Ah OK. Now I get it. You're correct in that I do recall being told on occasion that we couldn't leave the departure lounge because the inbound crew were getting off. It didn't seem to be a hard and fast rule though.

in singapore,as cabin crew often we are getting on board before the arriving crew get off, particularly when a whcr or disabled punter still on board. mostly the reason pilots don't do a changeover on board is that the inbound mob are leaving the a/c at light speed. it has nothing to do with any regulations ....probably a cold frothy one is the reason