If you have the auto controller set at sea level then you would maintain a cabin at or near sea level until 22,000 feet aircraft altitude, probably near max differential pressure also
.
If the aircraft climbs say to 31,000 feet with the auto controller still set at sea level then the cabin would climb and try to maintain a max differential pressure.
If the max diff pressure is exceeded then the relief valves would open.
Red faced item! LOL
Dont remember the actual numbers since going back to the 747.
Normally the cruise level is set prior to takeoff on the scale and cabin climbs to the preset level at whatever rate you have selected.
Same situation on decent, if you were to forget and leave the cabin altitude at the cruise flight level then the controller would maintain this until max diff pressure was met and then start descending the cabin.
Little hard on the ears as the rate of decent for the cabin would match the aircraft depending on the situation.
Last edited by Earl; 20th April 2008 at 03:04.