At 08:33 AM 9/28/03 -0400, adam wrote:

>>>>>>If you have an engine failure isn't it true that you no longer have cabin
pressurization?  Would you anticipate going on emergency oxygen in this
situation or do you just attempt to get down to 10,000 or 12,000 before you
black out?

scot
+++++++++++++++++++++++++++++++++++++++++++++++
>>>>>Posted for "Tom Hall" <tomhall@starband.net>:

Unless you are a serious smoker or otherwise quite impaired in your
pulmonary function, you will have no problems remaining consious and
performing once you get below 20k. Give it a try sometime. You will find
that while you may notice some vision acuity decrease and your mental
functioning may be slightly less acute, you certainly can survive.
(especially if your adrenaline is pumping after a engine failure!!)
 
>>>>>>>>>>>>>>>>>>>Scot....honestly I wasn't thinking about emergency Ox...gotta remember don't have that in the little four-bangers;)   Yes, I would emergency oxygen.  I found this table of "Times of Useful Consciousness" <after losing pressurization> on the USAF flight surgeon guide...>
 
FL 180 20 to 30 Min
FL 220 10 Min
FL 250  3 to 5 Min
FL 280 2.5 to 3 Min
 
Two things to note are that these are "average" times and also that they are not to total incapacitation.

Yes, AVERAGE means just that.  If you do not know YOUR time to unconsciousness, you should invest in a "high-altitude training course." 
Paul and I did one in San Antonio, and while we did fine, our CFII (who was retaking it to see if he had any "warning signs" of incapacitation) passed out within a minute of depressurization.  That is AFAIK the way he always reacts.  He knew he would pass out, and wanted to know if he would have any warning signs that would signal he would need oxygen.  Since he doesn't seem to detect them, he would of necessity have to grab the O2 immediately on depressurization.  Although HE did not smoke, his wife did.  I do not know how much this affected him in that regard.  Both he and his wife now fly for major airlines.  Time to unconscious is a VERY individual thing.  Paul got "silly" after a couple of minutes, but I was still answering questions (correctly) on the test they give you to keep checking your awareness when my fingernails and lips were quite blue.  Paul (already back on O2) motioned to me to look at my nails, and I realized then that should put the O2 and mask on, too.

Bottom line, if you don't KNOW you can make it all the way down and still be conscious, grab the O2 FIRST.  Then you can be reasonably sure of knowing you're doing the right things to fly the airplane and restart the engine.   Didn't someone say that the best glide was about 400ft/min?  If so, then the time to get down to breathable air from FL260 is WAY to long to try to go without oxygen.

Here's hoping none of us ever have to worry about that!

Vickie Davis
Legacy 124

--
Vickie B. Davis, Ph. D.
vdavis@ieee.org