Dan wrote in news:de91fd98-be3f-4ccb-bef2-79e2ec0dc076
@s13g2000prd.googlegroups.com:

On Jan 29, 6:03*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.

Just guessing, but perhaps the smaller cabin size handles the larger
differential pressure reqiuired better than a big cabin. The extra
expense (and weight) to reinforce a large cabin (ie. heavy jet size)
may not be worth it.

Nah, the reason the little ones can go so high is cause nobody minds if
they do!
They're not constrained by revenue considerations and can have fighter jet
type wings and other shapes to allow good buffet margins up there. You
couldn't get a 747 up that high without buffeting it out of the sky unless
it were empty and out of gas!
The pressurisation wouldn't be able for 510 in a 747 because they woulnd't
make it any tougher than they needed to.
I can't see anyone allowing a pax airplane up above 430 anytime soon for
the simple reason a rapid blowout would kill a hefty percentage of the
people on board.
Even 430 isn't going to be pretty. Anything above 350, in fact, is going to
hurt some people pretty bad.
Until a manufacturer comes up with a technology that ensures a greater
margin of safety above 430 you won't see an airliner certified above that.


Bertie