"Ron Natalie" wrote in message
m...

"Gary Mishler" wrote in message
news:eBoKb.745162$HS4.5776347@attbi_s01...
"running with scissors" wrote
in
message om...

"they" dont. cabin pressurization is normally at 8000ft though crew
may elect to use different cabin pressures under certain circumstances

Actually, it depends on the aircraft. Aircraft are certified to certain
"differential pressures" which is the difference between in the inside
cabin
pressure and the outside ambient air pressure.

We were talking about transport aircraft. US certificated transport
aircraft
must keep the cabin altitude below 8000'.

Yup, I know. The Lear 60 is a transport category aircraft, certified under
Part 25, and it's cabin is normally around +/- 6,500ft. Previous poster
said cabin pressure is normally *at* 8,000 and I was just pointing out that
it depends on the aircraft.

Manufactures of transport category corporate jets seem to take pride in
pointing out to potential customers that their jet can maintain a lower
cabin altitude at cruise than the competitors, which all depends on the
certificated max psid.