End of a tiring duty cycle and a very hard Qtr in the peak of a circadian low...
It gets one thinking. I've personally found myself nearly nodding off during the approach phase of an usually tiring 9 hour / 2 landing duty cycle doing PM for the F/O. This is an effort just to keep awake...
What happens if you have a complicated decision to make towards the fag end of that duty cycle...
It bothers me...and thus came FRMS.