texts: How many aircraft and pilots can a part 135 cover?

texts: If you form an LLC for charter flights, can you hire an unlimited number of pilots to fly under the same part 135 certificate (assuming all are commercial pilots), or does each pilot and/or each aircraft (all aircraft owned by the LLC) need to have their own part 135 certificate?


texts: Are commercial pilots ranked or graded differently based on the size of the aircraft they fly?

texts:
I am not sure whether "rank" or "grade" are the most suitable words for this question. If someone know which the most suitable, please edit this question.

I mean, is the rank of a pilot of, say a Boeing 737, different than the rank of a Boeing 747? And the equivalent to my pilot of Airbus A320 and the pilot Airbus A380 are ranked differently? If different, which one is higher?

This question is related to the airplane's passenger capacity, not to the most advance technology installed in one particular airplane.


texts: What are the criteria for conceptual design of thrust reverser in the use of braking?

texts:
I'm doing a project: Study of aircraft braking and pre-sizing of associated subsystems. We tried to find criteria for the reverser in the braking phase. I read FAR 25, but I did not find it.
Is there a criterion such as how many percent of the braking force must be applied by the reverser in certification documents?


texts: When extreme yoke movement cuts out stab trim on a 737-NG, does it stay off after yoke returns from limits?

texts:
I've read that the 737-NG has logic built into the stab trim system that will cause stab trim to cut out if the control column (yoke) is pulled/pushed far/hard enough (it's not clear to me if it's travel distance or force thsf causes the cut out).

My question is, given the control column stab trim cutout mentioned above, does it continue to function after the control column is moved back from its hard stops or force is decreased  below a certain value?


texts: Why are aircraft not equipped with nose cargo doors when being converted from passenger to cargo variant?

texts:
I'm trying to find any substantiation / design justification why none of the OEM/STC holders are able to provision nose cargo doors on A321 / B757 / B767 / B777 fleet as part of P2F (passenger to freighter) conversions.
I'm sure there would have some discussions/presentations on this, appreciated to guide with reference.


texts: Where can I find data tables for lift and drag coefficients of airliners?

texts:
I'm teaching an introductory course in fluid dynamics and I'd like to show some "real" data regarding drag and lift forces on an airfoil. It is easy to find data on the geometry of typical airfoils, but I was not so lucky with $C_L = f(airfoil, Re, i)$ and $C_D = f(airfoil, Re, i)$ ($Re$ is the Reynolds number and $i$ the angle of attack). I'm looking for that kind of diagram or data :

Data for commonly known aircraft would be great (B737, B747, A320, A380).

Thanks.


texts: What is the rotor speed of an EC135/H135 helicopter?

texts: I need the Eurocopter EC135's rotor speed to estimate its natural frequencies. I checked the helicopter TCDS but I only find there percentage values. For example for the P1 variant: 104% Max and 95% Min. This is percentage of what? In other helicopters I normally get concrete values in RPM.


texts: Are all US fighter/combat aircraft constantly armed, even just in training?

texts:
I remember hearing once upon a time that all US fighter/combat aircraft constantly armed, even just in training. If I recall correctly, it's because the pilots need to be ready at a moment's notice.

Is this true?


texts:
Why does automatic trim exist only in the pitch axis? For example, a flight computer can hold the current pitch automatically when engine thrust is applied.

Why automatic trim not lies in roll and yaw axis?


texts: Performance Calculation with upgraded engine

texts: I have an upcoming checkride and the DPE has asked to plan a cross country flight.  The aircraft that will be used is a PA28-151; however, it has an upgraded 160hp engine.  Regarding performance calculations, should I use charts from the current -151 PoH or can I use a charts from a similar model -161 PoH?


texts: Why is C-5 Galaxy not used for commercial airlines while Boeng 747 is?

texts: For a layman like I am, both the planes look massive and similar in size and shape, as if a near copy of each other. Do the similarity only end in the size and shape? Do they not perform equally well in similar roles? While Boeing 747 is used for commercial airlines, why isn't Lockheed C-5 Galaxy? Similarly, why is C-5 galaxy popular for Military and 747 isn't?


texts:
Following on from this question on the descent rate formula.

It appears from the answers and comments that a 3 degree slope is pretty standard across the board.

I would like to know why a 3 degree descent rate is used? I thought it would vary based upon the scenario.


texts: What exactly is the purpose of a pilot keeping a logbook?

texts: More specifically: in Canada what are reasons and protocols of keeping a logbook?


texts: What is this "string" in front of canopy of F-14

texts:
I was just watching scenes from Final Countdown movie and this little stringy bit caught my attention. Anyone knows what it is and what is its purpose?

Here is the video I saw it in.


texts: Which "pilotless aircraft" did the authors of the 1944 Chicago convention have in mind?

texts:
The Convention on International Civil Aviation (a.k.a. the "Chicago convention"), includes right from its first version, signed in 1944, an article about "pilotless aircraft". The article in question reads:

Pilotless aircraft
Article 8
No aircraft capable of being flown without a pilot shall be flown
without a pilot over the territory of a contracting State without
special authorization by that State and in accordance with the terms
of such authorization. Each contracting State undertakes to insure
that the flight of such aircraft without a pilot in regions open to
civil aircraft shall be so controlled as to obviate danger to civil
aircraft.

The original text is available here.
I would guess that language like that (which it takes time and effort to produce) will not get included in an international treaty without a reason.
So the question is, which aircraft did the authors of article 8 have in mind in 1944?


texts: Why are airplanes riveted and not screwed?

texts: Replacing airframe panels and inspecting hard-to-reach parts would be easier with screws, I presume. So why are rivets used?


texts: Could the principle of owls' silent flight be used for stealth aircraft?

texts: I was wondering about the ability of owls to fly so silently. Is it because they flap gently, they flap less often or do is their structure responsible? I was thinking their principle of stalking can be applied to stealth aircraft. Is it possible?


texts: Are there any planes that have ramjet or scramjet engines? If so, how did they reach the required mach speed for the engines to start functioning?


texts: Why isn't the Presidential 747 "Air Force One Heavy"?

texts:
Aircraft with a maximum takeoff weight of at least 300,000 pounds add the word "Heavy" to their callsign.  (Example: Lufthansa 415 Heavy in this video.) The current Presidential 747's have a maximum takeoff weight of 833,000 pounds.  Yet, it flies (when the President is on board) with the callsign "Air Force One", not "Air Force One Heavy."

Why not?


texts: From Aerodynamic view, what is the advantage/disadvantage of the Akagi Kaman K-Max Helicopter?

texts:
Here is a video showing the helicopter, the rotors are perfectly synchronized.

As there are not many such design helicopter, then my question are, is any aerodynamic weakness? What is its advantage/disadvantage of that helicopter?


texts:
I've been reading some articles online about flying wings aircraft design. But articles about box wing design (of similar depth to flying wing articles) seem harder to find.

For illustration, here are two example aircraft, one of each design, i.e. flying wing and box wing respectively.

Northrop YB-35

Sunny box wing aircraft

From the two images above, I can easily figure out a similarity and a difference between the two aircraft: The swept wing and the vertical stabilizer

What are the major similarities and differences between the two aircraft configurations? For example, if the sunny box wing aircraft doesn't have a swept upper wing, will it still be stable in flight, and is wing sweep necessary for flying wings and box wing aircraft?


texts: What is the dutch roll filter? How does it work?

texts:
Some airplanes have a dutch roll filter for the "yaw damper."

What is the dutch roll filter?
When is it used?
Is it ever required for certification or operation?
How does it work?


texts: Pros and cons of a pull-push propeller configuration

texts: What are the pros and cons of a pull push propeller in comparison to a counter rotating propeller?


texts: Are there common standards for aviation graphical user interfaces?

texts:
I'm searching for graphical user interface in aviation guidelines.
Yet I miss the correct terms and I don't really know where to start.

Let's take an example:

what's the meaning of the green color?
what's the meaning of the pink color?
is the color code regulated?
is this look (color, fonts, layout) regulated globally or does this vary by airplane type?
…

I guess that's a bit of a naive question but I gotta start somewhere.

A bit more Background: I'm a graphic designer. I have to create a web-interface for a national air rescue service. They want the look and feel to be as aviation specific as possible. The web app won't be used in the airplane itself so it is not regulated and it provides non-critical services.

One thing is that the interface should look cool and "techy". But on the other hand I don't want to use colors or layouts which are either very regulated or have a highly specific meaning.


texts: How do I know which airspace requires what RNP value? More specifically, can I go from NY to London with just BRNAV providing I stay above the NAT HLA?


texts: When were civilian aircraft first directed between aerodromes by air traffic control?

texts:
I feel fairly certain that when the Wright brothers flew, they did not need to contact air traffic control for clearances.

These days, it isn't uncommon for the entirety of a flight to be under ATC control, from before leaving the departure gate to after landing. Even flights in uncontrolled airspace can make use of services provided by ATC.

Ignoring early departure and late approach and landing, and instead focusing on the en-route or cruise part of flight, when was the first time civilian aircraft were directed or guided from one aerodrome to another by air traffic control (or perhaps rather, what would later evolve into modern ATC; I doubt it was called "air traffic control" at the time) in a manner similar to today's? Where in the world did this take place?


texts: Should the weight of the lifting surfaces be deducted from the weight used to calculate the C of G of the aircraft?

texts:
If the aerofoils are creating lift they are doing the work to lift the helicopter.  When the helicopter is hovering, the blades are carrying the weight of the entire ship. The forces on the aerofoils are acting in the opposite direction to gravity which is pulling the ship down. These opposing forces create a situation where the ship is now hanging from the aerofoils.

So would this mean that the weight and balance calculation for the pilot should not include the weight of the aerofoils as this weight difference would affect the C of G?

A fixed wing aircraft would suffer the same results?

My question is, should the weight of the section of the aerofoils of an aircraft  that provide lift be deducted from the weight used to calculate the C of G of the aircraft?


texts: Can ATC separate IFR traffic in class A airspace from VFR traffic in class E?

texts: Is it possible for ATC to apply 3 miles separation between an IFR aircraft in class A and a VFR aircraft operating in class E, just below class A?


texts: Can I document a VOR check with a photo to comply with 91.171(d)?

texts:
I'm interested in understanding the limits of what it means to "sign" a record. While enroute for any meaningful length of time, I try to tune two VOR's and I take a photo of the G1000 NXi on my phone to ensure I always have a current VOR check. This photo contains metadata with the date and place the photo was taken, and the photo details the bearing error. The only thing i'm missing for this photo the be the "other document" I require and to avoid having to write out a random slip of paper to that will satisfy the requirements for 91.171(d) is the signature.
I understand this signature is to certify that this information is factual and that it really took place and that the legal definition of a signature has evolved a lot over the past few decades. Clearly it doesn't matter that I infer the intent of the signature portion of the rule to be to ensure that no one lies about performing the VOR test.

