Tango Eight wrote on 7/23/2019 8:57 AM:
The smart guys are on O2 at 10,000 during the day and 5,000 at night. Most humans are measurably impaired at 12,500.

I might be even smarter: last year, I began using oxygen above 8000', when I
discovered I began a form of periodic breathing at about 8500'. It's easy to
detect with an oximeter, which showed my oxygen saturation varying between 95 and
90 over a 1 to 2 minute period. With my EDS turned on, I stay in the 96-97 range.

The periodic breathing is fairly common, I've read, among pilots and mountain
climbers. Another reason to carry and use an oximeter.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf