A query about cabin pressurisation....
One thing struck my attention while on an airline flight recently.
I know that the cabin pressure during flight is reduced to the equivalent of about 8000 feet. Therefore a passenger should feel a change in cabin pressure as the plane climbs up to 8000 feet. Theoretically, passed this altitude, he should feel no more changes because the cabin is then held at this pressure for the rest of the climb. However, I noticed that as the plane started its descent from 37000 feet, I immediately felt my ears popping, even though the pressure shouldn't have changed until we passed back through 8000 feet. Can somebody explain this to me?
Another point about this - I took eight flights in the last week and noticed that it didn't happen every time - some times my ears barely popped at all, other times it felt quite sore. Has this anything to do with the regional QNH?
If it's any help, this effect was greatest in the DC-9s. I also flew A-321, B777, and B717.