Is my photo sufficient because it shows that the test was actually performed?
Should I edit my photo and scribble a "signature" on it?
Maybe a live photo with a "voice signature" would work?
Or do I need to keep writing on little scraps of paper to cover myself?


texts: Can a convergent nozzle be used for a supersonic jet engine?

texts: Can a supersonic fighter incorporate a convergent nozzle or does it always have to be a convergent-divergent nozzle?


texts: What would be the general steps for making a flight in a biplane?

texts:
I'm a writer, the story I'm writing is set in 1942. It's an alternate history of sorts, so there's no pesky WW2 to worry about, but technology has developed in roughly the same way. As part of an action sequence, my character, Scarlet, is going to steal a biplane to escape pursuit. She has a pilot's license and knows how to fly, but until this point, she hasn't needed to actually show her stuff.

What I do need to know, in layman's terms, are the general procedures of how the flight would go, any preparation that might be needed, and approximate speeds.


texts: Can cameras and LCD screens replace cabin windows?

texts: Windows in aircraft create a weakness to the structure, that is why they are very small. I'm not asking about installing them in the cockpit, which would create safety pitfalls, but could the windows in the rest of the fuselage be replaced by cameras and LCD screens that provide real time images of the outside world that even passengers sitting in the middle of wide bodied aircraft can enjoy?  This could even include a sky camera for night travel.


texts:
GNSS Horizontal Integrity Limit/ Horizontal Protection Level is a measure of GNSS position error/integrity that's very important in RNP operations and RAIM, but it has an obtuse definition in aviation regulations like DO-229D that's hard to apply in practice:

  [HPL] describes the region assured to contain the indicated horizontal position. It is a horizontal region where the missed alert and false alert requirements are met for the chosen set of satellites when autonomous fault detection is used.

Is there a simpler definition that is equivalent for most equipment? It seems like a 1 - 10-X% accuracy bound, given pessimistic assumptions about satellite availability, but given the description it's hard to be sure?


texts: What variables is an engine's AFR based on?

texts:
Maybe this is a bit too technical for an aviation forum, but it specifically concerns a flight engine.(Rotax 912 iS) Road vehicle engines will probably have different behavior. As you may know, the 912iS is a fuel injected engine where you can't manually control the mixture.

I have logged some data on a dyno bench, and i can clearly see a relation between RPM and Air Fuel Ratio. The higher the rpm, the leaner the mixture.
Strangely enough, throttle position or MAP value has no clear relation with the AFR, much unlike a car's engine. I thought i'd ask here since you guys may know what variables a flight engine uses to determine the AFR it wants to maintain.

My guess is that the following variables influence the AFR, but i don't know how and how much:
-Throttle (with exception of WOT or near WOT, which causes rich mixture)
-MAP (i'd guess higher MAP makes for a richer mixture, but not)
-Temperature of intake air, and exhaust gas etc.
-Temperature of oil, coolant etc. (i'd guess a richer AFR is maintained during startup=low temps)
-Known volumetric efficiency at certain circumstances

Finally, are there other factors affecting the AFR, like angular motion of the throttle valve? With carbs used in cars you always had an acceleration pump or a damper in case of a constant depression carb.
This is for the engine to attain the desired rpm/speed more rapidly.

Thanks for the help, cheers.
i'd like to hear if there's other forums more focused on technical aspects of flight.


texts: Can aircraft depart/arrive after another aircraft has sprayed snow on the runway?

texts:
Does snow spray affect runway surface friction? The weather was bitterly cold on March 18th, 2018 and Birmingham airport was covered with snow. As you can see in this video, an A380 sprays snow on the runway when arriving and departing.

(Frame from video)


texts: How to programmatically access AIP data, METAR, TAF, NOTAMs?

texts:
I'm looking at developing an app where one of the functions I would like to implement needs to use data which is normally available in AIP, like:

Aerodrome names, ICAO codes, GPS location, elevation
VFR reporting point names, GPS location
Nav points (names, locations)

In addition, I may want to display or use data from NOTAMs, METARs, TAFs, etc in my app.

Does anyone know the official sources for this data, ideally published by CAAs (FAA in the US, Eurocontrol in the EU and similar)? Please note I'm really only interested in programmatic access (e.g. a JSON, XML or similar feed available through a web API or similar), as opposed to document based data in the form of PDF or HTML files.

It goes without saying that I would ideally like this access for free, but a commercial arrangement is also I would look at - provided it's not outrageously expensive.


texts: On ATC's radar, does an aircraft that loses its transponder simply disappear?

texts:
If you look at shows like Air Crash Investigation, which surely take some creative license in how events are portrayed, they often portray the disappearance of an aircraft, or specifically loss of its transponder return, as the radar return simply disappearing from ATC's radar scopes.

My question is: is that actually the only thing that happens when ATC secondary radar loses an aircraft's transponder return, when the aircraft is not actually on approach to land (and thus losing line of sight to the radar would be normal and expected, and/or that radar return is no longer relevant for air traffic control purposes)?

In general, humans are better at picking out things that are there than they are at picking out things that aren't there, even if they were there previously. It's also very rare for an aircraft to lose its transponder, let alone crash. Therefore, some kind of positive notification that a transponder return was lost when it shouldn't have been, possibly after a short delay (to account for those aircraft where the transponder is set to standby while a new code is being selected) would seem helpful.

Yes, it's the controller's job to keep track of the aircraft they are in charge of, but especially with modern, digital radar systems, it seems like something like flashing a distinct symbol where the aircraft was last seen, or sounding an alert chime, or just about anything, could make their job a lot easier the very few times that an aircraft transponder return disappears when it shouldn't have.


texts: Why does the Cessna 172S Skyhawk use only two blade fixed pitched prop?

texts: Surely it would get more thrust from a three blade variable pitch propeller. From what I've read it's all about the area swept and also should be far enough apart to not cause too much interference. Besides having a constant speed prop would allow for a wider range of optimum operation.


texts: What would be the effect of skinning over the gap in fixed leading-edge slats?

texts:
The Zenith STOL CH-750 experimental aircraft uses a modified NACA 650-18 airfoil (having a 17% fatter-than-normal thickness) with a fixed leading-edge slat.   In an effort to reduce drag and improve cruise performance, some of the builders remove the leading-edge slats.  Instead of removing the slats, I am curious what the effect would be if one left the slats in place, skinned over the slots with a removable leading edge (shown in red dotted line), and added vortex generators.

How would this modification affect the center of gravity for the aircraft?

Would this modification affect the chord length?

What are the pros and cons of such an experimental modification?


texts: How is the due date for landing gear replacement determined?

texts:
I want to know how calculate the due date of Boeing MD-83 Landing gear replacement (it is every 10 year or 20000 FC).

Is it calculated from the installed date or shop visit date?


texts: I see YouTube pilots do it all the time, but I’m wondering how safe this maneuver really is given the fuel is a gravity fed system. Also, is it legal?


texts: Why does a Thrust Vector Control System increase maneuverability?

texts: So why can a thrust vector control system increase my maximum g-load capacity? Because still n=L/G is relevant and if I can not provide enough lift (pointing up) to counter balance the thrust (pointing down to spin a missile around c.g.), why should I use it?


texts:
A new TFR was recently published, which references the Riverside (RIS) VOR/DME.

When I look at the relevant chart in SkyVector, I don't see such a VOR in that area.

When I put the ID "RIS" into SkyVector, it takes me to an intersection outside London, UK.

PilotNav has the info, but that took a lot of searching.

How is one meant to interpret this TFR if the nav aid is so hard to find?
Why didn't they use bigger and easier NavAids like MCI or ANX, which are not far away, and clearly depicted on the charts?

Update!After I brought this to the attention of the local offices, they canceled the TFR and issued a new one expressed in terms of the MCI VOR, which makes a lot more sense.    The FAA was incredibly responsive and helpful!


texts: What are the advantages and disadvantages of have the wing positioned further aft on an airplane?

texts:
I've noticed that there is some variation in the location of the wing on airliners: The Boeing 737 has its wing mounted near the midpoint of the fuselage:

while other aircraft like the CRJ or the Airbus concept plane shown below have the wing mounted further aft.

What are the advantages or disadvantages to these wing locations, and why might a designer pick one over the other.


texts: What is the procedure for a rejected Jet/Rocket Assisted Takeoff (J/RATO)?

texts:
Seeing the image of a Lockhead LC-130 doing a jet assisted takeoff in snow mentioned in this answer, I wonder:

What is the procedure for a rejected takeoff when using JATO?
Can the JATO rockets be turned off once ignited?

(Image source:  Wikimedia Commons)


texts: What is the FAA's official stance on logging illegal flight time?

texts:
To preface my question, I want to discuss the reality that with the number of people and flight operations, there are surely cases where pilots have mistakenly flown under conditions in which it is not legal to do so.

Possible examples:

Students soloing after endorsement expiration.
Pilots flying without realizing their medical has expired.
Non-instrument-rated pilots inadvertently flying into IMC.
Carrying passengers without landing currency.
Acting as PIC beyond BFR currency.

Barring any discussion or speculation about punitive actions for the above listed items, what would the FAA's stance be on logged time?  Would it be logged as valid pilot time regardless of it being illegal, or does the fact that it is illegal make it null and void as logged pilot time?

For example, in the first scenario, if a student solos without a current endorsement, would it be able to be logged as PIC solo or would it not exist in the eyes of the FAA as it pertains to flight time and the flight would be considered to have been performed with a complete lack of an acting PIC?


texts: Who can request a check on an engine before boarding/takeoff?

texts:
I have read on a newspage that a passenger found an engine problem on the B767 before takeoff and requested staff to check it, while the airport claims the decision was made by the pilot.

I was wondering: Who has the right to do such decision. Will the engineers check the engine just because of a passenger's complaint?


texts: Are any special certs or licenses needed for Snow-ski equipped planes?

texts:
It has been asked and answered here that the ASEL is for Land operations and ASES for Seaborne. Are there requirements specific to using snow-ski equipped planes?

