Thank you, like I said i have the world's most restricted pilot's licence. This is all very interesting and confirms my view of Hollywood. I would have asked my cousin who flew WW2 Typhoons, they were on oxygen from start to finish, CO issues, but alas he moved on to a better place. He mentioned filling a tank with beer and flying with it to occupied France "it didn't taste quite right but by god everyone was pleased to have the beer".