They did not have pressurised cabins (mostly) in ww2, it gets damm cold in a bomber at altitude.

If your plane goes down in the middle of a battlefield, you'll need a good coat...

You're kind of fucked in that case regardless, and waterproof jacket will be the least of your concerns. All you have is a small handgun.

Pilots spend most of their time flying over either friendly territory or open water. Assuming they survive the crash intact, cold is overall their #1 threat.

Wanted to add that a bunch of planes from back then didn't have sealed, heated cockpits like we know today.

The vast majority of military cockpits aren't pressurized even today.

Yes, they are (F-16 most commont)[1] (F-16 pressurized)[2]. It's just not enough to avoid needing additional air supply to prevent hypoxia.

1. https://en.wikipedia.org/wiki/List_of_active_United_States_A... 2. https://aviation.stackexchange.com/questions/73143/is-the-f-...

I didn't clarify Ventile was created to increase their chances of surviving if shot down in the North Sea.