I am most interested in the US, although discussions of other places is fine.


texts: Induced drag - inverse proportion between induced drag and parasitic drag

texts:
I recently learned that the slower an aircraft is traveling, the higher the induced drag and the lower the parasitic drag. The parasitic drag is lower because the particles have less force against the aircraft (all types of parasite drag: form, skinfriction, interference, and ram). However, why is induced drag higher?

From what I understand, I thought that it would be low as well, because if the aircraft is moving slower that would mean that the air pressure would be less on the bottom of the planform, meaning the vortex created at the tip of the wing would be smaller (smaller difference between pressures) thus having less induced drag.

Can someone help explain to me why it is inversely proportional as such?


texts: Why does the FMC in B737 limit the climb speed to 230 knots on the VNAV mode until the leading edge devices are fully retracted?

texts:
In the VNAN climb on B737, the FMC changes the target speed from V2+20kt at liftoff, to 230kt for acceleration at the preset accleration height, then to 250kt (below 10,000ft) as the leading edge devices are fully retracted along with the trailing edge flaps.

My question is: Why is the climb speed limited to 230kt on the VNAV mode until the leading edge devices are fully retracted, when there are only operating speed limits to trailing edge flaps as below?

For your information, I've found a discussion on this topic on another aviation website but no one seems to have a definite answer to this.

https://www.pprune.org/tech-log/570676-737ng-led-s-speed-limitations-ops.html

Does anybody have a good answer to this?


texts: What has Airbus done to address the dual input issue?

texts:
There have been a couple of fatal incidents involving Airbus aircraft, namely Indonesia AirAsia Flight 8501 and Air France Flight 447, that could have been prevented had the captains orders / input been the only accepted one. In both cases the captain was commanding push down to recover from a stall, while the FO was pulling up. Because of the dual-input system they cancelled each-other out and the stalls were not recovered from.

Has Airbus done anything to address this? It seems to me that if the aircraft is in alternate law, as it was in both cases, perhaps it should only accept input from the left seat.


texts: What is the type of the seaplane at the end of runway 18L on Schiphol Airport?

texts: From 47 to 52 seconds into this video we can see a seaplane parked in a small pool of water. What type of plane is this and when did the plane fly for the last time?


texts: Is Autopilot engaged when an engine failure above V1 occurs on modern airliners?

texts:
If you lose one engine during takeoff in a multi-engine aircraft, you're trained to follow a standard emergency procedure: Pitch for Vy, use bank and rudder for zero side slip, mixture full rich, props full forward, power full forward, gear and flaps up, and then run an emergency checklist for one engine failure.

When one engine failure happens in a modern jetliner, what do the pilots do? Do they engage the autopilot right away so that the computer can take care of pitch, bank, and rudder for the best performance for a single engine operation? Or do they basically follow the same procedure as the one written above, which is used by GA multi-engine pilots?


texts: Can a supersonic plane use a subsonic wing if the nosecone shock produces subsonic airflow around the wing?

texts:
A supersonic plane will produce shock waves off the nose cone, as seen below:

These oblique shocks reduce the speed of the air that the wing experiences. If the plane is at a low enough Mach number, the shocks will reduce the speed of the air to below Mach 1. For example, I calculate (with the Taylor-Maccoll equations, I could be wrong) that a Mach 1.5 plane with a nose cone total angle of 25° will produce Mach 0.7 flow following that shock wave.

Assuming the shocks off the body don't significantly alter the Mach number, the wings will experience this lower Mach number if their span isn't too large. The wings are then experiencing a Mach number lower than most commercial jets.

Why, then, do almost all supersonic planes use either a highly swept leading edge (most jet fighters) or a sharp leading edge (like the F-104)?


texts: What are the historical precedents of today's E2 and E4 airspace? (US)

texts: What are the historical precedents of today's E2 and E4 airspace?  From what previous airspace classes did these airspaces evolve?  How do these precedents help us understand the significance of the distinction between E2 and E4 airspace today?


texts: Can a helicopter fly without a tail rotor?

texts: Just wondering if a helicopter can fly without a tail rotor?


texts: Can an engine on a Boeing 737 fly just using compressed air instead of jet fuel?

texts: I was just curious because the air is very compressed in the engine and some things do run on compressed air. And what if the engine was powered all by electricity?


texts: What is the meaning of T/O Thrust => TRQ / N1 in a flight log?

texts:
I work at a software company which builds record-keeping software for aviation.

What is the meaning of TRQ / N1 in a flight log, under a T/O Thrust header? I imagine it refers to torque at N1 (but in my limited experience, I have rarely encountered instantaneous torque as a relevant measure in aviation so I'm suspicious).

What is the meaning of TRQ / N1? Is this, like N1, expressed as a percentage?

(Indeed, we have a close relationship with out clients and can ask them, but answers sometimes take time and I prefer to be proactive and know more than the bare minimum.)


texts: Why was there no thrust from the engines in the TACA Flight 110 incident?

texts:
I have just watched Mayday episode 11, season 11, "Nowhere to Land" about TACA Flight 110 incident. Most key issues of the incident are clearly explained in the episode:

Why both engines turned itself off,
Why there was an overheating alert after restarting the engines (and they had to be shut off).

But, there was a short period of time between restarting the engines and manually shutting them off when pilots were claiming that (based on instruments) both engines are working (spinning), but there is no power / thrust being generated by them (i.e. plane has no power).

Either I missed something or this small issue was not explained.

What does it mean that engines are working (spinning?), but not generating any power? Does this refer to situations where only compressor fans are spinning in the cold section, but there is no fuel burnout in engine's hot section? Or is it something else?

And what can cause such situation? If I am not mistaken or not missing anything -- episode explains issues with heavy rain and hail that damaged fans, but says nothing about fuel distribution system, engine ignition or any other issue that could cause spinning engine to not generate any thrust.


texts: How much is airspeed reduced on an A10-Warthog when firing its cannon?

texts:
I just read on reddit that you could use the recoil of the gun as the propelling force for the A-10 if pointed backwards. There is also a question here on Aviation.SE, saying that the gun has the same power as one single engine.

I'm now wondering how fast airspeed actually decreases when firing the gun.

Let's suppose the aircraft is in level flight with no acceleration in any direction. The gun is now being fired. What acceleration is being applied to the aircraft (In m/s or kt/s)?
Bonus question: If there was infinite ammo and nothing like gun overheat, how long would it take to slow the plane down to stall speed, if initial speed was a usual A-10 speed.


texts: What is this line found above the door on many aircraft?

texts:
Many aircraft have this line above the door as seen in the photos below. What is it, and what is its purpose?
Source

Source


texts: How (and when) does Heathrow alternate arrival paths?

texts:
I've noticed that flights over Richmond (particularly arrivals) seem to have significantly reduced over the last few weeks. This is based on looking at Flightradar, as well as listening to the noise levels overhead.

I believe that Heathrow ATC alternates runways, holding patterns, and directions, but I'm finding it difficult to understand how and when these changes happen.

When do these flight path pattern changes happen, and potentially when will flights overhead Richmond might increase again?


texts: How does the heading selector on the ADF work?

texts:
How does the ADF indicator work in terms of pointing the needle in the direction of the NDB signal? I understand that the ADF needle points towards the direction of the NDB signal for a given frequency, but when a pilot tunes in the ADF signal, the heading ring does not change when the ADF was tuned into the frequency, only the direction of arrow changes.
So my question is, how do you use the heading selector when navigating with the ADF? And is it important to change the heading?

In the image, let's assume the aircraft is heading 030 degrees, but the heading on the ADF does not change to 030 degrees only the ADF needle changes its direction. Why is this?
If I were to turn from 030 degrees to 180 degrees, the needle would only change its direction not the heading of the ADF.


texts: Which radio altimeter is the Boeing 737NG call outs based on?

texts:
I'm wondering which of the two Radio Altimeters: Captain (left) or F/O (right), that the 737 does the RA callouts based on.

For instance, if the F/O's RA is slightly off, and passes 500ft before the captain's RA, does the aircraft call "500" when the first (in this case the F/O's RA) RA passes that altitude, or is it always based on the captain's RA?

Also, while on this topic, could someone confirm if the "Minimums" callout is always based on whatever is set on the Captain side, because to my knowledge, that is the case.


texts: What would they call the US President's personal plane?

texts:
Air Force One is called that because it is operated by the Air Force.  The President's personal helicopter is called Marine One because it is operated by the Marines.

What would the President's personal aircraft be called?


texts: How can you calculate the required tailplane force to ensure steady state flight?

texts: Consider a max forward and a max aft CG position.


texts: Does F-35 flight stick have a trackball?

texts:
There is a trackball-looking thing on the side of F-35's side stick.
What is this? Is this actually a trackball?

There is also another round looking "button", although a bit different from the first one, on the lower back of the stick:

(The images are from here)


texts: Why can't I find a tail number in the FAA registery?

texts:
I'm reviewing my pilot logbook in preparation to move everything over to my EFB logbook. As part of that process, I have been looking up the various aircraft I've flown in the FAA registry to get details about those aircraft to make my log complete (my digital pilot logbook tracks more information on an aircraft than my paper logbook and I'd like to have the details for my own nostalgic purposes).

One particular aircraft I flew in 2005, N7635A, is nowhere to be found. Clearly the plane existed - I flew it! And it's in my logbook 3 times complete with my CFI instructor's signatures in those entries, so he seems to have thought the plane existed as well.

When I look up N7635A, I get a Cessna 180 (circa 1960s). I never flew a 180 (seems like I would have noticed that since the rest of the fleet was made up of 2002 - 2004 Cessna 172SPs and they all had that new plane smell). https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=7635A

My first thought was maybe the FAA drops registration records if a plane leaves the country - but that Cessna 180 is deregistered because it was exported to Canada. Also, another plane I flew, N65460, is also deregistered but still has a record with the FAA: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=65460

I have tried different combinations:

N7635A - 1960 Cessna 180 (wrong plane)
N763SA - 1979 Cessna 152 (wrong plane)
N7G35A - not valid
N7G3SA - not valid

N60432 is another mystery 172S in my logbook but that's from 2013 and I only have a single entry for that one.

