Questions tagged [airliner]

An airliner is a large, commercial aircraft operated by an airline for transporting people and/or cargo.

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Why do jet engines get better fuel efficiency at high altitudes?

I'm told that this is true, but I can't imagine why. It seems like the fact that there is less air would make the engines less efficient... But that probably just shows how little I know about jet ...
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41 votes
11 answers
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Could an electric engine provide the same performance as jet engines on current aircraft?

I have looked at various questions on this SE site regarding this topic but I have not really found a satisfactory answer. Some comments here regarding torque and power in electric motors vs gasoline ...
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30 votes
3 answers
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Why are propeller engines uncommon on airliners?

My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range. I assume that turboprop engines are more fuel ...
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66 votes
3 answers
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What is the purpose of the sharp pods under airliner wings?

What are the pods with the sharp trailing edges underneath the wings of large airliners, as shown in the image below? My best guess would be fuel tanks
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46 votes
5 answers
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How do airliners get from the factory to the client if the aircraft does not have the required range?

Today I flew on an Embraer 190 of Kenya Airways. Checking in the tech specs this aircraft has a range of roughly 2900 km. Considering it is built in Brasil, I was wondering how do they deliver it to ...
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46 votes
3 answers
66k views

Are cargo holds pressurised these days?

This question is only regarding aircraft that seat more than about 100 people. Are cargo holds pressurised these days, what is the situation? Are only some pressurized, most, of every single one? ...
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24 votes
3 answers
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What does it take to turn a 747 around 180 degrees?

Assume that a 747 is flying at cruising altitude and speed. If the pilot decided (for a presumably good reason), to turn the plane 180 degrees, How quickly could the turn be completed? How wide would ...
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29 votes
6 answers
16k views

For large jets, what is the primary means of slowing down after landing?

I understand that a large(r) commercial jet slows down after landing using the following methods: Wheel brakes Reverse thrust Spoilers/flaps/airbrakes What is the effectiveness of each compared to ...
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59 votes
9 answers
47k views

Why not mount airliner jet engines above the wings?

It seems that most airliners put the engines below the wings, i.e. the Boeing 7*7 series and the Airbus A3** series. This requires long (heavy) landing gear, and the engines are close to the ground ...
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12 votes
2 answers
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How does the raked wingtip of the Boeing 787 work?

The wing tips are very different on these airplanes. The wingtip on a Boeing 787 is a sharp triangle, while the wingtip on a Boeing 737-300 is flat. British Airways Boeing 787-8 G-ZBJC wingtip | by ...
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19 votes
1 answer
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What are these antenna-like protrusions for on an airliner?

This is a JetBlue A320: I've always wondered what these are for, but could never find the answer. I'm guessing a few of them are for receiving information from satellites.
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104 votes
15 answers
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Why are planes generally painted white?

When planes come off the assembly line at the factory, they're green: So why are most painted white? Surely a darker colour would hide dirt better? Is there a reason planes are traditionally white? ...
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72 votes
6 answers
28k views

Why are fuel tanks in the wings filled first, and why are they used last?

When fueling airliners, why is fuel filled first in the tanks in the wings and then the center tanks? And why do they use fuel from the center tanks first and then from the tanks in the wings? From ...
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28 votes
2 answers
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What is the typical temperature of an airliner's hull during flight?

Some high-speed military aircraft like the SR-71 had real heating problems, but airliners also travel almost at the speed of sound, use most of their fuel to make up for frictional losses, so I would ...
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29 votes
2 answers
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How much of an improvement would a 1% weight decrease on an airplane be to the industry?

Say I thought of a very easy and inexpensive way to reduce the takeoff weight of a commercial airplane (body, fuel and passengers) by 1%. How much would this mean to the industry? Would it make much ...
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27 votes
6 answers
19k views

Can large airliners do aerobatics such as loops?

This subject has been partially covered before here Is it possible to do a barrel roll in a large aircraft like a B737? and here Is it safe to roll an airplane that isn't approved for it? If a ...
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36 votes
4 answers
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Would failure to put on an oxygen mask during loss of cabin pressure result in death?

