And don't forget the overhead lockers.... if there is sufficient force at the moment of impact, the lockers can be ripped from tehir fastenings and fall downwards (once some come away, there will be a ripple effect pulling them all down). On a full flight, there is a lot of weight in the lockers to do some serious damage..its better if the weight is spread over the seat back tops.you may sustain some injury but will still have the ability to crawl to safety....