Do I have a correct understanding of the FAA N-Number registry? Am I wrong to think it's a complete record of all FAA N-Number registrations (going back to at least 1960)?


texts: Is there any benefit to folding wings on commercial aircraft?

texts: This video shows NASA researching folding wings, in what looks like a model of an airliner. What would be the benefit to this technology?


texts: Did people really hand-start big bombers in WWII?

texts: I am not a pilot so I don't know anything about hand starting propeller aircraft. But I wonder how easily can the propeller fire up unexpectedly during the procedure even if it's done right. Whenever I see an old WWII movie and the guys are turning those big props on the bombers, I always think of that question.


texts: What should I do if the FAA requests health records that no longer exist?

texts: I am working on obtaining my FAA Medical Certificate and I was deferred.  I received a request for more information and one of the items that was requested were medical records related to a surgery I had as a young child over 30 years ago and the records no longer exist?  How can I resolve this?


texts: Why, and how, are barometric altimeters accurate enough for approach and landing?

texts:
The barometric altimeter is used as the primary altitude indicator during approach and landing right up until the aircraft crosses the threshold (after which the radar altimeter takes over and makes the “thirty...twenty...ten” calls), as it - unlike the radar altimeter - can’t be fooled by mountains or canyons lying across the descent path.

Yet barometric altimeters have problems of their own:

They require an accurate knowledge of the local surface pressure at all times... and atmospheric pressure can change very rapidly, both from time to time and from place to place.
They require that the aircraft be at a specific, constant angle of attack in order to give accurate readings; if the aircraft is flying at a higher angle than that for which the pitot-static system is calibrated, ram air will be forced into the static ports, resulting in a falsely low altimeter reading.
They rely on the aircraft’s static ports, which can be blocked by things such as rain, icing, or duct tape (fortunately, this is uncommon nowadays, as most static ports are heated, and most maintenance techs quadruple-check that they haven’t left anything covering the ports).

Given these vagaries of barometric altimeters, why don’t we see lots of crashes from situations like these:

You break out of the clouds at what your altimeter says is 3000 feet; unfortunately for you, it turns out the pressure’s dropped since the airport’s altimeter setting was last broadcast, and you’re about to hit the ground (either this or the following could, in the wrong circumstances, be exacerbated by torrential rain, which commonly occurs in conjunction with low-pressure systems, and can potentially be ingested by insufficiently-heated static ports, resulting in an even-more-falsely-high altimeter reading).
While on approach, you enter a localised low-pressure cell that the airport’s AWOS, being at the airport rather than back along the approach path, doesn’t know about.  Seeing your altitude apparently ballooning up, you idle the throttles and push the nose over to correct the altitude excursion; unfortunately, since you were never actually too high in the first place, this action instead sends you below the glidepath, and straight into the ground.
During a go-around, you set TOGA power on the throttles and pull back on the yoke; as the elevators are quicker to respond than the engines, the aircraft pitches up before it can accelerate much, resulting in the aircraft’s angle of attack temporarily increasing.  Ram air enters the static ports, the altimeter says you’re lower than you actually are, and, in an attempt to avoid hitting the ground, you pull the yoke as far back as it’ll go, stalling the aircraft.


texts:
Look at the Learjet, Embraer and Boeing noses which are kinda pointy - drag efficiency aside, how do they come to the final design of the nose?

I’m talking from an aesthetic point of view - how do they design them to be aestheticly pleasing as they are?

By hand, CAD software or other? I don’t think it’s random guesswork I produce what looks good and what doesn’t - do my question is: how do they make them noses?

I don’t think in the early days of the 737 they had advance mesh modeling like we do now!


texts: Where can I find an ATM simulation software to investigate traffic flow capacities?

texts:
Does anyone know what software is suitable to investigate air traffic flow capacities in various FIR's / routes. I need to see the effect of temporary reserved ares due to military activities, weather, changes of routing due to LOAs. Taking into account meteorological data would be advantage but it is not necessary.

It would be great if it will be possible to emphesize (colours, histogram, ...). usage of FIR areas.

What kind of software tools are used by EUROCONTROL or ATM consultancy firms providing this service. What standard tools commercially available (or for free)?


texts: What is the fastest recorded backward flying plane?

texts:
It is a well known fact that some planes like the Antonov An-2 can fly backwards since their stall speed is lower than the speed of the winds they can stably fly into. My question is what is the fastest recorded backward flying plane and is there video of this phenomenon?

In response to the comments by @Simon et al the term backwards was vague - backwards relative to the ground would have been more accurate.


texts: What qualifies as a "takeoff" and "landing" in currency requirements?

texts:
I just met my night-time currency requirements at KONT.

Landing and taking off from a 12000 foot runway in a Cessna 152 got me to thinking (always dangerous, I know).

There's more than enough room to land to a full stop, take off, climb to (e.g. 50 feet AGL), then immediately land again to a full stop without needing to go around the pattern.

Could doing the above count as two takeoffs and landings?

Perusing FAR 61.57 did not give me an answer.

Now I'm not suggesting that this is a good idea, but brings up a few questions;

1)  Is this a legal maneuver?

2) If so, would it meet currency requirements? (If not, chapter/verse of the regulations kindly requested).

3)  Assuming it's ok with the tower, how would I request such a move?


texts: Can the RAM AIR valve cause depressurization on the CRJ-900?

texts:
On the CRJ-900 AIR-CONDITIONING panel there is a RAM AIR switch light which opens a valve and allows air from the ram air scoop to enter the mixing manifold for distribution to both the flight deck and passenger cabin.

What would happen if the valve were opened at high altitude? Would this cause depressurization?

When I received CL-65 type rating I was taught that there was a protection that would prevent the valve from opening. I have also heard this was a mistake in the manuals and that it would open and cause depressurization. I have also been told that there is a one-way check valve inline with the ram air duct to prevent depressurization, but I’ve never seen a source for any of this information.

If anyone has an answer I’d appreciate citing some schematics or Bombardier manuals to back it up.

Update

I heard something. It's second-hand information from someone who worked at Bombardier when the CRJ was certified. This person said that there is no check valve on the RAM AIR valve, but the cabin outflow valves will close, compensating for the loss of pressure from the RAM AIR valve being open.

The cabin outflow valves should close completely as they are designed to prevent the cabin altitude from exceeding approximately 14,500 feet. This wouldn't prevent higher cabin altitudes if the ram air valve stayed open at a high altitude.

I still want a cited answer, but this is the first answer I've heard that makes sense to me.


texts: Do helicopters have an auto hover system?

texts:
I'm not a helicopter pilot. The way I understand it, helicopter pilots have to constantly make small adjustments to make a helicopter hover steadily at a certain point in space, just like fixed wing pilots flying in close formations.

Are there any systems which, when engaged, will measure the helicopter's movement with gyroscopes and accelerometers, and automatically compensate for small deviations?


texts: What are the rules regarding (HUD) Head-up displays, especially glasses type?

texts:
What are the relevant regulations regarding use of HUD displays in non-military aviation?

The specific application in mind would involve providing information to pilots of turboprop survey aircraft flying VFR at about 100m altitude so it's of benefit to have the pilots' focus on what's going on out the window.


texts: I wonder if it's possible to make a "compressed air" turbine engine

texts: I wonder if it's possible to make an efficient turbine engine that uses only hot compressed air to move but only that, meaning there is no ignition involved. To put it simple can we use compressors like turbo or superchargers to make a small turbine engine that will be able to move (not lift) 100+ kilos at high speed, well lets say around 40km/h (25 m/h)? I've studied it a bit and to actually know i need to make it but before that i thought to ask people that know certainly more than i do. Also if you can think of a way to do it i'd love to hear it cause iv'e thought of something but it might not work (i guess that's the fun of it tho doing tests and rebuilding and stuff). Ok, in addition to all that let's say that power for this comes from batteries and it's meant to work for short periods of time.


texts: Will a non-certified GPS source work the same in ADS-B mandated airspace?

texts: What happens if you use a non-WAAS GPS position source in ADS-B mandated airspace? Doesn't it work the same, except for the positional accuracy?


texts: What were the advantages of the L-1011 AoA sensor design?

texts:
The Lockheed L-1011 had an unusual type of AoA sensor. Instead of the usual vanes it used a tube with two rows of holes in it about 90° apart. A diaphragm sensed the pressure differential between the two sets of holes and a motor adjusted the sensor until the differential went away. The AoA was them determined from the angle the sensor was to the fuselage.

 Source: NTSB accident report TWA 843

This seems particularly complex, requiring a motor and possibly introducing lag into the reading. Why did Lockheed decide on such an unusual sensor design? Does it have some a advantages to a conventional vane? Was it used on any other aircraft besides the L-1011?


texts: Why can’t more older 737s be retrofitted with more newer winglets?

texts:
Some background: there are four different types of winglet that have been used on various 737s over the years.

The mini winglet is used to retrofit 737-200s (one of the two 737 Original variants, the other being the 737-100).  It is basically a tiny trapezoidal tab riveted to the rear portion of the wingtip.

(Image by Julian Whitelaw at airliners.net, via meisam nemati here at AvSE.)

The blended winglet is what most people think of when they hear the word “winglet” - an attachment that looks like someone simply extended the wingtip and then bent it up to near-vertical.  It was factory-installed on all 737 Next Generation variants (the 737-600/-700/-800/-900) for the first two decades of production, and has also been retrofitted on most of the 737 Classic models (the 737-300/-400/-500) that remain in service.

(Image by Ralf Roletschek at Fahrradtechnik auf fahrradmonteur.de via Wikimedia Commons, modified by Altair78 at Wikimedia Commons.)

The split-scimitar winglet has replaced the blended winglet on the last few years of the Next Generation production line; it is shaped somewhat like the blended winglet, but a) is swooshed rearwards at its upper tip, as opposed to the simple trapezoidal tip of the blended winglet, and b) has an additional scimitar-shaped, rearward-swept fin projecting from the outside of the upbend in the winglet.

(Image by Mnts at Wikimedia Commons.)

The MAX winglet is used on the 737 MAX series (737 MAX 7/8/9/10); it, too, is a split winglet,1 but of a simpler shape than the split-scimitar winglet, looking much like someone extended the wingtip outwards, then split its upper and lower surfaces away from each other and bent them upwards and downwards, respectively, to form what looks remarkably like a glorified Airbus wingtip fence.

(Image by Aka The Beav at Flickr, via Helmy oved at Wikimedia Commons, modified by Altair78 at Wikimedia Commons.)

