Name one that had unlimited oxygen, totally reliable systems, constant heat?
Where's that story of a P-38 pilot trainer hearing 2 students commenting about how a P-38 can't climb, so he says "We're goin climbing and we aren't stopping until you 2 say so" so they climb and climb and climb until they're freezing cold, barely able to speak, and one of them calls it off half frozen to death?
Because pilots can really pull Gs when their muscles are nonfunctional, eh?
To answer, things like the I-16 had none if I recall. Most soviet planes had none. Heck, most soviet planes had cardboard radios that never worked, too!
Then we get WW1 biplanes flying around at 20k which is absurd. These craft definitely had no O2, as well.
I'd like to see something. Blackouts will do, but some sort of time limit (like WEP, nonrechargable, but reloadable on hotpad) where it kicks in at certain alts.