Pressure problems...
Trying to work out what the Diff P would be for a aircraft when it is pressurised at -300ft ie The aircraft is pressurised before takeoff and landing, and I seriously can not find the PSI figure in any of the aircraft manuals that we have at work. I spent over 2 hours trying to look for something. Anyone have any mathematical idea?
for example the aircraft is flying at 20,000ft and the pressure is 7psi in the cabin.