Now for what I’m curious about:

Although the 737-100 (the original Original) was produced in smaller numbers than the 737-200 and is no longer in service, it still hung on with various operators past the turn of the millennium; why weren’t any -100s also retrofitted with mini winglets, given that the -200 is basically just a stretched -100 with more fuel capacity?
Given that the blended winglet, despite being originally designed for the Next Generation wing, was retrofitted on the vast majority of the Classic fleet with little to no trouble, why couldn’t it also be retrofitted on the remaining Originals, given that the Classics are essentially CFM56-engined, (sometimes) stretched -200s?
Seeing as the Next-Generation-designed blended winglet was easily adopted for the earlier Classics, what keeps the split-scimitar winglet, likewise designed for the Next Generation wing, from also being retrofitted to the Classics?

(Yes, I know that this is three questions rather than one, but I felt it was better to have one question asking three closely-related questions than to clutter up the homepage with three separate but near-identical questions.)

1: As for why Boeing went to the trouble of developing two different styles of split winglet for the two in-production 737 families, that’s a different question.


texts: Is it possible for a civilian to use a VORTAC station?

texts: Suppose you have a Cessna 208 Grand Caravan Amphibian and you want to use VORTAC stations on military bases (or somewhere else). Is it possible? Is it legal?


texts: Does the F-35B use its articulating rear jet nozzle for thrust vectoring?


texts: How would the wave drag of an elongated Sears–Haack body change with a cylindrical mid section?

texts: Would a Sears–Haack body have the same wave drag as the same body with cylinder of the same diameter placed in the middle, between two halves of the Sears–Haack?


texts: For the elliptical wing, which property is actually elliptically distributed?

texts:
Elliptical wings are sometimes used:

One of the 50 Spitfire still flying in the World. Source
I read it's because this shape allows a perfect distribution of aerodynamic forces. But actually:

What is actually elliptical in the elliptical wing?
What is regularly distributed: Is it lift? or drag? or something else?


texts: Where does one request a VFR transition route through class B?

texts:
Other than staying outside class B until being cleared in, is the point where one requests a transition route important? For example, the SFO B coastline transition is shown as starting up at San Rafael in the north. But one could also fly as far south as SAU below 5000 or Lake Merced below 3000 outside the Bravo before having to ask for clearance. So my question is whether the intent is that one should start at the mapped limits of the transition routes or whether one can ask for them anywhere as long as you're outside the Bravo?

Vaguely related question: the FAA presentation on the latest version of the SFO B shows that the intention for the coastline transition is "at or above 3500". Is this documented somewhere other than in this random PDF from a 2-year-old presentation?


texts: Why wouldn't KJFK offer the ILS for 22L?

texts:
(Source: Flightradar24)
The above was from last Sunday around 17z. I was watching FR24 with the ATC feed. The airport was operating in 'arrival priority' with approaches to both 13L (Canarsie) and 22L.
Both directions were offered their respective VOR approach. Authorized carriers such as JetBlue and Alaska Airlines requested the RNAV RNP 13L (not publicly published by the FAA, yet).
My question is why wasn't the ILS offered for 22L? I checked the NOTAMs and the serviceability of the ILS was not there. And since the VOR is an instrument approach, it wouldn't quite fit the visual vs. instrument asked about here. A 4-year old post on airliners.net blames LaGuardia (LGA):

JFK will frequently land with max crosswind or tailwind components and frequently uses off set VOR approaches to minimums before switching to the preferred ILS.
Why? LaGuardia and the airspace to the north.

While yes the VOR is offset (232° vs. 224°), it's not a big offset that would free a chunk of airspace for LGA when it vectors its inbounds via a left downwind for runway 22. To be sure I superimposed both plates by aligning the 604' structure (shown below).


texts: Why does power help us maintain altitude in slow flight?

texts:
I was asked this question and didn’t know how to phrase a nice and easy explanation.
What I said is- well because drag is now increasing Un- proportionally to lift, we need something to generate more lift, and since pitching up like we would do in normal speeds isn’t an option because it would just increase drag more, our only way to create more lift is increase thrust- and in so increase that vertical component of thrust that acts as lift and help us maintain altitude.
Am I right in explaining it like that? And is there a nicer and simpler way to explain that?
Something with the 4 forces and thrust-drag and lift-weight couples?
Thanks!


texts: What are the benefits of an FAA over an ICAO license, and vice versa?

texts:
I will study for commercial pilot in May but I don´t know where I should study. I have 2 really good schools, one is in Canada (ICAO) the other one is in Florida (FAA),

What are the advantages and/or differences of both licenses when it comes to a career in international aviation and what potential differences may it have in career and training paths.

If we only talk about license not about schools.


texts: Have there ever been forward-swept horizontal stabilizers, and what would be its advantages?

texts: After going over one of my older questions about forward swept wings, I realize I have never seen a forwards-swept horizontal stabilizer. Do they exist? What would be their advantages, if any?


texts: Is there a real risk of ingesting FOD into jet engines when using thrust reversers?

texts:
In the discussion of Why doesn't the A380 use its outboard thrust reversers, one of the reasons given was that engines 1 and 4 would be at great risk of ingesting debris. It was pointed out that the 747 uses reversers on all 4 engines, and it's just as big (overhanging edge of runway). So I asked in a comment:

If there is fear that the outboard engines would ingest crap (FOD)
because they overhang the edge of the runway, why wouldn't that also
apply to takeoff, when the outboard engines are presumably at high
thrust? Additional: I realize that the jet blast is straight back, but suction on the front of the engine is pretty strong, too (enough to inhale a baggage cart).
Does an engine at reverse thrust kick air (and debris) far enough
forward that there is a real risk of ingestion and FOD?
Could that be negated by designing the reverse thrusters to go
mostly sideways?

I was asked to repost as a separate question, so here it is...


texts: Why did the B-52 never have a JT4A-powered version?

texts:
All versions of the B-52 use the Pratt & Whitney JT3C turbojet (except for the last version, the B-52H, which uses the JT3D low-bypass turbofan instead).

Problem: the JT3C is a horribly anemic engine, especially the early versions used on the A-E (producing a mere 44.5 kN per engine on the B-52A, increasing only to 46.7 kN/engine on the B-E models).  The engines used on the F and G did better, but still topped out at 61.2 kN each.  Due to this low engine thrust, the A through G models of the B-52 all required the use of water injection (with the associated weight and space penalties) to augment their engines' thrust for takeoff, without which the aircraft would have been incapable of becoming airborne.

For this reason, the other major users of the JT3C (the 707 and DC-8 airliners) promptly switched over to the more powerful JT4A turbojet when it (the JT4A) came on the market; the JT4A provided up to 77.8 kN of thrust, allowing the JT4A-engined versions of these aircraft to do away with the heavy and complicated water-injection system.

In contrast, the B-52 never switched over to the JT4A, even though, as a heavy bomber aircraft stuffed to the gills with fuel and ordnance, it would have benefited even more from the added engine power than the airliners did.

Why did the B-52 stick to the JT3C (until they finally jumped ship for the JT3D), and not go for the JT4A when it became available?


texts: Which moments are acting on a flying airplane?

texts:
I would like to ask some clarifying questions regarding the moments acting on a flying airplane.

My understanding is that there are following force:

Weight (pointing down and applied to the CG of the plane)
Lift from the wing (pointing up and applied to the aerodynamic center AC)
Lift from the horizontal stabilizer in the tail (this resultant force is pointing down, it is smaller than Lift_wings, and it is applied to the AC of the tail).

The airfoil, on its own, also has an aerodynamic moment (positive)
   which would make the wing rotate nose-up about the CG of the wing
   itself if the wing was placed free in the wind stream. However, the aerodynamic moment about the aerodynamic center is constant negative (nose down). Is that correct? The physical effect is the nose up intrinsic moment of the cambered wing due to the fact that the force on the bottom and the force on the top of the wing do not act along the same line of action.

For longitudinal stability, are the participating moments the moment due to Weight, the moment due to the wing lift and the moment due to the horizontal
 stabilizer that need to add to a zero resultant moment? Can the positive aerodynamic torque of the wing be ignored because much smaller in magnitude than the other torques?

In most planes, starting from the leading edge of the wing, the aerodynamic center AC of the wing is placed behind the plane's CG. How far behind CG should the wing AC be placed? The placement of the tail's AC should easily derives from the moment equilibrium equation (sum of moments equal to zero). I realized that some big airplanes have the CG behind the wing AC. In that case, the lift from the tail is force always directed upward and not downward like when the CG is in front of the wing AC.


texts: Why would the runway separation for parallel triple simultaneous precision approaches be dependent on airport elevation?

texts:
Based on FAA advisory circular AC 150/5300-13A, Airport Design, when operating triple simultaneous precision instrument approaches the parallel runway separation could be reduced from 5000 feet to 4300 feet if the airport elevation is above than 1000 feet:

  Triple simultaneous precision instrument approaches for airports below
  1,000 feet (305 m) elevation normally require parallel runway
  centerline separation of 5,000 feet (1524 m) between adjacent runways.
  Triple simultaneous precision instrument approaches for airport
  elevations at and above 1,000 feet (305 m) and reduction in separation
  are currently under study by the FAA. In the interim, the FAA will, on
  a case-by-case basis, consider proposals utilizing separations down to
  a minimum of 4,300 feet (1311 m) where a 5,000-foot (1524 m)
  separation is impractical or the airport elevation is at or above
  1,000 feet (305 m). Reduction of separation may require special radar,
  monitoring equipment, etc.

What is the theory behind the advice?


texts: What are these things under Airliners wing?

texts: As the picture below, what are these triangle components for? I find these normally installed under the Flaps. Thanks!!


texts: How would the Airbus A320 PFD respond to failure of all pitot and AOA sensors?

texts: In theory, if all 3 pitot tubes and all 3 AOA-sensors would fail simultaneously for a period of time, could the PFD still deliver correct roll angle and horizontal displays? How would the plane calculate the actual airspeed?


texts: Do aeroplanes have to balance torque like helicopters?

texts: Helicopters need a tail rotor to balance the torque reaction that tends to rotate the main body sideways. Doesnt a single-engine plane suffer the same problem? I would imagine that (for example) the left wing would dip lower than the right due to the torque. How is it countered?


texts: What would happen if I bank a helicopter then pull hard on the cyclic?

texts:
Prompted by Simon's response to my question here, I will ask another question about reality.

