It seems that one some airlines operated by developing countries, there are DOZENS of flight crew - Olympic on the Sydney route always seem to have loads of semi-uniformed geezers up there, leaning against panels, sitting in jumpseats. All smoking. I guess the answer is four, at least on anything normally operated at any one time by two aircrew. I guess on a clockwork 747 or DC10 six is not inconceivable, if there is a relief person for each position on the flight deck (capt., f/o, f/e). In the USSR days of Aeroflot, god only knows since most of their fleet (including the Tu134) required a crew of four. Plus skymarshalls etc. Could be 10 on an Il62? Or am I getting carried away now?
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz