Several gliders were thermalling in one area during a cross-country flight. VH-IZE departed for the next thermal and the pilot, having determined that he was clear of other aircraft, began a left turn in the thermal. He then heard a loud bang and the glider pitched steeply down, however he was able to parachute to the ground. The left wing of VH-IZE had severed the fuselage of a second glider, VH-GKN, and the tail wheel area had struck the upper right wing and cockpit. The pilot of VH-GKN had been thrown from his seat but did not operate his parachute. The relative positions of the two gliders prior to the start of the manoeuvring which resulted in collision could not be established. However, the apparent relative impact attitudes of each aircraft indicate that just prior to impact VH-IZE would most probably have been in the two o'clock low position in the field of view from the cockpit of VH-GKN. VH-GKN would have most probably appeared in the seven o'clock high position in the field of view from the cockpit of VH-IZE. It is likely that the pilot of VH-GKN was incapacitated as a result of the collision.