If I:

Start with a AH-6 helicopter in a hover
Pitch down slightly to accelerate, then slowly increase collective to gain speed until max collective is applied and the airspeed is near Vne
Roll the helicopter to about 70 degrees of bank
Pull back hard on the cyclic

(Basically it can be described as trying to fly a Red Bull race in a helicopter)

What would happen?


texts: What is a localiser back-course approach and how does it work?

texts: What does back-course approach mean ? How much signal strength should the back lobe of ILS should have in order to trace it and commence landing. How common is this type of landing for a pilot. What all instruments are required for this type of landing?


texts: How does an ADIRU convert ram air pressure from the Pitot tube into Airspeed?

texts:
I know how the analog Airspeed Indicator shows the Airspeed from the ram air pressure from the pitot tube. But I'd like to know how an ADIRU converts the raw pressure data to Airspeed that is displayed on a PFD.

What sensor is used for this purpose?
What exactly happens inside the ADIRU?
Does the sensor and / or procedure differ from unit to unit?


texts: Why is there always a fire truck present before refuelling?

texts:
Whenever I fly within Europe, I notice there is always a fire truck present for refuelling before takeoff.

Is this standard procedure for every flight in commercial aviation? If yes, is this a global thing or just a European one?


texts: What is the tail strike pitch angle of the ATR-72?

texts: What is the maximum pitch attitude an ATR-72 can be during takeoff or landing, without having a tail strike?


texts: What is the cabin noise hertz in typical commercial aircrafts?

texts: In cabin, we hear noises in commercial aircrafts. Wondering if it is in general over or under 100 hz. There should be a band width. Thanks!


texts: Venturi´s effect states that air over the wing accelerates and static pressure drops. There's a different theory which states that as air is viscous, once it impacts the wing, slows down... Can those two theories coexist?


texts: What time zone is used for operating an airplane?

texts:
This might be a silly question but my thinking was the following:

There has to be a definition of time in an airplane for the logging of data and so on, but what definition would that be assuming a flight goes across timezones?

Would it be the local time at the airport of departure? Or at that of arrival? or maybe even a third, commonly agreed upon time (e.g., GMT)?

The idea came from a story of a friend that was traveling with the ship from Italy (GMT+1) to Greece (GMT+2). The cafeteria on board had a sign saying that it opens at 14:00, but on 14:20 local Italy time, while the ship was anchored in Italy, he was denied service by the crew saying that the sign was referring to Greece local time; where the ship "belongs".


texts: How does a CFI know what endorsements to give?

texts: I am trying to figure out how a CFI knows what endorsements to give. Obviously AC 61-65E lays them out but what if someone is coming from a unique situation? Let's say someone has a helicopter license and wants to get their private pilot? Do they have to take a knowledge test? What if someone is a sports pilot and wants to upgrade to a private pilot, what do they have to do? How do you figure it out?


texts: What is the certification basis of tactical UAVs like MALE RPAS?

texts:
What is the certification basis of Medium Altitude Long Endurance Remotely Piloted Aircraft System (MALE RPAS) tactical UAVs?
Is it based on CS-25?


texts: Is it possible to export NMEA data from a Garmin GDL-39 to a custom Android App?

texts: Hi I was wondering if it's possible to receive NMEA data from a Garmin GDL 39 on an Android device (preferred over Bluetooth) as I can't find any information out there on it.


texts: What is the highest muzzle velocity of a gun on any fighter aircraft?

texts:
I'm looking for the greatest muzzle velocity of a gun on any fighter aircraft.

I looked up the GAU-8 Avenger from the A10 Warthog first. Its muzzle velocity is 1,070 m/s, which is pretty darn high (almost 3 times the speed of sound). Are there any faster bullets out there from an aircraft gun?

Note: Don't really care about the firing rate (rounds per minute), or bullet caliber. All I'm looking for is highest muzzle velocity.


texts: Is it possible to selectively deactivate alarms?

texts:
My question is restricted to Airbus an Boeing's best sellers, namely the A320 and the B737. If relevant, answer can be extended to other types.

In those aircraft, there are multiple possible alarms (GPWS, stall warning, unwanted altitude excursion,...). Some alarms may be triggered by faulty sensors and deactivated. As an example, I can cite the "Too low! Gear!" of the TK1951 due to faulty radio altimeter. When identifying an alarm is a false alarm, it should be nice to deactivate this alarm and only this alarm. My understanding is that you can mute an alarm when triggered but nothing prevent this alarm to be triggered again later in the flight, but I don't know if my understanding is right.

Is it possible (technically) to deactivate a specific alarm (let's say "Too low! gear!") for the rest of the flight after identifying this is a false alarm? In other word, is it possible to prevent a specific alarm from being triggered without impacting the other alarms?

EDIT: the main difference with the question Can pilots turn off warning alarms? Re: Aeroperu Flight 603 is that I want to know if an alarm can be turned off for the remaining of the flight, not only "whilst the condition exists.".


texts: How should we think of 'layers' of air flow?

texts:
Do a search for "boundary layer" or "laminar flow" on this site, and you'll find plenty of things to read.

They'll talk about "the boundary layer", "flow separation" and so on, as though it were completely obvious what they actually were. Sometimes, they'll even be illustrated with diagrams representing the strata in the flow of air.

I'm no physicist, and this talk and these diagrams make me imagine the fluid equivalent of plywood, or expensive paper handkerchiefs, constructed of discrete layers of material that can be readily identified as such and peeled away from each other.

Is that really how these layers of moving air work? Is the boundary layer over an aircraft's wing like a discrete sheet, with a clear and distinct boundary between the next discrete layer? Or is there a smooth continuum, rather than a distinct step, between the layers and their properties?

Do distinct layers exist more in the conceptual analysis of aerodynamic behaviour than they do in readily identifiable physical entities?

If you were to plot a graph representing some property of the air flow (say its velocity, direction, pressure or turbulence) against distance from the surface of the wing, what sort of shape would the curve have?

In short: how should we imagine these layers?


texts: What's with this non-exit Exit sign on Delta CRJs?

texts:
I have the pleasure of frequently flying Delta (i.e. Delta Connection) flights on CRJ-700 and CRJ-900 aircraft.  All of them have a bogus EXIT sign between First Class and the main cabin:

This is roughly half-way between the front doors and the wing exits.  This seems to me to make nonsense of any safety regulations requiring EXIT signage.


texts: How do tugs push back aircraft with 2 nose gears such as the Antonov 225?


texts: Why did some Caravelles have a very long dorsal fin?

texts:
(Source)

Why did some Sud Aviation Caravelles have a very long dorsal fin stretching half the fuselage?

Initially I thought it's to keep the fin low to fit in existing hangars as a selling point, but the variant shown above (10B3 Super B) can also be found without this fin:

(Source)

There are two competing theories on airliners.net forums. One of them says it's fuselage strengthening for over-water flights in case of ditching. The other is a housing for an optional HF antenna. As far as I know, an old HF antenna was a stretched wire.

I checked the English, French, and Swedish Wikipedia articles, only the Swedish mentions it:

  The aircraft was also equipped with a long dorsal fin (Google translate).

A Flight issue from 1956 does not show the fin in their cutaway (the article also does not mention it).


texts: On acquiring an aircraft for my own PPL training and later use

texts:
I know that this matter has already been discussed in several other questions but the aircraft under consideration were almost exclusively Piper Warriors or a Cessna 172s which are 40 year old designs and heavy on fuel consumption.

Instead, I am considering light sport aircraft such as a Blackshape Prime or a Sling 2, for instance. I'd prefer a Blackshape Prime fitted with a CSU.

As I am still half-way towards obtaining my PPL, my question would be the following one: would it financially and technically (from a skill-set building perspective) make sense to acquire such an aircraft and lease it back to a school to do my training?

One of the school at my airport has two Sling 2 aircraft and they're quite popular with students. Most Warriors and 172s are now in their 3rd or 4th decade and seem to have run their course. Financially, in Australia, the dual hourly rate on a Piper or 172 is in the AUD 360 - 400 range, which includes AUD 100 for the instructor whereas dual rate on a Sling 2 is just about AUD 280, which makes it much more attractive to students and at no extra expense to the school.

Would it therefore be a good idea to buy a sport light aircraft such as those mentioned and lease it back to the school? Am I missing anything that is specific to them that still makes learning in Warriors and 172s relevant? Thanks for your inputs.


texts: What is the name of the movement which is carried out by plane beginning from the runway and ending at takeoff?

texts: What is the name of the movement which begins after the plane lines up on the runway and takeoff clearance is received, and ends when the plane lifts off from the runway? Is it also called as 'taxiing'? I know that roll-out is used for plane's decelerating movement on the runway after landing; but what is the name of vice-versa?


texts: Why do aircraft have an unusable amount of fuel?

texts:
I learned from this question that a Cessna 152 holds 5.6 litres of fuel that it can't use.

Why would it be designed to hold fuel that it cannot burn, especially since water contamination of fuel is a concern?


texts: Does Boeing use a similar display to Airbus ECAM to view a particular system?

texts: Airbus has a dedicated ECAM panel forward of the throttles which is used to select a system for display on the LCD. Is there a similar panel used to select a particular system for display on Boeing's EICAS?


texts:
When the plain "wing area" is given in basic aircraft specifications, what area does it usually refer to? Is the same area used for calculating the wing loading?

For example I have a fuller specification in front of me which gives areas for:

Main plane with ailerons
Main plane with ailerons and body centre section
Aileron, total
Tail plane
Elevators, two

If this were being condensed to a single value for "wing area", which of these would be used? Obviously, for something with a very long root chord such as a delta-wing jet, the areas with and without centre section will be very different, also leading to very different calculated wing loadings.

Has standard practice changed over the years?


texts: How is the cruise speed of an aircraft chosen?

texts:
Does cruising speed of aircraft depend upon mass of aircraft?

