Fatigue
As Trashie said, not much in the way of fatigue management in the military in days gone by. I recall one trip, not Cyclone Tracy related, where we originated in Bulawayo, flew to Salisbury and waited three hours for our pax who were delayed, flew to Mauritius which was supposed to be a night stop. Changed to tech stop then to Perth (tech stop) to Melbourne, Canberra and Sydney. To try and get somewhere near crew duty limit compliance a replacement tech crew was requested to meet us in Perth. Only a F/O and F/E available, the F/E requiring a line check which was conducted Perth-Melbourne-Canberra-Sydney. Not 40 hours but 15.5 hours block time logged without crew rest. And some not part of it thought the B707 operations to be a "cream" job.