CTLSi wrote:I fly at 10 and 11k routinely. No effect. By the way, I live at 5500 feet. A sea level guy might not be able to do it, or a smoker or ex smoker, but it's no problem for those of us who have the red blood cells accumulated living at altitude.
There is not "no effect". There is no effect that you have perceived
. Since perceptions are affected by hypoxia, the statement is dangerously flawed. I would bet money that every single human being on Earth has measurably worse performance in some regard at 10,000 feet MSL than at sea level.
In any case, flying higher is safer than flying lower.
Sure, until it's not. Is flying at 18,000ft AGL with no supplemental oxygen safer than flying at 1000ft AGL?
There are few absolutes here. Hypoxia can be just as deadly as flying into the ground. There is some point at which hypoxia risk outweighs those risks associated with lower altitude flight, and that point is different for each and every person. Unless you've done a hyperbaric chamber run with cognitive testing, there is no way to know what that point is in advance.