The pilots were competing in the Austraglide '86 international gliding championships. During a cross-country exercise a number of gliders were thermalling in the same general area. The pilot of D-2870 entered a thermal at about 4000 feet above ground level. His entry was made via a 45 degree bank right turn, but after turning through about 450 degrees the left wingtip of his aircraft contacted the forward under-fuselage area of VH-HNZ. This aircraft had been in a left turn with about 12 degrees angle of bank. Following the collision, both aircraft remained under control and were flown to the planned destination without further incident. Neither pilot saw the other aircraft prior to the collision. The pilot of VH-HNZ had been turning to adjust his track and had been watching other gliders well below his level. Visibility forward and downward is somewhat restricted in this particular model of glider. The pilot of D-2870 advised that he was turning towards the sun and climbing when the collision occurred.
