Glasflugel Standard Libelle, VH-GGV, Schleicher ASW15A, VH-GXY, Tungamar (13 km SSW of Yarrawonga) VIC, 20 January 1989

The pilots were competing in a triangular navigation exercise and were in the vicinity of the final turning point. The aircraft were orbiting in a thermal when they collided at a height of about 3500 feet above the ground. Both aircraft became uncontrollable and the pilots parachuted to safety. The investigation established that both aircraft were orbitting to the right when they collided. Examination of the wreckage showed that the right wing of VH-GXY hit the left wing of VH-GGV. The impact was on the leading edge of each wing. About two metres of the wing of VH-GXY was severed, and about one metre of the wing of VH-GGV. Neither pilot had been aware of the presence of the other aircraft in the thermal.