arggggggggggghhhhhhhhhhhhhhhhhhhhhhhhhhhhhh . Neither of you are correct nr do I think either of you are AME's in fact have either of you passed HPL ? I regulalrly fly commericially and never get ill . Every pilot who has studied HPL knows exactly what I put in my last thread which I am not going to repeat.As an Ex RAF tyep I have been in a baro chamber on a number of occasions and know all the effects of o2 deprivation etc etc However I think based on the info given here by the two experts I will go back to gatwick and hand in my class one and tell them they dont know what their talking about.