Originally Posted by tennisguru

I'll admit I don't fully know, but here's a hypothetical: Scheduling calls at 0300 to put you into 30 hours rest at 0500. Your phone is on DND so you dont wake up and see the VM until 0700. At that moment in time you only prospectively know that you are in rest for 28 hours. You had no prospective knowledge at 0500 while you were asleep that from that point forward you had 30 hours of rest. In my eyes even though the rest assignment is PWA compliant, you must call them by 1200 (0300 + 9 hours) to tell them you were not aware of rest starting at 0500 thus the 30 hours needs to be reset starting from the time you call them.

The prospective nature of the 30 hour rest period (and to a lesser extend the 10 hour rest period prior to any RAP/FDP) is what trips up both scheduling and pilots. But once you understand the true application of it you will see scheduling mess it up a lot.