How High

pm.

Just a quick question, how high could a passenger jet fly something like a 737 or a A320. What would happen if they went higher that the guidelines?

Stovepipe

airliners are always under positive ATC control and have to stay at assigned heights; a 737 or an A320 could get to the likes of 41,000 feet but routinely operate at lower levels in the mid-30s for fuel efficiency.

pm.

What would happen if they went higher than that? Just out of curiosity

Pat Dunne

pm. wrote: »

What would happen if they went higher than that? Just out of curiosity

It might get stuck up there and not be able to come down again.

Henry Ford III

pm. wrote: »

What would happen if they went higher than that? Just out of curiosity

Simply it can't.

https://en.wikipedia.org/wiki/Ceiling_(aeronautics)

Irish Steve

It ends up in what's known as coffin corner, where the stall speed and the achievable air speed coincide, (due to the air becoming thinner at high altitudes) at which point, life for the crew becomes "interesting", in that you can get overspeed AND stall warnings at the same time, and avoiding damage to the airframe requires some very delicate handling. If the control inputs are too aggressive, significant airframe damage can occur.

pm.

Henry Ford III wrote: »

Simply it can't.

https://en.wikipedia.org/wiki/Ceiling_(aeronautics)

Thanks that explains it..

Alun

Isn't there one of these new experimental space planes that's launched from atop an adapted commercial airliner? I'm guessing that flies as high as is practically possible to gain as much advantage as possible?

veetwin

I recall being on an almost empty chartered 767 when the captain got on the PA to announce the we were cruising at FL 43. He was quite chuffed about it at the time!

martinsvi

another consideration is the jet engine itself and air conditioning system. If a plane/engine is designed to operate at certain altitude, it relies on certain amount of oxygen being available for efficient combustion and feeding the cabin with air. If you go too high, not only the wings will have no grip, the engines might surge/stall as well and cabin might loose oxygen level

the experimental space or near space planes (Virgin Galactic, SR-71 etc) typically use some sort of Delta wing or fuselage design which allows them to achieve greater altitudes and speeds. However this design is impractical for passenger jets because at low speeds and altitudes (approach to land for example) it requires high angle of attack to maintain lift and also can be fairly unstable - part of the reason why Concorde typically had to add some 25 - 40kt on take-off and landing speeds comparing to similar sized airliners

another thing which Virgin Galactic or SR-71 can do but regular planes can't - is to use the afterburner. Typically this causes quite a bit of noise which folks on the ground are not too excited about.

Henry Ford III

I remember at extreme altitude the U2 had a tiny window of speed, and that it was perilously close to stalling.

Jawgap

Yeager took an NF-104 on a rocket assisted jaunt to just shy of 120,000ft.....it didn't end well - stalled, flamed out, he couldn't re-start he spun down through over 100,000 ft and finally punched out at about 12,000ft only to get the ejection seat 'ass kicker' rocket motor in his face!!

The dramatised version.....

https://www.youtube.com/watch?v=q3BMg99K_o0

maximum12

Two idiots tried it on a ferry flight along with some other joy riding maneuvers that got them killed

https://en.m.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701