# All Questions

14,870 questions
153 views

### Why not separate out the two definitions of V-1 into two separate Vspeeds?

V1, officially the takeoff decision speed, has, somewhat infamously, two separate definitions: It is defined as the minimum speed at which, if one engine fails, the pilots can press to liftoff and ...
94 views

### Why is the F-16's service ceiling 50,000ft? [duplicate]

What defines the service ceiling for aircraft, in particular the F-16? I suppose, as with almost everything, this depends on the aircraft, the engine type, etc. While I'm fine with a comprehensive ...
503 views

### what type of sensors does the Boeing 737 MAX use for MCAS?

I can imagine there are several different ways to measure angle of attack (accelerometers, relative pressure measurements between pitot tubes, etc), but I'm curious which sensors the 737 MAX uses for ...
32 views

### In the compressor characteristic, what does this value represent?

$$? = \frac{m_t* \sqrt{T_3}}{P_3}$$ All I know is that it is a material property of a turbine, it has something to do with the mach number, and is used for calculating $W_T$. It's kinda similar to ...
182 views

### Could the S.H.I.E.L.D. C-17 actually have a sensible center of gravity?

In a question about whether tail surfaces add to lift, I thought of a fictional example where the tail surface very much adds to lift: The Agents of S.H.I.E.L.D C-17, highly modified and super-engined....
79 views

### What is a shroud (in aviation terms or engineering terms)?

Please can someone explain what a shroud is and give examples of types of shrouds and their uses on aircraft?
6k views

### Why is indicated airspeed rather than ground speed used during the takeoff roll?

My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or ...
126 views

### What plane model is this?

I thought it was a BAe 146/Avro RJ but the wing proportions don't seem to match. edit: Nevermind; I found it. It's an Ilyushin IL 76 out in Umm Al Quwain, UAE.
608 views

### Is the Boeing 737 MAX 8 MCAS exceptional in operating when autopilot is off?

To the uneducated reader it seems strange the Boeing 737 MAX 8 MCAS system only operates when autopilot is off. I understand the reasoning behind why it was implemented to operate when autopilot is ...
91 views

### Do left and right mic buttons control both headset microphones?

The aircraft I was flying today has a push to talk integrated button on each control yoke. I was sitting in the right seat, but my headset was plugged into the jacks on the left side of the cockpit. ...
202 views

### Smoking in the cockpit - how is this tracked?

A finding in the final report of US-Bangla Airlines Flight 211 crash is that the captain was smoking in the cockpit during the flight (page 46, section 3.1.2 e of the final report). My questions are: ...
111 views

### Has any jurisdiction mandated passenger training?

A chunk of pre-departure time for each flight is dedicated to a safety briefing for passengers that few passengers seem to pay attention to. In the aftermath of accidents, it has been revealed at ...
246 views

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

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 ...
747 views

### Why do newer 737s use two different styles of split winglets?

All new 737s use split-tip winglets, which are more efficient than the simpler blended winglets previously used. However, for no clear reason, they use two different types of split-tip winglet: New ...
69 views

### How do stealth aircraft operate from rough or contaminated fields without ruining their paint jobs?

While thinking about the MiG-29’s dedicated rough-field intakes, I started wondering about rough-field operations for other types of combat aircraft, and, naturally, since most new combat aircraft ...
168 views

### How do balloon pilots avoid birdstrikes?

Balloons, by their very nature, are at the mercy of the wind, and can’t maneuver out of the way of other objects except by (very slowly) climbing or descending. For this reason, mid-air collisions ...
47 views

### What does 'in-trim speed' mean with respect to Boeing 737 mis-trimming correction?

This question was prompted by discussions of the recent Boeing 737 MAX crashes, but it is not specifically about that variant. In Boeing's 737 NG Flight Crew Training Manual, in Chapter 8 (Non-Normal ...
245 views

### Do horizontal stabilisers provide any lift?

Do jumbo and smaller airliners' horizontal stabilizers provide any lift? Apart from maintaining the aircraft's angle of attack, can they perform the dual function that includes adding some lift as ...
62 views

### When is a CFII required to provide instrument training?

61.195(c) states: (c)Instrument rating. A flight instructor may conduct instrument training for the issuance of an instrument rating, a type rating not limited to VFR, or the instrument ...
86 views

### Why are there no RNAV (ILS) approaches?

While studying the PBN (FAA Order 8260.58A) and TERPS (FAA order 8260.3D) documents, I still have some trouble figuring part of the logic behind the naming and definitions of the published IAP Charts. ...
123 views

### How are Boeing jets referred to in the American airline industry? [on hold]

Boeing's main lines of commercial planes are named "7X7," from the 707 through the 787. My dad works for Boeing, and growing up, he always casually referred to the planes by the last two digits, e.g. "...
258 views

### How is device control software checked for quality?

Many, many reports on the now infamous MCAS suggest a software patch is forthcoming in the next several weeks that will address the confounding single point of failure with the two AOA sensors that ...
225 views

### Why did Air France flight 447 fail to recover from the stall? [on hold]

I have read the wikipedia entry about the accident but I don't understand why did the stall happen and why the plane couldn't recover from the stall. Correct me if I am wrong but I would think a ...
47 views

### What lights to use for a high-altitude weather balloon?

I am designing a high-altitude weather balloon for a college project. The balloon may fly at night, which means that, per FAA regulations, I need a light that is visible for 5 miles. Does anyone ...
107 views

### If all control surfaces were disabled, could a passenger plane be controlled by distribution of the passengers?

Let's assume that a large military plane has its control surfaces disabled in combat. The engine(s) can still be controlled. There is a substantial number of ground forces being transported. In ...
49 views

### Is overall pressure ratio same as compressor pressure ratio for a gas turbine engine?

For a typical gas turbine engine, turbofan in particular, is the compressor pressure ratio same as the overall pressure ratio? For modelling purposes can we use the same value of overall pressure ...
157 views

### Who decided that the Boeing 737 MAX planes that were airborne when the grounding was issued cannot enter and land in EU air space?

