It wasn't a problem in those days.
When I was young, and as an off duty Ops guy assisting the crew with overpowering (having a wrestling match with) a disruptive passenger on the outbound LON/LAX leg we, kinda had a reputation for it, had one hell of a crew party in the Santa Monica hotel.
Next lunchtime, before the 3pm (ish) departure back to LON, we were in Ye Olde Kings Head drinking and playing darts etc., both cabin crew and one of the pilots, I was cockpit jumpseating it on the return leg, the Flight Engineer checked me out on his panel before he buggered off to the downstairs galley for a nap, the Captain announced that he was to take a nap however the First Officer, having been drinking, conked out also.
There I was, an off duty Ops guy, in command of a wide-body jet!
It wasn't a problem in those days
