Posted for "Stuart Seffern" <sseffern@yahoo.com>:

 Hi Steve,
 
 Also check out a pulse oximeter to check your O2 level as you fly.  Don't let
it drop much below 90.  I've flown at FL22 for over 1 hour in a O-360 powered
lnc2 over very bad wx with supplemental O2.  You can also pressure breathe for
a short period to avoid Hypoxia temporarily.  The AF still does a High
Altitude training school for civilians so you can recognize the signs and
begin to determine your tolerance.  The price is very reasonable last time I
did it at Dayton's Wright Patterson Field.
 
 Regards,
 
 Stu Seffern
 sseffern@yahoo.com