts: If the landing gear is stuck in an airliner, can the crew go down and manually open it?

texts: There are several instances where we see the landing gear getting stuck before landing. In these kind of situations, can the crew, or one of the pilots, go down to the landing gear area and solve the issue?


texts: Why does the NASA GL-10 Greased Lightning run on diesel?

texts:
I've been reading about NASA's experimental GL-10 Greased Lightning tilt-wing aircraft with interest.

My understanding is that this is a diesel-electric hybrid aircraft uses stored electrical energy to satisfy the much greater need for thrust during takeoff (and landing?), but for regular flying runs off fewer propellers powered by the 2x 8hp diesel engines (which presumably also are recharging the Li-Ion batteries for the next takeoff/landing) to achieve better efficiency.

The answers to this question show that diesel engines are generally poorly suited to aero applications, generally due to weight and complexity.

Why then does the GL-10 use diesel fuel instead of more common aero fuels?


texts: Are the cockpit and crew rest area considered part of the cabin?

texts:
A few days ago, a travel blogger wrote about smoking on a China Eastern flight, and the smell of cigarettes came from either the cockpit or the crew rest area:

  So I’m not sure who is smoking, though I have to assume that it’s
  either the pilots in the cockpit, or otherwise the flight attendants
  in the galleys and crew rests

The CAAC's (Civil Aviation Administration of China) decree #71 banned smoking in the cabin and toilets in domestic and regional (HK, Macau and Taiwan) scheduled flights, as well as smoking in non-smoking areas and toilets for international flights. The major Chinese airlines don't have smoking areas on international flights anyway.

In reality, many pilots and first officers on Chinese airlines smoke in the cockpit, regardless of whether it's a domestic or international flight. It seems that the cockpit and crew rest area are not part of the cabin according to Chinese standards.

Are the crew rest area and cockpit considered as part of the cabin according to ICAO?
Does any major civil aviation authority consider them to be part of the cabin?


texts: What does pre/post modification mean in Airbus MPD?

texts: What is the difference between POST MOD (with partial mod i.e SXXXX) and PRE MOD (with partial mod) in the applicability column of an Airbus MPD (Maintenance Planning Document)?


texts: Can a steady flow have stagnation points?

texts:
I am confused by this idea. If a flow is steady, its streamlines are unchanging. Taking the typical example of an airfoil, there is (at least) one streamline which will hit the leading edge of the airfoil and stagnate. Stagnation point is defined as:

  a point in a flow field where the local velocity of the fluid is zero.

Now my question is, if the velocity here is zero, and fluid particles that pass through the streamline which results in a stagnation point have nonzero velocity upstream, where do these fluid particles go? Since they are on the streamline, they have to reach the stagnation point? Does this not defy the conservation of mass law?

Further, an online Fluid Mechanics course I have been following has in one lecture shown streamlines going away from the stagnation point. If the velocity at this point is precisely zero (and is unchanging since the flow is steady), then how can the fluid particles go in other directions?

I must be missing something, do enlighten me.


texts: I saw a youtube video (from a channel called Real life guys) where gum was used to join the ribs of their homemade plane to the skin and I saw another video where the wing skin(tedlar) was literally sown to the ribs of the wings,my question is what is the appropraite way to join the  wing skin(tedlar/mylar)to the ribs?


texts: What are the costs and labour hours for converting a B767 airliner to an aerial refueling aircraft?

texts:
To win the tender of RAF Future Strategic Tanker Aircraft, Boeing, BAE systems and British Airways formed Tanker Transport Services Consortium to offer air-to-air refuelling to military jets, using converted aircraft based on the B767 passenger jet. BA would provide the aircraft, Boeing would provide the conversion technology, and BAE systems would perform the majority of the aircraft modifications.

Roughly speaking, how much does it cost and how much labour hour is needed to convert a B767 airliner to military aerial refueling and strategic transport aircraft?


texts: How common are gear-driven or belt-driven superchargers in modern aircraft?

texts:
How common are gear-driven superchargers in modern piston-engine aircraft, either alone or in combination with exhaust-driven turbochargers? What are some examples of modern aircraft that use them? Is it a technology that essentially went extinct in the aviation context with the last of the piston-engined fighters, bombers, and large airliners? Such that turbocharging alone (or other variants such as turbonormalizing) is the preferred technology for piston-engine aircraft now?  (Besides the old standby of normally aspirated engines of course.)

How about belt-driven superchargers-- do any aircraft have them?  If so, which ones?

Feel free to consider homebuilt aircraft, experimental aircraft, lightsport aircraft, and automotive conversion engines in your answer.

Edit: in light of a recent comment, I'll add that I'm asking about devices that are used at least in part to increase thrust and power by feeding pressurized air to the engine, rather than only to pressurize the cabin.


texts: Can instruction be given during a flight conducted under 14 CFR 135?

texts: Let's suppose that a flight is being conducted under 14 CFR 135. The airplane is certified for single pilot operations, but two pilots who are both rated as PIC on the 135 certificate occupy the pilot seats. One of the pilots is a CFI. Does anything in 14 CFR 135 prevent the CFI from giving dual given time to the PIC while he flies?


texts: How is the glide ratio affected when converting a wheeled plane to floats?

texts:
I'm looking for published data that describe the effect on glide ratio when an aircraft is converted from wheeled to float configuration.  I suspect that the glide ratio goes down considerably due to all the drag from the floats and attachments, but an internet search turned up nothing.

I'm particularly interested in DeHaviland Beavers and Otters (which commonly have their gear switched between wheels and floats), but any source would be appreciated.


texts: Does the CF6 use Pneumatic Reverse Thrust from the APU's bleed air?

texts: Does the A330's engine (the GE CF6) use only pneumatic power from the APU for reverse thrust? Please explain detailed. Sorry for my English.


texts: What is in the A320 Smoke and Fume checklist?

texts:
What does the "Smoke and Fume Checklist" for the Airbus 320 series look like?

Is it a printed item or is it on the ECAM screen?


texts: Is there a set of laws which govern international flights?

texts:
A few years ago, my brother and I were aboard an Emirates flight from Australia to New Zealand. At the time, I was 16 and he was 14.

At one point in the flight we were both offered alcoholic drinks. Considering the drinking age where I am from is 18, and ID is required if you look under 25, this came as quite a surprise to the both of us.

Considering different countries have different laws and aircraft often have multinational crew and passengers, what laws govern international flights?


texts: Was this 'load-balancing' seat change refusal real?

texts:
On Sunday, I was on a flight in Greece, on a A320. I was sat just forward of the wings. Someone sat in the isle seat opposite me, asked if she could move to the back to sit with her friend, since the seat next to her friend was free.

The cabin crew member said she'd check with the pilots, as the flight was almost full and carrying maximum fuel... strange. She then returned and said she couldn't move seats as it would affect the 'balance of the aircraft'.