I was trying to explain to someone why the cabin is pressurized (no one wants hypoxia) and that led to discussion about the emergency oxygen masks available on airliners. If a person didn't put on ...
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24 votes
6 answers
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Can passenger movement in an airliner make it stall?

This question shows a couple of air hostesses dancing during mid-flight and the co-pilot came out of the cabin to record it. This made me wonder: Can flight crew or passengers moving around in ...
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59 votes
3 answers
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What are these things hanging off the trailing edge of the wing?

What are these things hanging off the trailing edge of the wing? I've seen them in almost all of the aircraft I've flown in, and can't remember if they're exclusively Boeing or Airbus.
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29 votes
5 answers
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Why do we use pylons to mount the engines on jetliners?

This question focus on jet airliners. The De Havilland Comet's engine were mounted inside the wing, the Concorde's engines were mounted underwing (as many jet engines) but without pylon. It seems jet ...
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33 votes
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Why do we never see high-bypass turbofan engines sharing the same nacelle on large airliners and similar aircraft?

I'm talking about this sort of thing (this is the fictional airplane from Casino Royale), rather than two (or more) engines per wing in individual nacelles: If we ignore the weird 'drop tanks' on the ...
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8 votes
3 answers
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What is the difference between Assumed Temperature and Derate takeoff thrust?

Airlines like to avoid a full thrust takeoff as it increases the wear on the engine. There are two methods to achieve this: Assumed Temperature and Derate. In the Assumed Temperature method, the ...
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39 votes
8 answers
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Why don't airlines load their passengers like freight?

Apparently, the time for boarding and deboarding an airplane is a large cost factor and something airlines try to minimize but have trouble controlling because the passengers do it themselves. A ...
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19 votes
3 answers
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Why is the Tu-144 the only commercial airplane with canard configuration?

I understand the delta wing was chosen because of the supersonic cruise (like the Concorde), and canards were added to reduce the approach/landing speed. But canards may be used without delta wing (e....
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9 votes
1 answer
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How is bleed air used to start a jet engine?

I know that most jet engines on commercial jets are started either with bleed air from an APU or bleed air from the other engine... But I'm not exactly sure how bleed air actually starts the engine? ...
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33 votes
6 answers
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Why do airliners pitch up during cruise?

In my experience as a passenger, when the plane stands at the airport and you enter it, the aisle is pretty much horizontal. (Obviously, I've never flown on a DC-3). After takeoff we pitch sharply ...
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16 votes
2 answers
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What exactly are those openings in the bellies of many jetliners?

I have circled the areas (in yellow) under the belly of the 737. What exactly are those? (airliners.net)
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6 votes
2 answers
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How much fuel is used for the different phases of the flight of a typical airliner?

An Airliner flies from LA to JFK in 5 hours. In the first 30 minutes the plane climbs to about 30,000ft. For the next 4 hours the plane flies at about 30,000ft. For the next 30 minutes the plane ...
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80 votes
8 answers
19k views

Why do aircraft models end their life as freighters?

There seems to be a tendency that aircraft models are more long-lived for cargo than for passenger service. For example, both the A300 and MD-11 are all but extinct in scheduled passenger service, ...
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13 votes
3 answers
4k views

Why don't airliners carry radar jamming technology or missile counter measures?

Why is it that commercial passenger aircraft that fly through dangerous areas don't carry some sort of electronic counter measure to defend themselves from missiles? Between terrorism and the various ...
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36 votes
12 answers
16k views

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

A car can be towed by a tow truck to the repair shop when it breaks down on the highway. Is it possible for a passenger plane to be towed by an emergency tow plane along the air corridor to the next ...
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28 votes
3 answers
29k views

Where does my pee go when I flush at 35,000 ft?

One thing I guess a lot of people wonder is: what happens you flush the toilet in an aeroplane? Does it fall out the belly of the plane and disintegrate? :) A kiwi woman complains that "aeroplanes ...
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9 votes
2 answers
3k views

How much air is recirculated (vs. bleed air injected) in modern airliners cabin?

Air in the cabin of airliners is a mix between: new air (engine bleed air or ram air in some aircraft) and recycled air pumped out of the cabin, filtered and re-injected. How much air is ...
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40 votes
6 answers
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What's the point in escorting a threatened flight with two fighter jets?

