Can pilots REALLY concentrate at 35,000 feet?

[korrol]

OK - fair enough . Some very funny comments here . When you have PD, TightSlot and Paxboy on your tail you know you are in trouble....... But I really wasn't looking for a fight with anyone. All I'm suggesting is that maybe the "universally adopted" cabin pressure of the equivalent of 8000ft altitude isn't enough - and that's why it's no longer "universal".

Here's a quote from Boeing test pilot Heather Ross who's logged 1000 hours in the , 787 which has, as we know, a minimum cabin altitude of 6000ft (and has higher humidity than aluminium aircraft). After a 14 hour flight to India she said "You don't feel like you've been beaten up.You're not dry and thirsty all the time."
At 38,000 feet the 787 had a cabin pressure of equivalent of 5,400 feet (about the equivalent of living in Denver) .When the aircraft climbed to 43,000 feet the cabin altitude was at the 787 comfortable minimum of 6,000 feet.

So why has Boeing gone to all the trouble to rock the boat and increase cabin pressure on the 787 when passengers and aircrew are (to judge from this thread) apparently so happy to fly at a cabin-altitude of 8000ft? The simple answer is that they aren't.

Blake Emery - director of cabin design - says Boeing's research shows what's described as "passenger discomfort" on ordinary non-787 flights with cabin pressure at 8000ft . This shows up (according to Boeing) in the form of headaches, muscle cramps, and feelings of fatigue after three to five hours in the air - and there's no evidence that, on an ordinary airliner, the pilots are feeling any better than the passengers. (The FAA found that pilots' nighttime vision deteriorates once cabin altitude drops to 5000 feet - never mind 8000)

Lastly - just to return to the question of the lower amount of oxygen in heated rarified air which amused Magnus P . A cubic metre of warm air, as Magnus P will remember from his Form 1 Physics classes, contains fewer molecules of oxygen (and all other gases come to that) than does cold air. The proportion of oxygen is the same - 23% or thereabouts - but it's less dense..

........And, what's more, remember that 60% of cabin air has already been recycled (i.e. breathed). - but we won't go there.