I find it hard to believe a roughly 200lb human could affect a 183,000lb aircarft in any tangible way, but I wanted to ask if this would be a real reason for declining such a seat change?


texts:
(wikimedia.org)

What is this feature on a Piaggio P.180?

I believe it's called a dolphin tail, but why is it exactly there and what is it for and why don't all airplanes have this?


texts: How does a linear acuator in flight control work?

texts: I see that the linear actuator moves the rudder but how? Thanks!


texts: How do I distinguish 2 fixes with the same name?

texts:
I see two fixes in the CIFP file that have the same name PERSN.

Given 2 fixes that have the same name but are located in different regions (defined by ICAO code) how does airplane/pilot distinguish between those 2 when respecting flight plan?
According to FAA Procedures for Handling Airspace Matters

  e. AIM [Aeronautical Information Management]  must  not  duplicate  any  radio  fix, waypoint,  marker  beacons or  compass  locators names.

how come that those fixes have the same name?


texts: Has there ever been a US airport with identifier PM2?

texts: I have an old entry in my logbook having landed and departed from an airport with identifier PM2. I think I either can't read my handwriting or I made a mistake because I can find no record of such an airport ever existing. Does anyone have a way of finding out?


texts: What are these windows/portholes on the English Electric Canberra bomber?

texts:
This may be an obvious question, but I don't know, which is why I'm asking here. I've searched "Canberra canopy porthole" and "window", but didn't get any information. There is a porthole of sorts on the left side of the canopy of this bomber, I'm wondering what it's for.

Photo source.

Here is a view from inside the cockpit:

Photo source.

There also appears to be a similar thing on the bottom of the nose of the aircraft, offset to its right. The following is a screenshot from a video game, as I wasn't to find a photo of this.

I'm tempted to say that this second one is to do with bomb sighting, however if it weren't there, the bomber would have just as good a view, wouldn't they?


texts: In case of transponder failure, can I use my ADS-B out (Stratus II) serve as a back-up?

texts: When the transponder fails, would ATC pickup my altitude response from my Stratus or any other ADS-B out instead? Is it legal to do so?


texts: Could someone please explain why the A320 doesn’t have an anti ice system for its vertical and horizontal stabilisers?

texts: I had come across in the FCOM that there is no anti ice system for the vertical and horizontal stabilisers while looking at the schematic diagram. I find it very strange that the other surfaces on the empennage do not have anti-ice systems.


texts: Can i create a home built aircraft with this engine?

texts:
http://www.chiefaircraft.com/da-100.html
Would this engine work for a homebuilt ultralight aircraft? I am still in the research phase, so i don't know what the weight of the aircraft will be, but I would like to know what a good prop size and max weight that it will be able to fly.


texts: What is the purpose of extending one degree of flaps (perhaps with spoilers)?

texts: What would be the use of one degree of flaps? And is there any reason to use both flaps and spoilers combined?


texts: How to create a simple forces diagram using only lift and drag forces?

texts:
I would like to create a simple forces diagram (like a sketch). The lift produced by the wing depends upon to the distance from the the longitudinal axis, but, in order to make it easier, I’m taking the lift as a constant in the whole wing. Here is the question, I need to calculate the moment produced by the wing taking only the drag and lift forces by the wings, what distance should I take?

Although I think the answer will be a percentage of the wingspan, here is some data if needed.

Wingspan: 1m
AR: 11
Wing configuration: tapered
Root chord: 0.17m
Tío chord: 0.12m

Sketch

Since I have the drag and lift forces and Cp, I need to calculate the distance from the x axis to this force application points. How can I estimate those distances?


texts: How do pilots detect fuel contamination in flight?

texts: According to the Aviation Herald, an Alitalia Airbus A330-200 diverted en route "reporting fuel contamination".  How can the pilots detect fuel contamination in flight?


texts: Do the effects of turbulence change when banking/turning compared to level flight?

texts:
Are the effects created by turbulence on the aircraft different when the aircraft is banking or in level flight? By logic I'd say yes but I would like some technical and practical explanation.

When in level flight I can imagine that the aircraft is moved laterally or vertically. What happens when these forces are applied from turbulence when  banking?

What are the consequences of turbulence having the aircraft banked, for example, on the lift produced by the wings?


texts: How to use a set of Pressure Transducer to mimic pitot static tube for VTOL vertical airspeed indicator?

texts: May i know if i have 3 pressure transducer, 1 facing upwards and the other downwards to measure the vertical velocity of a VTOL (Vertical Takeoff and Landing aircraft) and another 1 on the nose of the aircraft, do i still need a pressure transducer to mimic a Static port to measure the climb rate? Since i already have 2 pointing upwards and downwards. For your kind advise, thanks!


texts: Why would the digits fade out and blink in darkness on a KX-155?

texts:
I have a radio installation with two KX-155 Nav-Comms.  These radios are equipped with a photocell to automatically dim the displays to match cabin lighting.  In dark lighting, the digits fade to the point of unreadability, with some segments being visible and some not.  I can brighten and read the displays by aiming a flashlight into the photocells.
It seems like there is a bias set incorrectly or an excitation voltage which is wrong.
Why might this be happening?


texts: How to figure unusable sectors if the VOR is not colocated at/near an airport?

texts:
Stemming from Why am I not getting the "TO" VOR flag as I think I should?
If a VOR is not colocated at an airport (i.e. not in that airport's chart supplement page), how does one figure out the unusable sectors if they plan to use said VOR for off-airway (IFR or VFR) navigation?
I don't think it's been asked before.
Optional: Given that it's very common, why aren't those sectors just depicted on the charts?


texts: What were to happen if deicing fluid went in to the jet-engine?

texts: What were to happen if deicing fluid went in to an engine. I have heard that deicing fluid is somewhat flammable. What were to happen if it went in to the engine? Would it combust like fuel?


texts: What classes of aircraft require hydraulic flight controls?

texts:
All commercial airliners such as the Boeing 737 or Airbus A320 or heavier aircraft require an hydraulic system that can power actuators, which generate the required forces to move the control surfaces in all phases of flight. Smaller General Aviation aircraft do not need this.
But what about aircraft in between? Is there a minimum MTOW above which aircraft are required to or generally have an hydraulic system? Can you make examples of lighter aircraft which have it?
For example I was wondering about the an aircraft like the 19-passenger commuter Beechcraft 1900:


texts: How does sideslip indicator react during crosswind?

texts:
I will basically consider two types of sideslip indicator: the yaw string and the marble/ball inside a curved tube. I don't know the exact aeronautical term for both and I don't know if other sideslip indicator exists.

The pilot should maintain no sideslip, i.e. keeping the string centered. Let's say the pilot is able to do it. What happen in case of cross wind? Considering the air mass as frame of reference, the aircraft fly straight forward, but considering the earth as frame of reference, the aircraft is flying a bit sideways (crabbing). Thus the yaw string and the marble/ball may disagree. Am I right?

Going further, if the aircraft fly straight forward in an airmass (no sideslipping) with winds and gusts, the aircraft will experience sideways accelerations. How will the marble react? Will its indication still be reliable?

