If it can happen to climbers, why would pilots be immune?
Well - of course I'm not a doctor. ...And indeed I'm not much of a pilot either. But I did once manage to get a Victa Airtourer to climb to over 9000 feet - at which - point both plane and pilor were struggling.
But really, what we're doing to passengers (and pilots) in airliners, is asking them to ascend from not much above sea level to 8000 feet very quickly.
There's really not much difference between people in a plane and people climbing mountains. ....And we know altitude sickness can begin to affect otherwise healthy people at just 5000 feet after just a few hours ( maybe over three or four) at that level.
Acute Mountain Sickness (AMS) apparently starts to manifest itself at anything above 6,500 ft.. Symptoms include headache, fatigue, stomach illness, dizziness.
..........So, if it can happen to fit people like climbers - what's so special about pilots - or, come to that, passengers?
Frankly I have to confess I don't feel all that great after a long flight - like one of those bone-crackers from Los Angeles to London.. And I guess that goes for a fair proportion of the other passengers.......... But we knew what we were getting into when we booked - and if our performance is poorer than normal it probably won't matter.that much ...As for the pilots though - Well that's a different matter..
Air France 447 had been in the air for around 4 hours when the pilots (at cabin pressurre of 8000 feet) were overwhelmed by the emergency and clearly weren't able to think straight. The Captain had been off-watch asleep - but how many pilots - let alone passengers - when roused from a relatively low-oxygen slumber at 8000 feet would be sharp enough to deal logically with a multi faceted emergency like that?