On March 12th, 2019, EASA grounded the Boeing 737 MAX series by publishing their Emergency Airworthiness Directive 2019-0051-E (AD): Effective Date: 12 March 2019, 19:00 UTC  [...] ...
49 views

### What's the theoretical background of the critical angle of attack?

The critical angle of attack seems to be at all (most?) airfoils around 15-20°. Why is that? Why is it in this range and not lower or higher? Is it just the result of optimizing airfoils? Or is it ...
176 views

### What are the “certain” flying scenarios in which the Boeing MCAS is supposed to assist pilots? [on hold]

Boeing bulletin issued last November said "MCAS provides automatic nose-down inputs to assist pilots in certain manual, flaps-up flying scenarios, especially at slow airspeeds and high AOA." ...
53 views

### Why do some airports have class E airspace to the surface only at certain times?

Below is the depiction of the Truth or Consequences airport on the VFR sectional. Notice that it states that Class E to the surface is only effective for certain hours. The Chart Supplement lists ...
106 views

### What is being depicted w.r.t. AoA in this video?

I was looking at this video of the AF447 crash simulation and at about 4:45 the angle of attack diagram shows a few things I don't understand (frame above). I get the orientation of the airplane, ...
70 views

### Which was the last Boeing crash that didn't send its black boxes back to the US?

I couldn't find an answer online, so I am asking the community. The real question is how frequent it is for a Boeing crash not to send the black boxes back to the USA, and a reply to title's question ...
10k views

### How difficult is it to simply disable/disengage the MCAS on Boeing 737 Max 8 & 9 Aircraft?

With regard to the Ethiopian crash of the 737 Max 8 aircraft, where according to preliminary reports, it appears to be related to the MCAS which is a safety system that pushes the nose down to correct ...
103 views

### Who trains 737 MAX pilots in countries outside the USA on the MCAS system? [closed]

I just read this article with quotes from a 737 Max pilot. Sounds like not enough training is being passed on to the pilots, or if it is, they aren't reacting properly. Where do non-American pilots ...
61 views

### How are rotorcraft and/or VTOL aircraft handled once they get to an airport? [duplicate]

I am asking this from an ATC perspective ... my experience as a pilot is that they would make helicopters fly the same approach but once they got the airport environment in site where do they go? Taxi ...
58 views

### What is difference between TAA and MSA?

I know the 'TAA' usually used in RNAV chart, but sometimes it can be used in ILS chart as well. (When defining an IF, GPS is solely methods) but While I'm studying, I can't find exact difference ...
506 views

### Why is it the ATC recording of Ethiopian Airlines Flight 302 is not yet available online?

I understand sites like liveatc.net constantly stream the conversation between the ATC and pilots. Why is it that there's no such recording for Ethiopian Airlines Flight 302 yet?
185 views

### Why can’t takeoff rejection be automated?

According to this comment on my previous question about automatic instrument takeoffs (or, rather, the lack thereof), the reason takeoffs are always flown manually is to allow the pilot to quickly ...
119 views

### Why does the A320 use the rudder for lateral control in mechanical law?

When the Airbus A320’s flight control system is operating in mechanical law (the simplest and lowest-tech of the A320’s flight control laws, where deflections of the pilots’ joysticks are transmitted ...
95 views

### Why don’t airliners use stabilizer movement to assist with large pitch control inputs?

Most large airliners not only have elevators for pitch control, but also moveable horizontal stabilizers. The elevators are used for primary pitch control, with the stabilizers being used to trim the ...
3k views

### Why are there 40 737 Max planes in flight when they have been grounded as not airworthy?

Many countries have already grounded 737 Max planes and as of Mar 13, 2019 the FAA have stated: The FAA is ordering the temporary grounding of Boeing 737 MAX aircraft (PDF) operated by U.S. ...
84 views

### Are the holes inside the engine nacelle used for uniform intake of air? [duplicate]

I read the post here: What is the function of the holes in splitter plates? My question is, what are those hole looking things inside the engine nacelle? It seems reasonable to me that as air enters ...
98 views

### How to literally take the wing off a single engine Beechcraft-style airplane?

First off I do not want to do any kind of maintenance. I was driving past an auto junk yard and saw they have half of a low wing, maybe a Beechcraft, airplane and I would like to try and buy the wing ...
204 views

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

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 ...
6k views

### Why do passenger jet manufacturers design their planes with stall prevention systems?

I understand why passenger jets use software that overrides pilot inputs that might cause the jet to exceed the flight envelope. But why do passenger jet manufacturers design their planes with stall ...
249 views

### Is there less vertical space for an engine under the wing of a 737 Max than for an A320neo?

The source of this question is the understanding that the LEAP-1B couldn't fit under the wing of a 737 without changing its longitudinal position. But this wasn't the case with the design of the LEAP-...
109 views

### “Report a 3 mile right base” - where is it measured from? [duplicate]

At which position should you report to ATC?
302 views

### How much of a plane is replaced over the lifetime of an aircraft?

A photo of an OC-135 with (presumably) P&W TF33-P-5 engines made me wonder how many of the components had been replaced, and what was left of the original airframe, engines, and other parts. There ...