Originally Posted by
doobierw
I'm also fairly certain that when the seatbelt sign is on, the lav occupied lights will illuminate. Therefore, you might see the lav occupied light on when: A. Flight attendants have locked it as part of a security procedure. B. Flight attendants have locked it as part of takeoff/landing procedure. C. Seat belt sign is on. D. Lav is actually occupied. E. Lav is inop and locked per a maintenance procedure.
I have never seen the lav light illuminate/deluminate based on the seatbelt sign. I have seen FA's manually turn on the light, or the more common, lock it from the outside.