Abstract: A notched-energy absorber for attenuating high level accelerations such as ould occur during aircraft crashes, thereby avoiding injury to a user. The energy absorber force-displacement curve has a large initial spike, followed by a valley or "notch" and then by a constant force level intermediate the spike and valley levels. In one embodiment, a conventional square-response type shock absorber is connected between a vehicle seat and the vehicle body by a shearable diaphragm fixed to vehicle structure. The diaphragm shears at a notch when it experiences an initial high force, after which the conventional absorber moves freely without deforming until it encounters a stop. The conventional absorber then elongates or compresses in a conventional manner. In an alternative embodiment, a spring is connected between the seat and the vehicle body. Initially, the spring is compressed by experienced forces until at a predetermined force level it forces out a retaining clip or ring.