**Jetlagged**
Normal max diff pressure on a B747-400 is 8.60 psi, which at

FL 370 would give a cabin altitude of around 6,000 ft, so, as you suggested, it appears there is a typo in the figures posted by

**PhilSquares**.

Interestingly however, the typo need not be the cabin altitude, as one might at first glance assume, but is probably in the aircraft altitude, and, just possibly, in the quoted max diff figure.

Substituting a

*2* for a

*7* in the quoted altitude (thus FL3

*2*0 not FL3

*7*0) makes the figures correct:

Max differential pressure......8.60 psi

Ambient pressure FL320......3.98 psi

Cabin pressure at FL320....12.58 psi

Cabin altitude at FL3

*2*0.......4,300 ft

It is also, just, possible that they were operating at the

**limiting** max diff of 9.4 psi on the B747-400 (

*can’t think why you would, but never mind*) which would again make the figures correct:

Max differential pressure......9.40 psi

Ambient pressure FL370......3.15 psi

Cabin pressure at FL370....12.55 psi

Cabin altitude at FL370........4,300 ft

However, my best guess is that our friend simply typed FL370 instead of FL320.

Regards

Bellerophon