On Tuesday, July 23, 2019 at 11:15:29 AM UTC-7, Eric Greenwell wrote:
Steve Koerner wrote on 7/23/2019 10:21 AM:
On a related note, if you run out of oxygen, you can get yourself some extra altitude margin in a pinch by pressure breathing. I rather discovered this while swimming laps. I could do better with a controlled pressurized exhale. I figured the same idea might transfer to soaring. I did some reading that supported the premise and then did some experimenting at altitude.. It definitely works (legalities aside). Having 45 years of western soaring under my belt, I have a better than average sense for my own personal oxygen requirements. My tentative conclusion is that, for me, pressure breathing is worth around three thousand feet. Certainly I'm not recommending pressure breathing in lieu of supplemental oxygen, but it might be a useful thing to know about just in case.

Are you talking about "pursed lips breathing"? That can raise my ox saturation 5
percentage points.

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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

Yes, Eric. Exhaling against pursed lips increases air pressure in your lungs during a substantial portion of the breathing cycle. Under some flying circumstances and terrain scenarios, doing so could well be a much better plan of action compared to opening the dive brakes if your oxygen fails or runs out.