EDIT: Given comments and answers, I need to provide an extreme situation: the constantly increasing crosswind. The air mass is no longer an inertial frame of reference. Keeping no side slip result in an increasing crabbing. My understanding is that the ball should react to this increasing crabbing (sideway acceleration relative to an inertial frame of reference) but not the string (no side slip relative to the air mass)


texts: Is there a way to find a daily list of commercial flight diversions that have occurred?  If not, is there any way to compile one from available data?  Extra points if you can also get the reason.


texts: What is required to fly over Cuba enroute to another country?

texts:
I understand that you need to get an overflight permit before entering Cuban airspace, even if you aren't landing there.  How do you go about getting permission to overfly them enroute to another country?

Updated now that flights to Cuba are allowed by US operators.  What has changed, and what are the requirements now?  Can we pay them directly yet?


texts: How can I calculate a flightpath given a set of waypoints?

texts:
I have made a GUI that allows the user to create waypoints defined by latitude, longitude, altitude, and time-of-arrival. I'm looking for some software that can generate a flightpath between the waypoints.

For example, say that I have placed 5 waypoints. All that I know is that I want my aircraft to be at those five points in space at the times specified. To create my 'flightpath', I want to calculate the latitude, longitude, altitude, pitch, roll, yaw, and velocity of the aircraft as it moves from one waypoint to the next. I'd like to calculate those values for time intervals of, say, one second.

I've made a hackish solution, but it isn't very realistic. Someone must have tackled this problem before. Does anyone have any suggestions on software or algorithms I can use?


texts: Why are push-propellers so rare, yet they are still around?

texts:
Jet engines are by their very nature push-engines, however, most propeller airplanes use pull-engines. Is there an inherent advantage to using pull-propellers except for the increased airflow over the fuselage and tail (with its rudder and elevator)?

Twins generally have their engines on the wings, and the tail is no longer directly behind it, does that mean the choice of a pull-engine is not as advantageous?

If there isn't an inherent disadvantage, why are pusher configurations so rare? If there is one, why do they exist at all? Disregarding designs where the choice is obvious, like powered parachutes where you simply don't want a propeller in your face.

The Convair B36 is one notable multi-engine aircraft with engines in pusher configuration, as is the Piaggio Avanti. And the Cessna Skymaster is a push/pull configuration (If you get a multi-engine rating in a Skymaster, your ticket will be limited to multi-engine aircraft with in-line thrust). Single engine aircraft are even more uncommon, and pretty much all I could find except the Lake Buccaneer are all kit-planes (e.g. Velocity, Rutan), ultralights (Quad City), military, or experimental.


texts: Does a strobe light shield act like a wingtip fence [or better sort of vortex generator]?

texts:
I was told it is a shield to avoid to blind the pilot during night flights when the strobes are on. Now, knowing the primary reason is, as far as I know, the above mentioned:

Does anyone know any official document where the definition of this device is mentioned?
Does anyone know any reference where the effect on the wing tip aerodynamic is studied? Considering different speed regimes?
Does anyone know if there are any regulations on this small device?

As far as I know, this device can be founds on the following aircraft:

King Air
T-6 Texan
Embraer Legacy 600

As can be seen, it can be found on models with and without wing tip devices.
One thing that should be mentioned on aircraft fitted with winglet (not wing fence at the tip as those found on the A380), is that during the pull up manoeuvre, at take off, a mild/severe separation is generally observed on the inboard part of the winglet. Could the strobe shield fitted in the Embraer Legacy 600 mitigates this by re-energising  the boundary layer. It would be easy considering the amount of cross flow at the tip.
Any official paper or informal discussion anywhere in the web would be very useful.
More pictures can be found on these links:
http://79ft.net/tag/mechanicing.html


texts: Tiger Airways Singapore's IATA code is TR while Tiger Airways Australia's one is TT, but the ICAO code for both is TGW. I thought that the ICAO codes are meant to be unique from one airline to another, not the other way around. Is this the only case?


texts:
My understanding is that Boeing 737-600/-700/-800/-900 are all 737NG.

I've read before that the previous generation (737 Classic) can't be used in the USA as they don't have fuel inerting systems.

But do all (or nearly all) 737NG have fuel inerting systems? I'm thinking here about 737NG worldwide, and not necessarily those in the USA.


texts: Could I issue clearances at a private airstrip without being a controller?

texts: Hypothetically, if I owned a private airstrip on my property, with all the necessary permissions to do so, and I only want certain aircraft landing there, would I be allowed to issue takeoff and landing clearances even though I am not an air traffic controller?


texts: How is an ILS approach conducted when following a heavy aircraft?

texts:
I'm following a much heavier aircraft on an ILS approach to a large airport.

Ideally I'd like to stay a bit above the glide path and land late, both to avoid the turbulence and also get off the runway quicker.

Is that actually a good idea, and how would I do that in IMC?


texts: Which pressure mode of operation has the most stress on aircraft frame

texts:
So I am want to know which mode of pressurization has the most demand on the airframe

Isobaric mode

constant - differential mode

unpressurized

I hope to get an answer because I have an exam and need to know
Thank you very much


texts: Why do many large turbofans have a gap (of turbine blades) between the LP turbine and HP turbine?

texts:
After browsing around a while, I noticed that many...I think almost all...large turbofans have this gap between the LP turbine and HP turbine. I took some screenshots and put a red circle around the gap.

Why do they have this gap? It's certainly not for the combustion chamber. That part comes before the LP turbine. The only thing I can think of is the LP and HP are on different spools so maybe they need some space for the bearings to brace the two shafts. But there should be bearings bracing the shaft all along its length so idk.

I'm guessing it would be more efficient to eliminate this gap and should allow a smooth transition from high pressure to low pressure. At the very least it would save some room at the end of the engine, shortening its length and maybe saving some weight.

EDIT: At first I thought it was totally empty. But it appears that space has stator vanes not shown in the pictures. I'm editing the title with the phrase "gap of turbine blades" because the original spirit of the question was about way there's a big space between the two sets of turbine blades. The space happens to have something else in it, but not turbine blades and I was wondering why those sets are separated.


texts: Can the V-22 carryout vertical takeoffs with shorter blades?

texts:
The V-22 has blades that are larger than blades on most helicopters. Could you make them smaller and still have the vertical takeoff effect?

Bonus: Does the V-22 get some of its thrust from the exhaust?


texts: Is there any reason to have ADS-B out that is not based on GPS?

texts:
The ADS-B system is only as accurate as the location data source it uses. In the US the 2020 ADS-B mandate requires that horizontal location data be from a GPS source with minimum performance standards set out in 14 CFR § 91.227.1

The aircraft in the Lamia crash in Colombia had ADS-B out that was based on an inertial system resulting in their ADS-B track being off from their actual position. It was off by 2 km when the flight began and drifted further during the flight, possibly being off by as much as 4 km by the time of the accident.2

Although ATC radar will still get an accurate location from the transponder, other aircraft might be using the data for traffic advisories through a system like ATAS. Using a system that could be sending inaccurate data has the potential to be dangerous.3 No info would be preferable to incorrect info. Is there any reason to install an ADS-B out system that does not use a GPS data source?

