"Bucky" wrote in message
oups.com...
So you're saying that the engines could operate at an even higher
altitude. It's just that the cabin pressure could not be maintained?

It really just depends on the aircraft. Every airplane has a variety of
limits with respect to their operation. For many of those limits, there are
actually a variety of potential limiting factors resulting in those limits,
with usually only one being the *actual* limiting factor.

For a pressurized aircraft, the certified ceiling could be due to the
pressurization system or due to some engine limitations, or due to something
else entirely (like stall speed, for example, where "stall" refers to an
aerodynamic limitation having nothing to do with the engines). You'd have
to consult the aircraft designer to learn which it was.

Pete