Re: Cabin Depressurization

Date:         03 Mar 2000 23:25:42 
From:         JF Mezei <>
References:   1 2
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> affects of sudden loss of pressurization.  A variety of drop down masks
> were utilized in the tests. In none of the tests did the subject remain
> conscious after donning the mask. The instructor explained that above
> approximately 25,000 feet, the body will not absorb the oxygen unless it
> is supplied under pressure.

That is perhaps an overgeneralisation.

Humans have climbed Everest (8800m or about 28.6k feet) without oxygen masks.
Of course, the main difference is that the climb is gradual and the climbers
must acclimatize to the lowering pressures as they climb, something which you
can't do when a plane depressurises is a short amount of time.

At that altitude, you have about 1/3 the oxygen available, and you tend to
breathe 4 times as fast to compensate (when you're acclimatised).