1ADS-B Frequently Asked Questions (FAQs)

2Satcom Guru: LMI2933 LAMIA AVRO RJ85 Medellín Deadstick

3At this point there is no reason to believe inaccuracy of location data had any bearing on the LMI2933 accident.


texts: What would the point to point range of the current Virgin Galactic Spaceship 2 launch system be?

texts:
Many people have suggested that the next step for Virgin Galactic after single point "space tourism" flights begin would be passenger suborbital flights, providing travel times many times faster than even the Concorde.

If they flew up to perhaps 30 miles, instead around 60 miles, much more of the rocket energy could be devoted to moving Spaceship 2 downrange.

If the Knight carrier aircraft flew straight towards the destination, how many miles would it travel before it reached the 50,000 foot drop altitude?

Then, on a flatter trajectory, how much further would Spaceship 2 go? How far could it glide after re-entry?

Not to rush things too much, but a "pilot scale" point to point flight from the Spaceport in New Mexico to California might be a good starting point.  Would it be possible?


texts: Is there any practical benefit of the Boeing-787 to perform near vertical takeoff?

texts:
In a promotional video for the Paris 2015 airshow, this video was released promoting the new Boeing 787's near vertical takeoff capability. Whilst highly impressive, I was wondering if there is any practical benefit or advantage of such an aircraft being able to perform this manouevre?
If there is no benefit of being able to climb at this angle of attack, then why was this aircraft designed with such a capability. But if the 787 wasn't designed to intentionally perform this, then does this mean other Boeing aircraft can do this? And if other aircraft can do this, then why hasn't this manouevre been marketed in such a way before?
In other words, why even bother to design an aircraft capable of this, if it serves no real benefit? And why market the aircraft as being able to do so in the first place?


texts: Do any regulatory bodies require ISO 9001 QMS certification from airlines or service providers?

texts: As the aviation industry is transitioning to SMS approach, is having ISO 9001 certification required from any civil aviation authority? Similar to how IATA requires IOSA certification and certain airline /  airport authorities require ISAGO certification for ground handling companies. Note this question is not trying to debate the advantages or disadvantages of ISO 9001 certification towards achieving safety, but rather the presence or non-presence in the regulatory landscape.


texts: Is there a recommended time to pause before transmitting, after changing to a new frequency?

texts:
Does any aviation authority have a recommendation of how long to listen after changing to a new frequency before making a transmission?

source


texts: Does a pilot have to request altitude changes when receiving flight following?

texts:
Let's say that during a VFR flight the pilot requests flight following from ATC, giving information about the aircraft type, type of equipment, destination and cruise altitude. ATC responds by giving a squawk and saying "maintain VFR".

In that scenario:

Does the pilot have to request an altitude change from ATC during flight following, even though the flight is under VFR?
Or, does he need to just advise ATC and start descending/climbing to another VFR altitude?
Or, is it not necessary to say anything to ATC about VFR altitude changes during flight following?

Finally, where can I find information about the regulations for flight following? I could not find anything in the FAR/AIM.


texts: Is there a V speed for the point an aircraft starts an ascent at 0 angle of attack?

texts: Some aircraft with an angle of incidence or cambered airfoils are capable of climb without any angle of attack, Is there a V speed for the speed at which an aircraft starts a positive climb?


texts: How can I find out if there's an EASA STC for something that has an FAA STC?

texts:
I want to purchase something for my Cessna from a US web shop.
The part has a Supplemental Type Certificate (STC) from the FAA, but I don't find any information about the EASA equivalent.

Is there any database to check this?


texts:
I'm trying to get a deep understanding of the term: Density Altitude.

So I have read the explanations in my instruction book, and online articles.
One source explained it differently then the other which confused me.

Wikipedia defines Density Altitude as:

  The density altitude is the altitude relative to standard atmospheric
  conditions at which the air density would be equal to the indicated
  air density at the place of observation. In other words, the density
  altitude is the air density given as a height above mean sea level..".

https://en.wikipedia.org/wiki/Density_altitude

So if I would believe Wikipedia then I could look at the ISA table to find the altitude by using the pressure.

Here is an ISA table:

My instruction book (Aerodynamica, prestatieleer en vliegtuigtechniek by Bas Vrijhof on page 112, written in Dutch) claims this:

  in de ISA is de dichtheidshoogte altijd gelijk aan de drukhoogte

Translated to English: in the ISA the density altitude is equal to the pressure altitude.

So, let's say I'm flying in an aircraft, the pressure is "22.22 Hg", and the outside air temperature is -0.9°C. The altitude in the ISA would be 8000 ft. The Density Altitude would also be 8000 ft.

Skybrary defines Density Altitude as:

  Density altitude is pressure altitude corrected for temperature.

Link: https://www.skybrary.aero/index.php/Density_Altitude

This explanation contradicts with the Wikipedia explanation:

  the air density would be equal to the indicated air density at the
  place of observation

On another wikipedia article I found this:

  De relatie tussen temperatuur, hoogte en luchtdichtheid kan worden
  uitgedrukt in density altitude.

Translated to English:
The relationship between temperature, altitude and air density can be represented as density altitude.
Link: https://nl.wikipedia.org/wiki/Opstijgen#Benodigde_snelheid

So in short, each source explains Density Altitude in their own manner, some contradict the other which confuse me.

So my question is:

What is Density Altitude?


texts: Why does intake of turbofan engine have angle of attack?

texts: As you can see the title of the question, intake of turbofan engine has an angle of attack. why? see:


texts: Why does a sharp leading edge result in a larger pressure peak?

texts:
I know in the real world the sharp leading edge (LE) will results in a larger pressure peak compared to a large radius LE.

And that there are three types of stall.

But I want the explanation in theory. I can't overcome the problem why the smaller the radius of the leading edge, the larger the pressure peak will be.


texts: Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years?

texts:
When Boeing introduced the 747-100 in 1969, its maximum ceiling was 45,100 feet; half a century later, when Boeing introduced the 777x, its maximum ceiling was 43,100 feet.

Similarly, the maximum ceiling of the Airbus A300, introduced in 1972, is 40,000 feet, while the ceiling of the A350, introduced 2 years ago, is 43,100 feet.