I am asking this because as lift is generated to overcome the gravitational forces ($mg$). And lift is proportional to square of the aircraft velocity.


texts: Why did the space shuttle use bias-ply tyres instead of radials?

texts:
Aircraft and automobile tyres can be divided into two main types, based on the orientation of the tyres’ body plies (the layers of tough fabric that form the main structural body of the tyre); radial tyres are built with the body plies laid perpendicular to the bead and tread (so that the body plies extend straight out radially - hence the name - from the tyre bead, straight across from one side to the other at a 90º angle beneath the tread, and straight in radially to the bead on the other side of the tyre), while bias-ply (or simply bias) tyres have the body plies laid at an oblique angle.
Radial tyres are the more common type by far, for very good reason; they are stronger than bias-ply tyres and wear much more slowly.
I was, thus, rather surprised to learn that the tyres used on the space shuttle’s main landing gear were of the older, weaker bias-ply type:

Wheels and Tires
[...]
The main landing gear tires are 44.5 by 21 inches and have 16 cord layers in a bias-ply design. They are normally inflated with nitrogen to a pressure of 370 pounds per square inch (psi). The maximum allowable load per main landing gear tire is 132,000 pounds. With a 60/40 percent tire load distribution, the maximum tire load on a strut is 220,000 pounds. The main gear tires are rated at 225 knots maximum ground speed and have a life of one landing.  [Shuttle Crew Operations Manual; my emphasis.]

The space shuttle’s main landing gear would seem to be one of the worst possible places to use bias-plies instead of radials; with each tyre carrying up to 59.9 tonnes (66 short tons) and having to cope with touchdown speeds in excess of 200 knots, it would seem imperative to use the strongest tyres available.  The magnitude of the stresses placed on these tyres was so great that, while most aircraft tyres can make it through dozens to hundreds of flights before having to be changed, the shuttle MLG tyres were rated for a grand total of one use before replacement.  Additionally, with only four MLG wheels per shuttle orbiter, even a single MLG tyre failure would significantly impair the vehicle’s braking capability, which is most emphatically not a good thing for something going as fast as a landing shuttle orbiter.  Given all this, one would think that radial tyres would be the obvious choice, hands down, for the shuttle’s main landing gear, since their greater strength and slower wear would considerably decrease the chance of a tyre failure upon landing - yet the shuttles instead used bias-ply tyres.  Why?


texts: Any info on very strange wing endings on this Stemme glider?

texts:
Do you have any info on this strange wing endings used on Stemme glider?

Source


texts: Where can I find examples of ADS-B surface (ground) position data?

texts:
To check my decoding it would be helpful to have some correct reference data for checking input and output as follows:

Input: 19-bit Compact Position Reporting (CPR) even latitude and longitude / odd latitude and longitude (decimal values are OK)

Correct output: Latitude and longitude in degrees (decimal)

Where can I find sample data that I can use for testing?


texts: What are the differences between fuel types (comparing with vehicles)?

texts:
I find it funny that at gas stations, generally you can purchase "regular" gasoline (in various octane levels) or diesel. At airports, generally you can purchase 100LL avgas or Jet-A.

Can you compare diesel to Jet-A, and "regular" gasoline to avgas? If so, what are the differences? Why are there only two classes of fuel - are there others that I don't know about?


texts: Before the Soviet Union collapsed, what was Russia's official ATC language?

texts:
In most (all?) countries today, the official language for ATC communications is English.

Before the Soviet Union collapsed, what was the official language for ATC communications in Russia and other Warsaw Pact countries? Was it Russian?


texts:
I have Flight Simulator 2008, and there were some really good lessons for student pilots.

Are there flight lessons in FlightSim X, either part of the software, or available from external sites?

The FSX Learning Center shows some, but it seems you can't use them.


texts: Why might a passenger jet fly at altitudes in a strong headwind when the winds are more favorable at a different altitude?

texts:
I was a passenger on an east to west flight recently. During the flight I was playing with Garmin Pilot's new "Flight profile" feature that nicely shows the wind speeds at various altitudes, and I noticed that we were flying against an 80+ knot headwind at FL320, but if we'd dropped to FL220 we'd shave about 40 knots of headwind. That seems pretty significant. A 1,000 NM flight with 355 knot ground speed (which we were cruising at) would save 17 minutes of cruise time with 40 knots less headwind. That's a 10% increase in efficiency.

So the question is, did we stay (or even plan in the first place) to fly at FL 320 the entire cruise portion of the flight simply due to ATC needing to keep us there for traffic routing purposes,
Is there an even larger increase in fuel efficiency between FL320 and FL220 than 10%,
or is the difference negligible enough that it's not worth asking for a different altitude from ATC,
or some other factor not considered here?


texts: Can I fly in the USA with an FAA ATP, if I don't have a commercial certificate?

texts:
I am Taiwanese and I have an FAA ATPL, but I don't have an FAA CPL.

Can I fly commercial operations in the US?


texts: What if you don't recognise an aircraft ATC is telling you about?

texts:
Often an ATS will warn you about other aircraft: when you're taxying and need to give way, or for land-after (and other conditional) clearances, or to warn of traffic in the area you're flying in. Usually they do this by naming the type of the traffic, and often you need to positively confirm whether you have the traffic in sight. For example:-

  "G-ABCD, report departing Squirrel in sight"
  "Affirm, traffic in sight, G-ABCD."
  "G-ABCD, behind the Squirrel, cross runway 18 behind, report vacated."
  "Behind the Squirrel, cross runway 18, wilco, G-ABCD."

What if the type of aircraft you're warned about is one you don't know? In an area with lots of vintage or experimental aircraft, you might not even know whether to look for a fixed-wing or a helo. I wouldn't want to say I have the traffic in sight if there's a risk I'm not looking at the same aircraft.

  "G-ABCD, report departing Squirrel in sight"
  "The what? Is there wildlife on the runway? G-ABCD"

Is there a standard way to explain the situation and disambiguate? Failing that, is there a concise way that will not be misunderstood over noisy radios?

(For the benefit of other readers who wouldn't recognise a Squirrel: it's a helicopter, and the local police operate one out of Cambridge. It was the first obscure-sounding aircraft name I could think of to use as an example.)


texts: Can short buildings near an airport affect runway winds?

texts:
Reddit user u/ywgflyer contends for CYYZ, Toronto International Airport,

23 is the "good" runway. The 24s are garbage in a crosswind because of the localized wind effect that all the hotels (and the terminal) have. I've never had a windshear problem on 23, but I've gone around several times on 24R with a crosswind from the right.

I never visited CYYZ. But I just roamed CYYZ on Google Maps. I see many short hotels, maximum 7 floors? I see no tall edifices in or near CYYZ, except the two? ATC towers?

But let's hypothesize that  buildings near airport create these localized wind effects. How can these buildings erect in first place? Won't airport's lawyers try to stop these edifices being erected on grounds of safety? But I don't know aviation, land, or planning law.


texts: How could I calculate the correct distance from the runway to be able to fly a continuous downwind to final turn?

texts:
I’m not even sure if this is a safe/allowed procedure at controlled airports so it is purely hypothetical.

Assuming there are calm winds at the field, is there a way to calculate the distance your plane must be from the centerline (see “x”) of the runway while on downwind, so that once you start your turn to base and final thereafter, in a constant rate turn (assume 3 deg./sec.), that you will end up rolling out on the centerline of the runway?

Speed changes (slows) by 27 knots from the beginning of the turn to the end of the turn.

Essentially, if I wanted to execute an 180 degree turn at 3 deg. per second, while slowing the airplane from traffic pattern speed (90 kts) to final approach speed (63 kts), how far away would I need to be from the runway while on downwind before beginning the maneuver? The goal is to be able to use this on any plane given their own specific traffic pattern speed and final approach to landing speed.


texts: I hear it a lot in engine design , I think that belongs to some phase about we can change the engine parameters according to requirements but I am not sure about it.


texts: How can pilots sleep or rest merely 1 hour after takeoff?

texts:
I screenshot this YouTube video. Because the A380 just attained FL250, the flight obviously commenced less than an hour ago.  At 14:28 the relief captain (Robert Juelicher) leaves the cockpit. At 14:37, ATC clears the flight to climb to FL320.

Doubtless, relief pilots are legally mandated to have well and sufficiently rested and slept before their flight.

So how can Juelicher  be expected to sleep or rest 1 hour just into the flight?
Or did the Pilot-in-Command (Juergens Raps exhibited below  in the screenshot) mis-speak? Is Juelicher expected to merely fritter away time (e.g. read a book) until his shift, not necessarily to sleep?


texts: What is the purpose of fins on the empennage on some helicopters?

texts:
The S-70 Black Hawk has some kind of movable surfaces on its tail, look:

Source: Airliners.net

They look like "elevators" on airplanes. Does anybody know what are these things for?


texts: Why does it feel like a plane stops in mid-air during approach?

texts: At some stage while on approach to an airport in a commercial jet, it feels like the plane is almost coming to a complete stop in mid-air. Is this maybe as a result of the flaps engaging or the landing gear creating drag?


texts: What UK aircraft looks like an Islander but with twin fins?

texts:
Driving on the M40 recently just south of Banbury, England, I saw a distinctive smallish plane I'm trying to identify — probably military from the dull grey/green color.

It looked a lot like the Islander, but:

It had a tailplane and twin fins
The tail boom was narrower in proportion to the body, and more distinct from the body than the Islander's is (I think I'm misremembering or mis-saw that part — I was driving on the motorway, after all)
The body may well have been a bit bulkier (or that may have been an illusion caused by the narrowness of the tail boom)
The wings had a normal-looking span for the size of the aircraft but were shorter front-to-back than seemed normal (to my very-much-not-expert eye)

Like the Islander it was a twin prop with a fairly pointy nose.

Does anyone have any idea what it was?


texts: How are "charter" and "passenger" flights defined in the AIDX standard?

texts: I'd like to know the difference between these flight types in the IATA AIDX standard; specifically, for use in fuel order notifications.


texts: I would like to get into aviation, but I have concern about the leaded gasoline used in most small engine planes.  How difficult will it be to avoid avgas while learning to fly?  And how should I go about doing this?  In particular, is it typical for flight schools to have diesel planes available for flight instruction, and is it reasonable for me to insist on this?


texts: For a flying wing airfoil, which AOA is to consider when selecting Cl?

texts:
I'm in the process of designing a flying wing. I'm trying to keep it a small as possible, so the lift coefficient is very crucial for me. I'm currently looking at some airfoils but most of them deliver the good Cl at AOA larger than 0.

