Originally Posted by
Zeeb
What I've seen most commonly, and what I think is a perfectly acceptable solution, is for FAs on those aircraft to prevent people in Y from hanging out and waiting for the F bathroom to open up (both to prevent a crowd and so F passengers don't have to wait in line behind Y passengers) but otherwise not worry about it.
On a recent flight, a C+ passenger came forward to use the already occupied F lavatory, and the flight attendant dutifully instructed her to wait behind the (closed) curtain. When the lavatory opened, another F passenger jumped in. The C+ passenger returned, only to be sent back behind the curtain. This pattern continued for another F passenger or two. Eventually the C+ passenger began talking aloud to herself about how ridiculous her treatment was, but she eventually got the hint and settled for an aft lavatory.