Given the all the other advances in aircraft design between the past and current generation of airliners, why has the ceiling remained unchanged?


texts: Is there any airline company owner who also works as a pilot?

texts: Do you know any airline company owner who holds ATPL licence and flies one of the company's aircraft occasionally in normal operations just because (s)he likes to do it?


texts: Do I need FAA permission to install tundra tires on a Piper PA-28 Cherokee 140?

texts: I do a lot of back county flying  and a lot of times the landing area is not in the best possible shape. I would like to install 29" tundra tires on it. Due to the change in wheel and tire size do I need to get FAA permission to make the modification and if so what would be the process?


texts:
Sailplanes capable of climbing in rising air (not troop transports, which can only descend after the towrope releases) have one or two seats.  I know of only one type with more, the Schweizer SGS 2-32 "2½ seater."  Even experimental one-offs like the Perlan series have at most two seats.
Ignoring social aspects such as marketing, class associations, and racing leagues, what are the technical difficulties in making/flying/maintaining a sailplane with more than two seats?  Frontal area, if seated abreast?  CG range, if seated fore-aft?  Something special about mass or wingspan that doesn't apply to powered airplanes?


texts: Where can I find standard aviation abbreviations for the "unit of measure"?

texts:
I have been in the aviation industry specialising in Logistics all my life.  There used to be a standard, the ATA 200, for how to abbreviate the unit of measures, such a EA for each, KG for kilograms, HU for hundred, and so on.  I understand that the ATA 200 is now dead and has been replaced by ATA Spec 2000 but I can not find these abbreviations in the Spec 2000.

I suppose that these abbreviations are still valid but where can I find them?


texts: Why are some aircraft's life limited by both cycles and flight hours?

texts:
For instance the Pilatus PC-12 life is either 27,000 cycles or 30,000 flight hours, whichever comes first.

I understand that the limit life in cycles is mainly due to fatigue in terms of pressurization/depressurization, but what about the maximum flight hours?

Imagine a world where the aircraft would fly only one flight of 30,000 flight hours, then there would be only one pressurization cycle, and one takeoff, so what limits the aircraft to fly more than 30,000 FH?


texts: To what extent is the HOST system still in use?

texts:
The Host Computer System (HOST) used to be the backbone of the US air traffic control centers (ARTCCs). There was a lot of publicity early in 2015 about the En-Route Automation Modernization (ERAM) fully replacing it, as the FAA announced they were finally finished implementing ERAM. However, deep in the FAA website, the HOST system still seems fairly active.

I just want to clarify if it is fully out now. Is it still available as a backup? Do certain ATC systems still draw from HOST systems? Do controllers still use certain HOST systems?

Overall this is a pretty technical question, but any information is helpful.


texts: Is there a standard for the frequency/interval between flashes of anti collision strobe light?

texts: As far as I've spotted on lots of aircraft, I've noticed that the anti collision flashes are in a similar interval, no matter if it's a Boeing 737, Airbus or an F-16 Fighting Falcon. Is there any international standard or any sort of aviation safety rules that standardizes the frequency of the anti collision strobe light? If there any such rules, does it regulate whether the lights should have a single or double flashes at a time?


texts: Does it really take 9000 feet to recover from a spin in a P-51 Mustang?

texts:
I was a bit surprised to hear from this P-51 pilot (9:33 into the video) that the Mustang requires 9000 feet to recover from a spin.  This seems high to me.  The Mustang POH does not confirm this, but given the indicated recovery procedure, it seems possible:

  b. RECOVERY. -- Recovery procedure is the same in both a left and right spin. Upon application of opposite rudder, the nose drops slightly and the spin speeds up rapidly for 1 1/4 turns, after which the spin stops. Rudder force is light at first, becomes very heavy for a period of about one second at the first half turn after starting recovery, then drops to zero as the spin stops. Recovery is effected in the normal manner, that is, by applying full opposite rudder followed by movement of the stick to neutral.

I've researched altitude loss in more modern GA single engine planes, and <= 1K per turn seems common.  See this discussion about altitude loss in a 77 Mooney M20J.

I've also researched altitude loss in the Mustang a bit further, but have been unable to find confirmation of this.  Now I don't imagine we have a plethora of Mustang pilots actively participating in this forum, so I'll temper my question to be, does 9000 feet seem reasonable?  If so, why?

Note: It is not my intention to call into question what the pilot in the video is saying.  He does admit he hasn't actually spun the mustang, implying he either read or heard this elsewhere.

Update, July 21st 2017

I came across this video, a VERY good 1944 briefing likely filmed for pilots who are being introduced to the P-51 (Have to admit, I never knew Lee J. Cobb was balding!) .  The pilot demonstrates both left and right spins starting at 20:58.  It is mentioned that it takes 3 turns to recover, but unfortunately, it is never mentioned how much altitude is lost.  However, I suppose it is possible that it could be estimated  by looking at the plane against the background by someone far better at this type of math than me.

I've also reached out to the Flight Chops guy to see if he or the pilot want to add their two cents to the discussion.


texts: What are the "parts" of a SID procedure?

texts:
In the ARINC 424 (downloadable from this link), the following information about SIDs procedures is given in the section 5.7 Route Type (RT TYPE):

As you can see, it appears to me that a procedure is formed by three parts. My questions are the following:

Is a SID made from 3 parts: Runway Transition, Common Route, Enroute Transition?
If yes, how are they related between one another? What is their order starting from the airport?
Could you provide an example from chart that shows these 3 parts?
Is there anything else i should consider in order to put together all the parts of a SID?

I hope my questions even make sense.


texts: Does pilot monitoring have authority to go around in exceptional circumstances?

texts:
Let's say the captain is acting as the pilot flying(PF) and the first officer the pilot monitoring(PM) in a commercial jet. They are shooting an ILS to their destination airport but the approach is so unstable that the first officer shouts "go around, go around" after passing minimum. But the captain ignores him and wouldn't balk the landing.

In this situation, does the first officer have the authority to take the controls from the captain by shouting "my controls" and go around? What about if their roles are switched? That is, what if the captain was the PM and the first officer the PF? Is the captain allowed to overide the first officer's decision to continue and initiate a go-around? I think this question can be better answered by commercial or airline pilots because I believe this is determined by company SOPs rather than FAR or ICAO rules. If so, are there any airlines that render the PM the authority to go around in defiance of the PF's decision under certain circumstances, like when the PM firmly believes the plane will very likely crash if an immediate balked landing is not initiated?


texts: How often are aircraft flown by two FO's?

texts: On Air France flight 447 the captain was on rest break and the a/c was being flown by two first officers. Most other instances I know of on long flights there is a relief crew of both a captain and an FO. How common is it to have two FO's and no captain in the cockpit?


texts:
The formula in Prouty's book shows

the blade inertia unit is slung-feet squared
rotor kinetic energy unit is foot-pounds

if blade's inertia is high, the rotor kinetic energy should be high.

In other words, blade inertia and rotor kinetic energy are two different terms for the same thing.

am I right?


texts:
Why do aircraft have two brake pedals instead of one?  If each pedal controls different sets of wheels e.g. the left wheels and the right wheels of the main gear, is that not a safety flaw given that at any point in time, it is impossible for the pilot to apply an equal amount of pressure to the brakes?

Isn't ABS enough to the point that only one pedal is enough?

