The pilot was a member of the French team competing in the "Austraglide `86" gliding championships. At the end of a cross-country exercise the pilot reported that he was 5 kilometres from the finish line. The pilot of another glider observed that when the subject aircraft was one kilometre from the line it was apparently low. Shortly afterwards the glider collided with power lines. The tailplane was cut off by this impact and the glider then struck the ground in a steep nose down attitude. The glider was seen leaving an area of thermal activity with apparently sufficient altitude to complete the flight to Benalla. The reason why the glider subsquently descended to the low altitude which resulted in the collision with the power lines could not be determined.