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.


Weight is a consideration. Even when riding along in Lears, we started
off in the mid 30's. As we burned off fuel, we could efficiently climb,
in stages.. and our final cruising altitude was around 43-45,000 feet.

My PIC told me that if he tried to push the climb any harder, he simply
burned fuel at a faster rate with a poor return on the investment. I was
cabin crew, not front office, but it was still a kick listening to the
airliners trading bumpy ride reports in the FL 300's and we chime in
with smooth rides in the FL400's.. knowing they wont be able to get there.

I'm sure cabin differential is a factor as well. Higher pressurization
differentials require a more robust pressure vessel, which weighs more.
Its a trade-off at the design stage. Flying too high would raise the
cabin altitude too high, despite pressurization, and require oxygen for
the crew and or cabin.

just my 2 cents
Dave