Max Service ceiling for commercial airplanes

D Ramapriya wrote in
:

On Jan 30, 3:48*pm, Bertie the Bunyip wrote:
D Ramapriya wrote
innews:2690baef-0857-4600-a0c5-4
:

On Jan 30, 2:33 pm, Bertie the Bunyip wrote:
D Ramapriya wrote
innews:24252c28-895a-44da-bd25-







m:

On Jan 30, 2:08 pm, Bertie the Bunyip wrote:
D Ramapriya wrote in
news:2ff47125-cffd-4909-b028-
:

On Jan 30, 8:41 am, WingFlaps wrote:
On Jan 30, 2:03 pm, wrote:

Out of curiosity I was wondering which civilian passenger
airplanes have the highest service ceilings? Wikipedia
indicates that some business jets have ceilings greater
than 53000 ft or so while the 747 has only 43000 ft. Also
why do large aircraft fly much lower than their service
ceilings? Usually I never see a large jet go beyond 37000
or so even on very long haul flights. I assume they would
be even more efficient if they flew close to service
ceilings on long haul flights.

Could be due to weight? When you fly across the Pacific the
plane can only get higher as fuel is burned.

Get higher? I thought that's what the continual small
adjustments effected by the trim wheels do to preclude,
especially with the AutoPilot engaged?

Huh?

Bertie

I meant to say that the AP will ensure that you keep flying at
the programmed altitude (through trim and throttle changes)
instead of letting the plane go higher with diminishing weight.
Have I missed something?

We get cleared to an altitude and have to hold that altitude to
avoid running into other airplanes. The autopilot does not just go
where it pleases.

My point exactly,

No, it wasn't. you said that the AP will ensure that you keep flying
at the programmed altitude throught trim and throttle changes.
It won't.


So the AP's FD Altitude Controls do what?


The FD and the autopilot are two different things.


Bertie