I'll argue that a sub 140 knot, wings level emergency or botched landing should be survivable without significant number of spinal injuries.
In most of these accidents other than cracking in one or two pieces, the fuselage does not deform. Yet there is significant space below the floor, which is full of crushable stuff in the form of bags and bag containers.
The lower half of the fuselage could be designed to deform and the top "semi circle" comprising of passenger floor and ceiling, would form the safety cell.
The bag containers, when loaded could themselves form part of a system of energy absorption.
The design imperative that the tube should be strong enough to withstand pressure differential should not be affected as those pressure forces are exerting force from the inside, whereas crash energy is being exerted from the outside.
Last edited by mickjoebill; 4th Aug 2013 at 05:03.