Finally do both captain and pilot step on the brakes at landing? If not then why have two pedals?


texts: What is the reason aircraft are as long as they are wide?

texts: I've noticed most aircraft are as long as they are wide from nose to tail and from wing tip to wingtip, particularly private jets despite recent swept wing technology. You can almost draw a perfect circle with a compass if you could find the centre.  Is it for aesthetic purposes, principles of flight aerodynamics or any other reason.  Please explain


texts: Why is the F-16's service ceiling 50,000ft?

texts:
What defines the service ceiling for aircraft, in particular the F-16?

I suppose, as with almost everything, this depends on the aircraft, the engine type, etc. While I'm fine with a comprehensive answer including some discussions for different types of aircraft, I'm just limiting this to the F-16 to make it specific enough.

Basically, what exactly is it that prevents the F-16 from exceeding 50,000 ft?

Imagine an F-16 at 50,000 ft in a clean configuration, full afterburner, having reached around mach 2, then the aircraft attempts to climb at maximum rate of climb.

What will happen?

Is the engine unable to ingest enough air? Making the air fuel mixture too lean, eventually resulting in flameout or damage to the engine?

Is it due to the aircraft being unable to produce enough lift at this altitude? How much lift does an F-16 need anyway? Within a certain envelope, the thrust to weight ratio of the F-16 supposedly exceeds 1 and the aircraft can climb vertically -- however, I don't imagine this to hold true for very high altitudes, probably only within an narrow optimal set of parameters?

Is it a combination of the two? Which hits the F-16 first?


texts: How many people can stand on airliner's wings?

texts:
This photo of Allegiant Air flight 331 got me wondering: how much weight would a typical airliner's wings be able to hold?

Aside: Apparently these folks didn't realise that if they smell gas in the cabin, they probably shouldn't decide to go out of the emergency exits and stand ON TOP OF ITS TANKS! God forbid one of them gets nervous and lights a smoke!

My question is basically: how much weight are airliner wings required to hold $\div$ the average passenger weight? Theoretically how many people? :)


texts: Why do helicopter flights not appear in online flight trackers?

texts:
Currently in Indianapolis, IN (19 Mar 2015, ~08:00 EDT -4GMT), there is some sort of big kerfuffle downtown, and I can see 3 helicopters hovering over the near west-side of the downtown area. However, FlightRadar24 for the area doesn't seem to show them at all.

It's dim enough that I couldn't make out the markings on the choppers before I went inside, but at least one or two are local news stations, and the third is either another news station or a police chopper. They are in the (normal) flight path of Indianapolis International (KIND) runways 23L and 23R, though I'm sure they're below the approach altitudes.

Why are they not squawking something that would be picked up on either FlightRadar24, FlightAware or similar flight tracking web sites?

Update: It does appear that they're not using RWY 23 this morning, but are using RWY 5L and 5R.


texts: Does Flight Following automatically include permission to fly through class C or D airspace?

texts: The situation is as following - I requested flight following at approach, got a squawk and instructed to maintain VFR with heading and altitude at my discretion. My route is through class D and class C airspace for the altitude I chose. The question is - should I establish additional communications or report to the approach controller about flying through the class C and D airspace, or I am already permitted to do this?


texts: Can you fly an airplane at a 90° roll angle without losing altitude?

texts: I've seen this answer to the question about flying upside-down, but tilted by 90°, there should be no surface creating lift (except maybe the vertical stabilizer).


texts: What are the ACARS frequencies and what is their usage?

texts: I have been playing with a SDR dongle. I have been able to decode some ACARS signals using SDR# and acarsd. I have noticed in my area (35 miles west of DFW airport) there are a number of frequencies used. I have been able to decode transmissions on 130.450, 131.125, and 131.475. Are there other common frequencies? What determines the frequency used by a particular plane? I find it odd that I can pick up an AA flight 30 miles away and yet when a similar flight passes directly overhead, I am unable to find their ACARS on any of those frequencies.


texts: How much are aircraft nose paintings restricted by regulations?

texts:
It's actually surprising to see these old paintings on aircraft noses:

WW2 nose art, source

How much were (and are) these paintings generally restricted or allowed by law, civil regulation and military rules in countries like US, Russia, India, Australia (if the jurisdiction matters for a general answer)?


texts: Can a surrendered type certificate be reacquired by the manufacturer or by another entity, or is it considered to be permanently lost?

texts: On occasion, the holder of an aircraft type certificate or supplemental type certificate chooses to surrender it to its local civil aviation authority (for instance, the FAA or EASA), which has the effect of grounding all aircraft covered by the type certificate; can the former holder, or another person or entity, later reacquire the surrendered certificate, or is a surrendered type certificate permanently voided?


texts: Why are some airports not allowed as IFR alternates, even if conditions there are VFR?

texts:
Why are some airports disqualified for use as an alternate (as listed in a approach procedure for that airport (A N/A)), when there is a provision in part 91 that an airport without an instrument procedure can be used if descent from MDA and under basic VFR conditions are expected using the 1-2-3 rule?
Example: I19 (Greene Co. Airport near Dayton, OH) has a disqualification (A N/A) listed in the procedure. Yet 11 miles away, I73 (Moraine) has no procedures and as I know it there is no specific disqualification.  Albeit, you could only use Moraine for an alternate if descent from MDA and under basic VFR is forecast for the area.
So, why can you not use Green Co. if descent from MDA under basic VFR would be possible?


texts: Are there examples of taildragger autoland systems?

texts:
I have only been able to find examples of auto-land systems for tricycle gear. Is there an equivalent for taildraggers?

I realize taildraggers are more commonly used in VFR conditions, so there may not be a sufficient market draw solely based on the weather argument (as would be the case for e.g. commercial air transport). I also realize that taildragger aircraft tend to cost less, thus making it harder to justify investment in an avionics capability that would likely be expensive. But are there any other reasons why they are so much less common (if they exist at all)? The physics would be different, but modern control systems are capable of handling those...

Follow-Up Feb 23: Since there seem to be no obvious examples - and in light of the constraints identified above and in John K's answer - what would be the simplest (read: cheapest) taildragger auto-land system that would provide meaningful benefit (e.g. prevent ground loops)? For example, would a simple "Heading Hold Mode" augmentation system be helpful? If not, why not?

Fun Fact: The closest to a "landing system" that I could find is Brodie Landing System for the L-4, discussed here.


texts: Why EU/US airline checked baggage allowance limited at 32kg?

texts: For most full services on EU/US airlines, the permitted weight of each of the checked baggage allowance is 32kg. It is similar for the routes operated by non-EU/US airlines, even though their overall checked baggage allowance is more than that. What are the reasons behind that?


texts: To which side did the first Cierva autogyros fall?

texts:
The first Cierva autogyros, before the introduction of the flapping articulation, fell to the right when the take-off was attempted, according to witnesses. That had an explanation, as the rotor turned clockwise (seen from above) so that, when the aircraft moved forward at a certain speed, the right-side blades lost lift, the left-side blades gained lift, and the resultant torque rolled the autogyro to the right...
But, why didn't gyroscopic precession shift the reaction by 90º, pitching the nose up so that the machine fell backwards...?


texts: Was there a historical requirement to announce altitude, temperature, etc?

texts:
It is a common experience of flying on commercial flights that pilots announce certain flying conditions, including altitude and speed.

