Re: Cabin Depressurization

Date:         06 Jan 2000 01:26:10 
From:         glpilotsrv@aol.com (GLPILOTSRV)
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In article <airliners.1999.1301@ohare.Chicago.COM>, "P. Wezeman"
<pwezeman@blue.weeg.uiowa.edu> writes:

>The author also stated that emergency oxygen systems
>on airliners had never saved a single life. Is this true? Any
>counterexamples? I know of at least three explosive decompressions
>where most of the passengers survived: the DC-10 where the cargo
>door blew out over Canada, the Aloha Air 737 where the top of the
>forward fuselage came off, and the 747 that lost a cargo door
>over the Pacific. Did oxygen systems help in any of these cases?

I would not doubt the statement. Drop down oxygen systems do not supply
oxygen under pressure. Above approximately 25,000 feet, oxygen needs to
be supplied under pressure, otherwise the hemoglobin will not absorb the
oxygen present.

The flight crews will have quick donning masks that will supply the
oxygen under pressure. The mask will actually inflate the lungs and the
user will have to forcibly exhale.

It was noted at the High Altitude and Flight Physiology training at ADW,
that unless the crew already was using oxygen, the best outcome of an
explosive decompression at high altitudes (35,000 feet+) would be the
crew would gray out during the process of donning the masks. Of course,
the worst outcome is the crew taking longer than the few seconds of
useful consciousness they have to don the masks and blacking out.

This is the reason that above 25,000 feet, if one crew member leaves the
flight deck, the remaining crew member is required to use supplemental
oxygen. Above 35,000 feet, regardless of number of crew members on the
flight deck, one crew member must utilize supplemental oxygen.

If you are on an aircraft when the overhead masks deploy, go ahead and
quickly pull the mask fully down (this starts the oxygen flow) and place
the mask over your nose and mouth. If this occurs at high altitude, just
plan on waking up with a slight headache after the crew has completed
the emergency descent.

Garrr