"Bob Gardner" wrote
No way. You start off at sea level, of course, and they pump the chamber
pressure down to 25000 feet with masks on...then they do some experiments
with a few of the pilots taking their masks off, just to show how severely
their abilities are affected. Then comes the explosive decompression, which
takes the chamber from 25K back down to sea level in a second or two.

Bob, what you have described is "explosive compression" not "decompression".

I would reccommend this web site to clear-up the confusion:

http://www.wvi.com/~lelandh/Alt_Chamber.htm

Bob Moore