It has been previously asked on Aviation SE why pilots announce the cruising altitude of flights.  The answer there suggested there was "no real reason".

On Quora, it was asked similarly why pilots frequently announce altitude, outside temperature, and speed.  The first answer there suggested it was previously a historical requirement; however, the answer does not provide a reference to these requirements.

Has there been historically, or is there now, a requirement in any major jurisdiction (FAA, EASA, etc.) for the pilot (or flight crew) of a commercial flight to announce altitude, outside temperature, speed, wind, or weather conditions?  If so, what was/is the specific text of the requirement?


texts: What are the tube shaped structures on the back of the fuselage of this 737?

texts: A previous question asked what the little metal plates between the horizontal and vertical stabilizer were (they are vortex generators), however I am much more interested in what the gray tube shaped structures are that go down the top quarter of the fuselage. What are they and what do they do? Are they sensors, countermeasure pods, something else?


texts: Is the term "small" applied differently between piston engine planes and jet engine planes?

texts:
My understanding was that "small" covered planes up to 12,500 pounds, no matter the engine type.

Would that be gross weight/max takeoff weight?

Brought to mind by the two recent Cessna Citation crashes (Cessna 560, Cessna 680A), and head lines of "Small  jet crashed during takeoff"  and "Small jet crashed during landing". Pretty sure their gross weights, 15900 lbs and 30800 lbs would push them out of the small category.

Luckily, all crew and passengers were able to walk away in both accidents.


texts: Why is an aircraft carrier's arresting cable made from steel?

texts:
Steel seems to be what modern aircraft carrier arresting cables are made from.

It's strong, provides some elasticity, and serves its purpose well. However, it does need to be changed after every so many traps due to metal fatigue (about every 125 landings from what I've heard).

Why not use a more modern material such as Kevlar? Wouldn't a material such as Kevlar reduce the frequency which the cable must be changed? It's lighter, more flexible, more durable, can tolerate more temperature extremes, is not susceptible to corrosion, and it might even be cheaper - since it's made from nylon threads. It also has the added advantage of being less dangerous in the rare event of a cable break under load.

This BBC Documentary (no longer available) posed the same question, but didn't really provide any answer.

Why are modern aircraft carrier arresting cables still made from steel?


texts:
Is is possible for a flight simulator software to simulate the real time scenario of landing an aircraft on a water body. There are instances of this (Ethiopian Airlines Flight 961, US Airways Flight 1549) and the results were catastrophic/great  based on the type of water body they landed on and the situation which brought them there and several other parameters.

But I want to know if it is possible for a complex computer program to create this scenario effectively and thereby better equip the pilot ?


texts: Is flutter speed always smaller than divergence speed for aircraft?

texts:
In aeroelasticity, there are three main phenomena that one should take care of: divergence, aileron reversal and flutter. Each of them has an associated speed at which the phenomenon might start to occur.

During wind-tunnel tests it is possible to increase the flutter speed to have access to the divergence speed first by using some small masses smartly placed on the wing. This is due to the fact that usually flutter speed is smaller than divergence speed.

Is it always the case for aircraft (without additional masses on the wing)? If not do you have any example? If yes do you have an explanation why or a mathematical proof of it?


texts: Why do we see a reduction in temperature in a wind tunnel by increasing the velocity, but in a real flight it's the opposite?

texts:
In a real flight, when the speed of an aircraft increases, we see an increase in temperature too. So that at high Mach numbers the surfaces of the aircraft will be very hot.
Now I have encountered this issue that in a wind tunnel and for a test model it works in reverse order. So that the flow velocity in the tunnel is increased, the temperature of the test model surfaces will reduce, and at high Mach numbers, we need to use heaters to prevent freezing.

My question is this: is this fundamentally correct? If it is, what's the reason for this difference?


texts: Where to find general A320 E&E Compartment Information?

texts:
I'm student in electrical engineering and write my thesis on some topic of the e&e compartment. The main focus is on the computers of the A320 flightcraft, actually called E&E Compartment. Sadly because of closed source of this avionics part there is no general information of what it is. This is also clear why, most infos can only accessed by technician because of several security reasons. But maybe there is still some general descriptions and pictures that shows for example the location of e&e and text like: e&e has distributed system architecture where each computer has specific role, they are all connected by arinc... blabla.. and similiar and so on :)

It can be all, books, patents, googling keywords.. It would all help!

Thank you!


texts: What was the first supersonic wind tunnel?

texts:
What was the world's first supersonic wind tunnel? Who built it and how did it work?

All I've found so far is this Wikipedia article that says:

  By the end of the war, Germany had at least three different supersonic wind tunnels, with one capable of Mach 4.4 (heated) airflows.

The citation in the article is a dead link.


texts: What do these polygons mean on VFR charts?

texts:
There are a lot of blue polygons on this VFR chart:

What do they mean?
Source


texts: How to calculate minimum flying speed in distributed propulsion?

texts:
How to calculate minimum takeoff speed due to distributed propulsion?

Is there a quick way or rule of thumb way to calculate effects of distributed propulsion?

I understand NASA is doing research in this area and is determined to prove an increase in efficiency of 500% in real world tests, although this may include the benefits of electric distributed propulsion.

I understand they swapped the wings out on their Dornier, from 17psf to a 45psf wing loading.  That's an increase of almost 300% in just the aerodynamics!!

So....

I understand the bigger the prop disc, the more efficient the prop.

if I have a small ultralight with 25 hp, and now use two 12.5 hp motors instead with newly optimized props....

What is the approximate % increase in efficiency/thrust as the prop disc is now twice as big? ( assume only a small weight increase)

Now let's say I have a 10' span, with 2 motors with 6' props. The entire wing and tail is in the prop wash.

What is the formula for propeller exit speed(v2)?

Is this my new indicated airspeed(v+v2)?

In other words, if my stall speed is 40mph and my prop exit speed is 20 mph at zero ground speed distributed over the entire wing, can I take off at a 20mph ground speed? i.e IAS= 20mph ground speed + 20 mph prop exit speed= 40mph need for takeoff.

Is this correct, at least conceptually, after all, it's just like a headwind, no?


texts: Can airline pilots communicate with dispatchers?

texts: Is it possible for airline pilots to communicate with dispatchers? If so, what methods do they use? A special radio channel?


texts: How to select the most efficient airfoil for low speed flight?

texts:
What airfoil (or family) has the highest $C_L/C_D$ ratio at speeds in the $50\:km/h$ range.

The use case would be an ultralight with a max speed of $50\:km/h$


texts: How to get registration from ICAO 24 bit code?

texts:
The description of PlanePlotter claims that it can determine the registration letters from the ICAO 24 bit address algorithmically for some countries.

The only thing i got so far is how to get the country. Any clues?

