This might be totally OT, but the reason why airliner service ceilings are
often below bizjet ceilings is actually really boring: oxygen requirements.
Aircraft are required to be able to generate sufficient passenger operation to
for the entire descent down to a prescribed series of altitudes in case of
depressurization. To fly higher you need to either descend faster or carry
bigger oxygen generators.
I used to fly an aircraft that had one ceiling as an airliner, and a different,
higher ceiling when certified as bizjet. The bizjet configuration simply had a
different passenger O2 system.
Often the other system is a variable too - if the speed brakes are inop, you
are often restricted to a lower max altitude.
Kevin
On Mar 1, 2021, at 4:42 PM, Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
On Mon, 1 Mar 2021, roxanna Mason wrote:
The point is 40KFt is at commercial jet altitudes and some business jets
like the Lear 24 service ceiling is 51KFt.
Indeed, if memory serves, a 747SP -- the specialist long-haul 747 derivative,
same wing and engines but shortened fuselage -- could be up near 50k at the
end of a long flight. (They ended up needing to add ozone filters in the
cabin air inflow, because up there at the edge of the stratosphere, the ozone
concentration in the incoming air was starting to become noticeable.)
Henry