Originally Posted by
NickB
There are absolute "black and white" limits but there is also a kind of "zone of discretion" before that.
And throw in that a lot of variables e.g. if a crew member is acclimatised or not and that may limit the hours etc. Computer may have a general idea but ultimately it's the SCCM's responsibility to work out the most limiting crew member's hours and inform the captain, and in delay situations discretion can be applied. Working out flight duty hours can be a minefield and not black and white. There are black and white absolute maximums but a lot of variables may increase/ decrease that maximum.