1 pilot leaves f/d - Oxygen compulsory?
I heard once that (with a 2-man flightdeck) if one pilot leaves to use the toilet or something the other pilot must go on oxygen?
Is this still the case? Seems a bit OTT. Just wondering anyway, when I jumpseated an Airtours 763 home from Calgary in 1998 the F/o went to the loo for 5 mins and the Captain didn't use Oxygen, just kept chatting to me. Forgot to ask him at the time.
Thanks for any replies.