Originally Posted by
MarcK
You've got to be kidding. What's the problem with 10K feet? Oxygen levels start (in the US) at 12,500. Finding your aircraft's service ceiling isn't a big deal.
Yes, when climbing I start to feel the altitude at about 9,000 feet and get slower and slower the further up I go (I live at 1200 feet ASL). I don't notice any cognitive effect at the top of Rainier, 14,400 feet but I do start puffing getting there.... Loveland Pass in Colorado is a paved road at 11,992 feet; no oxygen required.