Linked Questions

24 votes
6 answers
12k views

Why then don't aircraft fly even higher, for even greater efficiency? [duplicate]

After reading various superb QA on here I now see that (basically) aircraft are more efficient per passenger-mile, at higher altitudes. Why don't we go even higher, than current typical airliner ...
Fattie's user avatar
  • 1,932
4 votes
4 answers
3k views

What difference does altitude make on fuel efficiency? [duplicate]

Most commercial flights are between 29,000 and 42,000 feet in altitude apparently. But I realise I don't know why. My guesses are: If you fly too high the air pressure gets very low and you have to ...
Simd's user avatar
  • 193
6 votes
3 answers
5k views

How can flying high minimize drag and increase fuel efficiency? [duplicate]

As a plane goes higher, the engines have to work harder to compensate for the air density, therefore it will require more fuel in order to provide the same power at lower altitudes. But I always hear ...
Abdull's user avatar
  • 183
6 votes
2 answers
20k views

Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years? [duplicate]

When Boeing introduced the 747-100 in 1969, its maximum ceiling was 45,100 feet; half a century later, when Boeing introduced the 777x, its maximum ceiling was 43,100 feet. Similarly, the maximum ...
Him's user avatar
  • 5,298
4 votes
0 answers
6k views

Why do (jet) airplanes fly at tropopause (and not higher) [duplicate]

I've got a question which is nearly answered by the following thread however not fully to my satisfaction. Why do jet engines get better fuel efficiency at high altitudes? The question ultimately ...
F.B.'s user avatar
  • 41
1 vote
2 answers
3k views

What is the typical cruising altitude for a civil airplane? [duplicate]

I'd like to know the interval of altitudes airliners usually cruise at (and its reasons)? And if there are international restrictions about this? Also I read somewhere that recently about a ...
Azad's user avatar
  • 113
1 vote
2 answers
910 views

Would cone shapes grills in front of jet engines prevent damage in case of a bird strike? [duplicate]

If cone shaped grills pointing forward were in front of jet engines would they make bird parts slide outside towards the back of the engine and away?
Chris's user avatar
  • 11
0 votes
1 answer
970 views

Why do planes fly so high? [duplicate]

It so occurs to me that commercial airliners cruise at altitudes of over 30,000 feet. But why do they fly so high if there are many dangers such as cabin de-pressurization when they can simply fly ...
user avatar
2 votes
2 answers
675 views

Could an airliner get better fuel efficiency at higher altitude? [duplicate]

By higher I mean like 60k feet instead of 30k. Seems like the rate limiting step is engine performance at 60k feet. Are people working engines that can operate at higher altitudes? How close are we ...
Dale's user avatar
  • 201
1 vote
0 answers
255 views

Why airliners fly so high even when winds are more suitable at a lower altitude? [duplicate]

While playing a flight sim, I noticed West winds were very strong at levels >FL350 and weaker around FL270 above the US. I took a look at Flight Radar 24 to see at which level actual airliners were ...
Nicolas's user avatar
  • 11
1 vote
0 answers
48 views

How is a design cruise altitude picked? [duplicate]

Different planes have different design cruise altitudes, given by the manufacturer. You can find these in their Airport Planning Manuals or in Jane's All the World's Aircraft. I know that the first ...
stevederekson555's user avatar
69 votes
10 answers
94k views

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 ...
Jae Carr's user avatar
  • 24.2k
67 votes
5 answers
43k views

What determines the maximum altitude a plane can reach?

What factors determine the maximum altitude for a plane? Is it limited by wing design, engine thrust, and so on? Is there a formula by which one can calculate the maximum altitude a plane can reach?
Vido's user avatar
  • 761
71 votes
3 answers
18k views

Are we at peak speed efficiency for jet airliners at Mach 0.85?

The cruising speed of large jet airliners has not increased in the past four decades. The 747 cruised at Mach 0.85 and the new Dreamliner 787 also cruises at Mach 0.85 even though it was designed 40 ...
RoboKaren's user avatar
  • 8,071
39 votes
4 answers
24k views

Why do private jets such as Gulfstream fly higher than other civilian jets?

I heard in a TV show that private jets such as Gulfstream can fly at about 50,000 ft, higher than other civil jets. Is it an aerodynamic reason (lighter aircraft to be sustained in a less dense air) ...
Luca Detomi's user avatar
  • 1,992

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