Rob -

My recollection is that it is not linear and generally follows the pressure map
of the atmosphere. It also varies a bit with ones's physical condition and basic
physiology. Paine Stewart and his crew were flying above 40,000 ft and the TUC
is measured in seconds up there. Any cabin altitude above about 33,000 would get
you automatic pressure breathing from the regulator in fighters. Perhaps someone
on this net has an Air Force training manual that they could copy the TUC chart
for your. Allen Konkel are you lurking on this net?

Cheers,

John


2/9/2003 10:54:10 AM, "Rob Logan" <Rob@Logan.com> wrote:

>> (TUC) ..is.. 20-30 minutes at 18000', 3-5 minutes at 25000'
>> I think anyone flying w/o O2 willingly above 12500 is really asking for
disaster

>is TUC linear or exponential?