[fish314]

True. If you are talking about a stall speed in a "fast mover" like a fighter at a high altitude, you might start seeing some variations. Might be noticable in airliners also, but I'm not sure. I flew 707's (actually KC-135's) for about 5 years, but we never flew close enough to stall speed (especially at high altitude) to ever notice it. For us, the big number that we looked at was gross weight, as opposed to altitude.