Passing out at high altitudes / the Greek ailrliner crash

Based on my experience in a USAF altitude chamber, after the chamber has
been pumped up (actually down...it is a vacuum) to 25000 feet and the
pressure suddenly dumped as would be the case in a decompression, whatever
air you have in your lungs comes out forcefully...no way do you have any
control over it. Gotta get that mask on and get it on in a hurry, because
time is fleetingly short.

In US regulations, the magic altitude is flight level 350 (more or less
35000 feet, depending on ambient atmospheric pressure). The Cypriot plane
was reportedly at FL 340, if we can believe the media. Under US rules, above
FL 350 both pilots must be at the controls and each must have a
quick-donning mask at hand. If one pilot has to leave the cockpit for any
reason, the other has to put on and use oxygen until he returns.

Lots of unknowns.

Bob Gardner


Bob Gardner

wrote in message
oups.com...
I am not a pilot, and as much as my email address sounds like I am a
doctor, I'm not...

That said, I thought someone here might be able to help me out - they
news reports talk about passing out within seconds at high altitudes.
I understand the air is thinner / less O2.

But if I go underwater, there's certainly no air there. And I can stay
down for a while, holding my breath. How is high altitudes different?
I would think you would rasp / fight to breath in but keep functioning
as your body uses up the 02 in the blood from your last breath? Not
like a sleeping gas in the movies where you just keel over as soon as
it hits you?

THANKS!