And I hope that doctor knows about airline 02 masks, flight crew type and cabin type masks
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And after being briefed as to how they work, he will tell you something to the effect that, indeed cockpit flight crew masks are somewhat adequate for use up to about 32-33,000 feet... if well sealed on the face. He will certainly recommend not to rely on them for any extended amount of time above, shall I say about 25,000 feet. These are not "pressure type" 02 masks.
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And bad news for the cabin type masks, for passengers. The comments of "Eat My Shorts" are no far from the sad truth. Again, these are rubber cups which do not fit well, leak a lot of 02, and the 02 is just a free flow, without pressure. I would say (military pilot aeromedical pressure chamber training) that they help sustain life at a cabin altitude of maybe 14 or 15,000 feet.
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Loss of cabin pressure, yes, an emergency descent is necessary. No doubt about it. Get to these lower 15,000 to 20,000 feet ASAP. Then, hope for the best. If healthy, most people will be ok... hopefully.
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The 10,000 feet is an arbitrary figure... In the FAA, CAA and JAR books.
Maybe other books.
I doubt it means anything to people who live all their life at 10,000 feet in Quito, Ecuador. You and I feel tired when on layover, in Quito, or even only in Bogota's 7,000 feet MSL... And how about of the people living around La Paz in Bolivia at 13,500 feet elevation, maybe with a QNH of 950 mB at times.
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With PanAm, if we had to operate in La Paz, we would have been required to use our masks at all times on the ground. The guys with LAB or Ecuatoriana dont do that (they probably are healthier, munching their coca leaves).
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As to descending to 10,000 feet for your emergency descent, fine and dandy if you are over the Netherlands or Ireland... Watch-out going from Argentina to Chile... The summits are at 24,000 feet. The 10,000 feet rule is the common denominator for most people, yet most of us, healthy pilots, with a Class 1 JAR medical can live perfectly at 14,000 feet. Just very tired if we party and booze a lot... or smoke.
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I crossed the Andes with my little plane, a L-21 Super Cub, from Mendoza, Argentina, to Santiago, Chile, a few years ago (the most scenic flight experience ever of my life). I had an oxygen bottle and mask (remembering the 10,000 feet rule) and had to negotiate a mountain pass at 14,000 feet.
The 02 bottle was there... I have to admit that I did not use it.
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Passenger masks are next to be worthless... that is what I know...
And however excellent JAR training standards are, and your MCCs, and your modular courses or frozen ATPLs might be, I would personally recommend to forget all that and require pressure chamber training for any crewmember who flies an aircraft certificated for operations above FL 250.
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Oh, by the way, in airlines, we keep the cabin altitude generally around 7 or 7,500 feet.
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Happy contrails