Edit:

After some more research I found some information in the book "Principles of Avionics" by Albert Helfrick:

  Generally, there is no algorithm giving a one-to-one correspondence
  between ICAO 24 bit addresses and the registration number of the
  aircraft. Some ICAO member states did have an algorithm that would
  translate ICAO 24 bit aircraft addresses to registration numbers but
  ICAO strongly suggested the practice to stop.

Algorithm for swedish registrations: http://www.transportstyrelsen.se/publicdocuments/PDF165.pdf


texts: What are the "lumps" in the A380 flight-deck?

texts:
In this photograph of the Airbus A830 flight-deck there are two large "lumps" sticking up and out from the centre console, next to the engine thrust levers and flight-computer keypads:

I think they're just meant to be wrist-support for when pressing the keypad keys, but it seems odd to single-out that part of the flight-controls in particular for wrist-support. The lumps also seem rather tall to be used comfortably for extended periods (and I assume that's what the pull-out keyboards in the trays are for, so why bother having secondary keyboards down there in the first place?) - and it also hinders access to the 'inner' keys closer to the engine controls.


texts: What are typical naca foils for winglets for ultralights/LSA?

texts: What are typical naca foils for winglets for ultralights?


texts: Why are the cockpit windshields on the A350 black?

texts:
The newest planes like the 787 or A350 have a different kind of cockpit windshields:

Picture source

The A350 has "black" windshields:

Source

Does anybody know why are the windshields different?


texts: Is a vertical stabiliser needed for straight line flight in a glider?

texts:
My team is designing a glider and I am unsure about whether or not to include a vertical stabiliser. The task the glider must complete is to achieve the largest possible displacement in a straight line.

Our glider will not be able to automatically adjust the vertical stabiliser's position so it would stay upright and inline with the glider's fuselage for the duration of the flight. Since our glider does not require any changes in it's yaw angle (because it is flying in a straight line), I don't think there is a need for it.

Should we include a vertical stabiliser or not?


texts: What are the key differences between controlled and uncontrolled airspace under the FAA jurisdiction?

texts: The FAA utilizes the ICAO definitions for class A-E airspace as controlled and class G as uncontrolled (class F airspace is unused under the FAA). What are the key differences between controlled and uncontrolled airspace in general?


texts:
When I start editing a flight plan in Garmin Pilot, if I have a distance that is farther (like 1,000 nm or farther) I get these two symbols in the map on the Flight Plan pane:

One is a tower and the other is an oval.

Here is the entire pane view:

Any idea what these two symbols are?

The tower looks like the same symbols as 'obstruction' from the Garmin Pilot manual, but note that the filed altitude is 39,000 feet (ie, no obstacles that high around here.)

What about the little oval?


texts: Do test pilots on commercial aircraft wear a parachute?

texts: I was watching a video of the first A350 flight. At 0:35 one of the pilots appears to be wearing a helmet and what looks like a parachute. Is that true? Do pilots on maiden flights wear such a kit, so that in case of an emergency they can evacuate the airplane?


texts: Why is Cessna 172 POH performance chart based on Pressure Altitude and Temperature instead of Density Altitude?

texts:
While calculating takeoff distance for Cessna 172, POH need to be used. POH charts has pressure altitude and temperature and then distance for those two known parameters.

Does this mean if we have pressure altitude and temperature then we don't have to worry about density altitude in our calculation? Why would we want to calculate density altitude if we only need to know pressure altitude and temperature?


texts: What are the considerations for coding the GPS before engine start without external power?

texts:
Suppose I would need 10-15 minutes to fully configure my G1000 on a C172 ahead of a flight, with the flight plan, my personal view settings, etc., and prefer to do that before starting the engine. My goal is to save fuel, save hobbs/tach time, and reduce deposits accumulating on the spark plugs.

What would be the considerations against doing that on battery power alone? And what can I do to reduce the impact of any downsides?


texts: How is the crew rest area on the A350 accessed?

texts:
As per this image of the A350, the crew rest areas have been placed on the top of the fuselage. How can this be possible and how would the crew get into the rear one since it seems that it is placed above first class?

I understand that the front one is accessible from the cockpit, but the second one seems to be straight on top the first/business class section. Is this actually practical?


texts: What is the difference between Boeing 777-31H and Boeing 777-31H(ER)?

texts: What exactly is the difference between a B777-31H and B777-31H(ER)? Is ER the latest version of 777-31H?


texts: Why do passenger embark on the left side of an aircraft?

texts:
I speak of passenger aircraft that can be found on large airports.
The left side is used by passengers (and the crew) to embark/disembark (see the position of jet bridges) and the other side to embark/disembark the rest (e.g. food).

Why do we always use the left side for passengers? What prevents an airport from deciding to use the other side?

If this is an historical decision (e.g. one day in the past an aircraft builder decided passenger should use the left side, then majors airports were built accordingly and thus new aircraft were built accordingly and thus new airports were built accordingly), is it possible and reasonnable to build a jet bridge made to operate on the right side of an aircraft and then use the right side for passengers and the left side for the rest?


texts: Have there ever been accidents due to a vacuum failure that hasn't been noticed?

texts:
When the vacuum system fails, the artificial horizon slowly goes back into it's non-vacuumed position. I found no picture on that but it's a quite high angle of bank that is indicated.

Has there ever been an accident because of the failure of the vacuum system? In flightsim, I always needed some time to realize the AH is no more working and adjusted my bank to "fly straight" again.


texts: Are jet aircraft still at risk of hijacking by people wielding melee weapons?

texts:
Are jet aircraft still at risk of hijacking by people wielding melee weapons (as opposed to explosives)?

I thought that aircraft were designed post-9/11 such that passengers can't enter the cockpit, but Wikipedia's list of hijackings mentions incidents this decade which involved melee weapons:

  China June 29, 2012: an attempt was made to hijack Tianjin Airlines
  Flight GS7554 from Hotan to Ürümqi. Six people tried to hijack the
  aircraft 10 minutes after take-off. There were 6 police officers on
  board. Four were in plain clothes, taking the plane for a business
  trip. The hijackers used aluminium canes with sharpened tips to attack
  the members of the crew. The police officers and civilians on board
  subdued the hijackers, all of whom were of Uyghur ethnicity. The plot
  was foiled and the plane returned to Hotan in 22 minutes after
  takeoff.


texts: As a supplement to this SE question; "What are the requirements to become a language proficiency examiner?" (something I never heard of...) What are  ICAO English language requirements?


texts: Can an LLC formed solely to own and operate an aircraft be operated under Part 91?

texts: A non-pilot purchases an aircraft and puts it into an LLC. Then non-pilot hires pilots, places insurances, rents a hangar and pays for all other costs and expenses with the sole purpose to fly the his family on personal trips and vacations (no business purpose), can the aircraft still be operated under Part 91? Or, because the non-pilot who owns the LLC is providing funding for the operation of the aircraft, does this constitute operations under Part 135?