Blanik L13, VH-GBT, Tumut NSW, 12 January 1985

Following a dual check and a short solo flight, the pilot was authorised to conduct a soaring flight of not more than one hour's duration. The glider was subsequently launched from an aerotow after take-off into a light northerly wind. It was observed soaring in the vicinity of the aerodrome within an estimated height band of 3000 to 6000 feet above ground level. During the flight the wind on the ground changed to become a gusty south-westerly at about 10 to 15 knots. The shade temperature was 36 degrees Celsius and localised areas of turbulence were reported by other pilots.

The pilot did not return for a landing for approximately two hours, despite the pre-flight briefing. When he returned, the aircraft was positioned for a landing into the north, apparently without reference to the changed wind conditions. During final approach the glider was seen to pitch down into an almost vertical dive. It struck the ground some 200 metres before the strip threshold and came to rest inverted. Subsequent examination of the wreckage did not reveal any defect or malfunction that might have affected the pilot's ability to safely control the aircraft. It was apparent that the glider had been in a normal wings level approach configuration immediately before the pitch-down which occurred at a height of about 100 feet above ground level.

It was considered possible that the aircraft could have been affected by turbulence, or that the pilot may have suffered from heat stress and fatigue. However, insufficient evidence was available to enable the precise factors in the occurrence to be determined.