wrote:

I just got off the phone with Southwest Customer Relations asking a
question about cabin air pressure. Two separate people informed that
cabin air pressure in flight is 14.7 psi (sea level equiv.) and that it
is 10.0 psi (about 10,000 ft equiv.) on the ground.

Obviously, this has to be backwards, right? Even so, don't regulations
require cabin air pressure to be between 5,000 and 8,000 equiv.
altitude?

My understanding is that the pressure altitude in the cabin is to be
kept at 8000' or below. I've monitored the pressure altitude on quite
a few flights on various airlines and have noticed quite a bit of
variation. Some flights were kept very close to the 8000' limit
(around 7900'), while the lowest I've seen while at cruising
altitude was around 5500'.

Wouldn't that mean one of the numbers they gave me would
have to be between 12.23 psi (5,000) and around 11.0 psi (8,000)?

The reason I ask is rather important. My friend has a heart condition
and needs pressure of 4,000 ft or less. Southwest does not allow
supplemental oxygen, and he'd rather not use it anyway. The numbers
they give out seem suspect, and I can't take chances here.

Unless special arrangements are made for the flight it would almost
certainly exceed an equivalent pressure altitude of 4000'.