Two days ago I read in the news: Two U.S. fighter jets escorted a Canada-to-Panama flight back to Toronto after a passenger allegedly threatened the plane Friday morning. The nature of the ...
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34 votes
7 answers
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Why are jet aircraft never designed with a slower cruise speed?

All jet airliners have a cruise speed between Mach 0.82 and Mach 0.85. At those speeds the aircraft are flying at their maximum subsonic speed. Any greater cruise speed would only be ...
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33 votes
1 answer
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Why is there a hole in one of the layer of an airplane's windows?

On a commercial airliner, there is a hole in one of the layer of the passenger windows. See here: and here: Or in more detail: Can you explain the physical reasons for this design choice?
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33 votes
6 answers
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If a typical passenger plane had total failure of all engines mid-flight, is it possible for passengers to survive?

I have pretty bad flying phobia and often wonder what would happen if all the engines on the craft went out at the same time. I initially had the anxiety-ridden thought that the hundreds of thousands ...
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27 votes
4 answers
42k views

What is the typical touchdown vertical speed of a large airliner?

What is the vertical speed (range) of a Boeing 787 (or any other large commercial aircraft) that should be achieved just before and during touchdown? I'm not interested in the vertical speed during ...
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23 votes
5 answers
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Is spin recovery possible in an airliner?

During initial flight training a lot of emphasis is placed on stalls and spins and how to recover from them, but is it possible to recover from a fully developed spin in an airliner? Do these large ...
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13 votes
1 answer
2k views

What are the design parameters for airliner safety?

Airliners designed to carry multiple airfare paying passengers are regulated by CFR 14 Part 25, and by EASA CS-25. The design regulations are such that the probability of a catastrophic failure with ...
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9 votes
1 answer
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Are there any fly-by-wire airliners with negative or near-neutral pitch stability?

Are any modern commercial airliners with fly-by-wire flight control systems designed with negative or near-neutral pitch stability so that they can take advantage of the capability of such systems to ...
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25 votes
4 answers
5k views

Why are heavy flaps better than just a bigger wing?

Flaps increase lift during landing and T/O. But when retracted, they do nothing. The space needed to stow the common fowler flaps can't be used for anything else - fuel or structure. Extended flaps ...
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17 votes
1 answer
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What happens if a passenger dies mid-flight?

Last month (December 2014), there were news that a passenger passed away during a flight. As mentioned in this answer, it appears that it is not a very uncommon scenario. In an unfortunate incident ...
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8 votes
3 answers
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Why are airliner cockpits not shielded from lasers?

With the recent increase in laser incidents reported by pilots, why don't airliner manufacturers shield airliner cockpit glass from lasers? The Abrams tank is shielded, protecting the crew from ...
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30 votes
6 answers
5k views

Why isn't the wing span of a certain airliner longer with the longer fuselage versions?

The Boeing 737 next generation models (700,800,900ER) all have the same wingspan at 117ft 5 in. Why doesn't the wingspan increase with bigger and longer models? With the 737-900 wouldn't you need a ...
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29 votes
10 answers
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Can a plane fly without the vertical stabilizer?

What would happen if a plane (for the sake of the question let's say that the plane is an Airbus A380) lost its vertical stabilizer? https://commons.wikimedia.org/wiki/File:...
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35 votes
3 answers
22k views

Why don't airliners use in-air refueling systems?

Right now if an airliner wants to fly a really long distance (eg., a Boeing 787 flying from Seattle to Tokyo), it has to load itself down with lots and lots of fuel, which in turn weighs thousands and ...
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25 votes
6 answers
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What are the factors behind increasing aircraft window sizes?

Modern airliners like the Airbus A380 and Boeing 787 have bigger windows than older designs, like the Boeing 737 and Airbus A320. What factors have led to this change of window size, opposite to the ...
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20 votes
2 answers
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What are these lines on the nose of a Boeing 737?

What are these lines on the radome? You can also see them here: What are they and what is their function? Source: AviaFilms
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18 votes
5 answers
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Are there non-economic barriers to a 1000 passenger aircraft?

I know the number 1000 is just an arbitrary number that happens to have some zeros in it, but is there any non-economic obstacle to making a 1000 passenger aircraft? Also, assume normal-ish space-per-...
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