Hypoxia in the Owens Penguin thought that y'all might find some value in an off-line discussion we've been having about hypoxia. I used to fly for years without O2. I got hypoxic so many times that I now know the warning signs for my body very well. These vary from individual to individual.
Some people get spacey, some get headaches, etc.
For me, it is slight hyperventilation followed by a distinctive warm tingling feeling in the upper halves of my ears. Now, as soon as my ears get warm and tingle, I stuff the bar and dive down to at least 12k. That stops the tingling and the hyperventialtion. After 5-10 minutes down low, I can usually climb back to higher altitudes and continue on. I was taking some really DEEP breaths, and breathing pretty fast too.