Is there any industry (or regulatory) standard for emergency descents? I thought the article I read on the Chinese incident said that a descent of 25,000 feet in ten minutes was the standard for an emergency descent following cabin depressurization. The Ryanair flight descended more than twice as fast as the Chinese aircraft.
How long is the emergency oxygen supply good for, anyway? And how low does the plane have to get? IIRC, modern aircraft are pressurized to something like 12,000 or 14,000 feet. I know I've been at the summit of Pike's Peak, which is a bit over 14,000 feet, and I didn't need oxygen. I wasn't going to be running any marathons at that altitude, but I wasn't suffering hypoxia, either.