Impact absorption system, particularly for aircraft seats

An impact energy absorption system for an aircraft seat, comprising mounting means for the seat including at least one substantially upright support to which the seat is coupled for movement therealong between a first, unloaded position and a second, crash-induced position, a deformable rod having a first contoured section and a second contoured section, defining a shoulder, abutting against a deforming die, said second section passing through the die and being coupled to the seat so that said movement of the seat is restrained by and causes deformation of the said first section by said die while the said first section is being pulled therethrough, the system further comprising self-adjusting variable die jaw means surrounding the said second section defining an aperture, the jaw means being moved in the direction of the rod by the weight of an occupant of the seat to automatically close said aperture by an amount proportional to the weight of the occupant of the seat, to thereby cause a further deformation of the said first section by the jaw means while said first section is being pulled through the jaw means towards said second position.