In FAA land, if above FL 410, one pilot has to be wearing a mask at all times. Yes, above FL 250, if one pilot leaves the cockpit, the other has to wear a mask, regardless of the type installed.
Didn't know that. Does anyone actually do it? On our ships, the Eros masks are great but we're told re-stowing is an engineering function...
Since, on SAFA checks, I have heard that the inspector has checked the O2 levels on N-registered planes for signs of O2 use when the cruising level was clearly above 410, what is the EU-OPS regulation, in it's entirety?
Had a quick search through EU-OPS for "oxygen" and couldn't find any reference to 40K+ flight. Only requirements for O2 over 10K and quick-don over 25K.