Working Hours? Try days...
Our flying rules used to say that 16 hours was the limit, but that for brief periods a 24h day was permissible with a partially augmented crew. In fact they still say that, but are comprehensively bent to acheive that operational task, with 16h days the new normal minimum and 24h days quite common. Ever tried sleeping in an airline seat? No bunks for us! And guess who's crew position is not augmented?
Cumulative fatigue is taken seriously in the RAF, right up to the point that it gets in the way of something else. How long before someone makes a critical error due to fatigue?