Great idea daz - as the seat back collapses with the weight of the flying passengers hitting it from behind you'll get squeezed 'twixt seat and seat back and your insides will squish out. Cos if the seats are breaking off the floor so your legs get crushed then I reckon that's what'll happen.
My plan was to get a cushion and stuff it between seat belt and me body such as to spread the forces over a wide area. I have no idea if this is a good idea or not but apart from bursting into tears I can't think of much else to do to pass the time before impact.