The pilot, who was an experienced glider pilot and instructor, was taking part in a gliding competition. Only 2 of the 12 competitors were able to complete the exercise, the remainder being required to outland. Almost 4 hours after being launched, the aircraft was sighted in a right hand circling descent, apparently being manoeuvred for an outlanding. At low level, the angle of bank was seen to suddenly increase and the nose dropped. The right wing struck the ground and the aircraft cartwheeled before coming to rest about 34 metres from the point of initial impact. It was evident that the aircraft had entered an incipient spin at too low a height above the ground to enable the pilot to recover control of the aircraft. The reason for the loss of control could not be determined.