The pilot had completed a soaring flight of some two and a half hours duration. The aircraft was seen to make an apparently normal approach, but during the landing flare the tail cone contacted the ground and the glider pitched nose down. The forward fuselage area then struck the ground heavily. The glider received only minor damage, however the pilot suffered serious back injuries. The pilot was using three additional soft foam cushions on top of the seat to elevate his position in the cockpit. It is probable that during the hard landing the resilient cushions compressed rapidly and the pilot continued downward after the aircraft had started to rebound and then stopped abruptly as he hit the seat pan. This accident was not the subject of an on-site investigation.