MikeFerrara once bubbled...
That's NOT the procedure. We pull the gate closed behind us and lock the lock so that nobody can lock us in. We make it look locked but it isn't. If I remember right the key is also required to lock the lock (I dived it in March). It would be pretty hard or impossible for two teams to pass eachother and not know it so if the exiting team passed a team on their way in we hand the key off so the team who is the furthest in always has the key. The gate is never locked with any one inside.
This is the procedure given to us by the management and it works fine. I agree, no cave diver in their right mind would allow themselfe to be locked in a cave.