Re: Cabin Depressurization

Date:         10 Feb 2000 05:03:28 
From:         "Chris Dahler" <>
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> >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.

Right rule, wrong altitude.  One crewmember has to use supplemental oxygen
at all times when the flight is above 41,000.

> I presume this is an FAA rule.  I have been in the cockpit a number of times
> on British registered aircraft when the plane and crew have met either or
> both these criteria, and have never seen the oxygen mask in use.  In fact
> I have never seen it available - i.e. sitting next to the seat which makes
> me wonder just how quickly it could be put on.

I don't know about British rules compared to FAA rules.  I can say that in
everyday practice, the reality is that very few crewmembers will actually
put the mask on when the other pilot heads to the restroom.  Unless, of
course, the FAA is on board!

As to the location, most O2 masks in the cockpits of modern airliners are
flush-mounted in a little compartment somewhere near the pilot's knee.  The
next time you are in the cockpit, look around near the jumpseat, and you'll
see a little greenish hose that seems to loop out and in a compartment that
has two red tabs sticking out of it.  If you pinch both of those two red
tabs together and pull, you'll hear a loud hiss as the two flaps of the
compartment pop open and you realize you are holding the O2 mask.  As an
extra bonus, you get to spend the next 15 minutes trying to figure out how
in the world to get the mask back in that compartment and how to get those
two flaps closed!

The action of grabbing the mask and putting it on really takes no more than
2 or 3 seconds.