Re: Oxygen

Date:         12 May 99 02:48:54 
From:         "R W Walker" <>
Organization: Skywalker Pangalactic Holdings
References:   1
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timma <> wrote in article
> Can anyone tell me how we survive breathing oxygen above 12K in aircraft
> without oxygen masks??

Two ways:
1. Oxygen doesn't stop at 12,000 ft. It gets thinner (lower partial
pressure) with altitude, gradually from sea level up. The human body can,
to some extent, get used to operating with less oxygen, particularly if
given enough time. After all, there are people in South America and Asia
who live all their lives at 10,000 feet or higher.

The effect of oxygen loss is gradual, so most people can briefly be fully
functional above 12,000 ft without extra oxygen (speaking from personal
experience here).

2. (But you probably already knew this). In a pressurized airplane, the air
in the cabin is at a higher pressure, as in the atmosphere at lower
altitudes. Typically, commercial aircraft cabins rarely exceed an 8,000 ft
pressure altitude. Pressure altitude means the air pressure is the same as
outside air at this height.