Scared Silly
Contributor
This is not exactly correct. I have experience in climbing and had certification as a wilderness 1st responder to identify and treat accidents and illness while climbing. 14,000 ft results I'm mild altitude sickness. Likely symptoms are a headache and possible swelling. Around 20,000 ft is where things start to really change. Many people each year leave sea level, fly to the mountains and ride a ski lift to over 10,000 ft. The majority may have some shortness of breath with exercise, that's about it. Some will show very minor altitude sickness (headache). There is plenty of oxygen in the air at those altitudes. We use very little of the oxygen we breath, that's why CPR works.
We are getting OT here and splitting a lot of hairs, but with all things related to breathing, it is not the amount of O2 that matters but the PO2. Around here (Oootah) we have a term called a Texas heart attack for those who come from sea level, ski a few runs, experience a shortness of breath, and other symptoms of AMS then go to the clinic thinking they are dying. They are told to go down in altitude, not to drink alcohol, and rest for a day to acclimate.
To compare aviation functional requirements to that of skiing/climbing is apples to oranges. The requirement for aviators to O2 use at 10k is to prevent any chance of AMS. It does not mater that only a few people in the general population may exhibit mild signs of AMS and be functional. The requirement for a pilot is not to have any regardless, as one does want to have any signs/symptoms of AMS while flying a airplane. Period.