Bob's post brought to mind a comparison with Colorado hikers and climbers. We don't hear nearly as much about issues with AMS in that state, because everyone lives at 5k or so. Even though people don't have AMS symptoms at 5k, I am sure there is a benefit. For a person living in Denver, or near Reno, they's have to hike to 19.5k in order to experience similar effects as we lowlanders do when climbing Whitney.
mentioned recently that they were consulting with a Colorado AMS physician at some clinic, and this physician was surprised to hear about AMS problems climbing to 14k. Seems pretty clear to me that the 5k threshold for people in CO provides a completely different reference point.
Ready for some Lankford trivia about that 5k?
Although the official definition of altitude illness begins at 8k, the FAA recommends that general aviation pilots flying above just 5k at night in non-pressurized aircraft use supplemental oxygen. Of course most of them ignore this recommendation, but it is there because the retina (which is actually an extension of the brain) is the most sensitive body part to hypoxia. So the small amount of lowered O2 available at 5k is enough to subtlely impair night color vision. I gave a talk to pulmonary MDs once and this older codgy pilot tried to argue with me in front of the audience. I used a paraphrase of the great line in Top Gun where Charlie tells Maverick something like, "The government sees to it that I know more about than you do."
