The FAA's legal definition of night begins at the end of evening civil twilight - not sunset - and the currency window for carrying passengers runs from one hour after sunset to one hour before sunrise.
Boeing is ending 767 freighter production not because the aircraft failed, but because new ICAO CO2 emissions rules set a certification deadline it can't meet.
FAR 91.119 sets minimum safe altitudes in three layers: emergency landing capability everywhere, 1,000 feet over congested areas, and 500 feet over open areas.