My questions:

When deciding a lift coefficient --let's assume 0.5,-- should I choose an airfoil that provides me with a Cl of 0.5 at 0 AOA?
When the flying wing is cruising, the lift force needs to equal the weight, but does the flying wing cruise at 0 AOA or can it cruise at 3° of AOA so it can it can keep its altitude?


texts: Are fly-by-wire fighters protected in AoA?

texts:
When thinking about fly-by-wire, I always think about civilian aircraft (Dassault Falcon 7X, Airbus A350...) for which protections are implemented to ensure the aircraft stays in its designed flight envelope (load factor limits to avoid overstressing the airframe, AoA limits to avoid stall, bank angle limits to avoid inverted flight...). All these restrictions help maintaining the aircraft in a manageable situation while in flight. Some (e.g. pitch or bank angle limits) are OK for airliners but counterproductive for fighters. Other are clearly applicable to both (e.g. load factor. You don't want to overstress your airframe or risk a G-LOC).

My question concerns AoA protection. For fighters, I imagine this protection can avoid loss of roll control while stalling. Yet, some fighters are able to fly at AoA obviously beyond stall angle (e.g. during a cobra), suggesting this protection is not present.

Do fly-by-wire fighters have an AoA protection? If so does it prevent stall? (I can imagine a protection triggered only if a limit is reached for at least a certain amount of time, or a limit beyond stall angle but not far beyond.) Does it have to be deactivated for manoeuvre such as the cobra (I expect every system to be able to be deactivated on such aircraft)?


texts: Do pilots use the pedals in flight on planes with a sidestick (Airbus)?

texts: Do the pilots flying sidestick aircraft with fly-by-wire control systems, such as the Airbus A320, use the rudder pedals while in the air? Or does sidestick input affect both the rudder and the ailerons?


texts: How much does it cost extra to fly with one additional passenger?

texts: How much does it cost to fly an airplane (like a Boeing or Airbus) when  there's one extra passenger there, at an average speed of 475–500 knots (880–926 km/h; 547–575 mph)? That is, about 100kg extra, including clothes and luggage.


texts: How frequently do civilian aircraft have mechanical issues to which passengers are oblivious?

texts: I know that aircraft are pretty well built and maintained, but I am certain that while flying these aircraft also suffer from some or the other mechanical issues. I believe redundancy plays a huge part in keeping these aircraft in air, but how many times are the passengers really oblivious to the problems? What are some of the most common problems that pilots are used to?


texts: What is the dimensionally smallest 2-seat helicopter?

texts: Considering only a two place helicopters (2 crew, or 1 crew and 1 passenger).


texts: What are the ASTERIX CAT010 message types 005 and higher?

texts:
I am analyzing some surface radar recording data under Asterix CAT010 category. The document from Eurocontrol shows that there are 4 standardized message formats under this category:

001 Target Report
002 Start of Update Cycle
003 Periodic Status Message
004 Event-triggered Status Message

However, I could find some other types from 005 to even a few hundred.
May I know what are these message types referring to?


texts: How does the nitrogen generation system in a Boeing 777 work?

texts: How does the nitrogen generation system in a B777 work and how does it differ from that used in a B787? Any diagrams will be appreciated.


texts: Why does the Piper Malibu require a type rating?

texts:
The Wikipedia page on type ratings says that most single-engine piston aircraft are covered under a single class rating but under JAA regulations the Piper Malibu requires its own type rating. (I'm unsure as to whether these regulations still apply or if the JAA even still exists.)

What is different about the Malibu that would require its own type rating? And do other regulatory agencies (FAA, EASA) require this?


texts: Flight crews are limited to 100 flight hours a month and 1000 flight hours a year, and usually paid by flight hour too. But is it the same for cabin crews or do they have their own rules for monthly hours? Is there an aviation regulation regarding them (they are safety critical crew members after all) with an ICAO recommendation, or are they subject to just work laws of their home country?


texts: what are some of the effects of breaking the sound barrier?

texts: I have tried googling it, and nothing came up, please help! I am trying to figure out what happens after a jet/aircraft breaks the sound barrier.


texts: Why should passengers not delay donning emergency oxygen masks after they deploy from the overhead compartments?

texts:
Assumptions:

The typical oxygen generator, on a plane, lasts twelve to twenty minutes.
(Source: Gizmodo.com)
Even in the event of cabin decompression, the oxygen in the cabin does not disappear or extinguish instantaneously.
If 1 is correct, then after how long would the oxygen usually need to vanish?
Waiting 2-5 minutes after the mask drops does not harm or injure; but obviously one must not wait too long, and should apply the mask sooner than later.

The question is motivated by wishing to maximise the use of the oxygen mask, whose oxygen supply is limited.


texts: What procedures exist to take control from an "unsafe" pilot?

texts:
I was reading up on the Garuda Indonesia Flight 200 crash and a few questions came to mind, in summary the captain (PF), conducted an unsafe approach in which he did not heed multiple warnings from both the aircraft and the copilot (PM), and landed 860m past the threshold and at a speed of 221kts.

The wiki article also states: "The copilot failed to take control of the aircraft ...  as required by airline policy". This just got me wondering, what policy/procedures exist in outlining how to take control of an aircraft from an "unsafe" pilot. I know the procedure under normal circumstances is "my aircraft/your aircraft". But how would this be accomplished in a situation similar to Flight 200, where it seems the captain would have of been reluctant to hand over controls given his blatant disregard for all other safety measures.


texts: Can the ECS work in an unpressurized cabin?

texts:
Can you control the cabin temperature if the cabin is unpressurized? What if the "cabin" isn't really that big, like a fighter aircraft?

For example, could I cruise in comfort at 20,000 ft in an unpressurized cockpit with an oxygen mask and heater?


texts: Why don't TAWS systems provide automatic avoidance?

texts: After watching several episodes of "Air Disasters" where the pilots' response to a TAWS (terrain awareness and warning system) alert was, "huh, that can’t be right", and then they fly into the terrain. I am left wondering why don't these systems actively avoid the terrain (pull up) automatically?


texts: How does an aircraft maintain level flight while accelerating?

texts:
Let's assume a plane is initially moving at constant speed, level flight with a certain angle of attack. If the plane's thrust is increased, the plane's horizontal speed increases (at one point the drag force catches up and becomes again equal to thrust. The speed becomes constant at that point).

But while the speed is increasing, the lift would increase and would the plane start climbing. How can we keep the plane in horizontal level flight while the speed is increasing? Does increasing the thrust need to be simultaneously complemented with controlling some of the rear lift surfaces to oppose the natural lift increase due to the wing?


texts: Is the cargo door on this airplane really malfunctioning?

texts:
Recently, I saw that video:

EDIT: I removed the Facebook video link which would require sign up for anyone without an account. I've re-uploaded the video here:
https://vid.me/8WYI

In general, this guy's videos seem to me more like a "conspiracy theories" thing, but I hadn't the time to study them and find the underlying faulty logic. So, in that particular video, he claims that the cargo door of an aircraft wasn't working properly and the ground staff simply decided to use a heavy load on the lever in order to open it (or something like that).

Because of that incident the plane shouldn't be allowed to fly (that's what he claims) and also there is immediate safety concern for the people on the ground because of the weight they used.

My questions are:

Is the cargo door in that airplane really malfunctioning?
Do the ground staff follow a standard procedure for the "workaround"?
Although I understand that the way the weight is "hanged" on the that
lever is not a safe solution, my logic says that it could never fall
from that position. Am I right?


texts: How does a typical passenger jet come to a stop when it lands

texts:
Do the pilots of the plane simply reverse thrust of the engines after touchdown or are there brakes on the landing wheels that slow the plane just like a car? Or a combination of both?

What about prop-planes?


texts: Have there been any attempts to standardise pay across different aircraft types?

texts:
TL;DR: I'm hypothesising the cockpit experience and pay in small aircraft vs larger aircraft is disproportionate to the risk and responsibility.

I read the argument that pilot pay should be equal across all types, irrespective of it is an A320, A330 or A340 for instance.

The smaller aircraft have greater number of rotations every day, leading to greater workload and hence the pilot responsibility could be argued to be equal to that of a larger aircraft which spends (a lot) more time just cruising.
The bigger aircraft often operate to better, more equipped airports than their smaller counterparts. This again may put more load and responsibility on the pilots.
The bigger aircraft, while in some cases more complicated, may have more automated systems and assistance rather than greater pilot workload, although this of course depends on the aircraft.

I'm wondering if anybody (airline, union etc.) has done this or is trying to do implement it. It would be mighty unpopular among some pilots but I think there is a little bit of sense to the argument.

Why is this a problem?

It also causes the least (or less) experienced pilots to command the small aircraft, rather than perhaps a more sensible mix of age and experience.

Paying additionally by the years of experience makes sense to me, but not this push to constantly advance to get a higher salary.

As it stands, the only way to make more (aside from years of experience) is to upgrade to a larger aircraft type. Aside from requiring retraining (expensive type rating), it puts the pilot into a new aircraft (and possibly airports) he is unfamiliar with.


texts: How to read representations of pressure around an airfoil?

texts:
Actual representations found online

I selected 6 online representations of pressure around an airfoil, mostly using inconsistent symbolization of the pressure field.

Source of the individual pictures: Fig 1, fig 2, fig 3, fig 4, fig 5, fig 6

As visible, arrows can be found in nearly every combination of directions. On figure 4, pressures are about 2 hPa (200 Pa) and 5 hPa, which is not really understandable when pressure at sea level is about 1,000 hPa.

Last figure shows the pressure field in the cross-section, not only at the surface of the airfoil (which I believe is the case for the other figures).

Assumptions made to read the figures

By following the answers on this site, I know that the pressure on the lower side of the airfoil is greater than the pressure on the upper side. I also assume that the pressure on the upper side is lower than the ambient pressure, and the pressure on the lower side is greater than it. I believe the drawings are trying to depict these two aspects, but using different (and unspecified) conventions.

Probably the clearer convention is the one used on fig 6: Yellow is likely the ambient pressure, orange would be greater, green lower, blue even lower.

Questions

What are the usual pressures found around an airfoil, e.g. in cruise, at mid-span of a A320 wing (compared to the ambient pressure).
What is the most correct representation of the pressure field in the figures above?
Is there some conventional way used by engineers to depict the pressure field without ambiguity?


texts: Is there an audible warning on commercial aircraft if you try to land gear up?

texts:
In one of the comments on this question (under the accepted answer), someone remarks that

  Aircraft can legally fly without a system to alert the crew when they are landing with gear up, etc.

Are these systems installed on commercial aircraft as a legal requirement?