How tight should a passenger wear the seat belt?
During takeoff and landing and other moments the seat belt sign is on, I usually pull the belt as tight as possible. This is little uncomfortable, so I loosen it a bit when the seat belt sign is off. I think that one or maybe two fingers might fit between the seat belt and my body. Is this a good idea? Would wearing the belt as tight as possible give a greater risk of crushing my pelvis bone or something?
Please specify whether there is a difference between a situation where the seat belt sign is on and a situation where the sign is off.