What happened
On the morning of 5 October 2023, a Grob Astir CS 77 glider, registration ZS-GWN, was participating in the South African National Gliding Championships in the Club Class. The flight began with an aerotow from Potchefstroom Aerodrome (FAPS) in the North West Province, intended to conclude with a return to the same airfield.
During the flight, the pilot released from the tug aircraft at an altitude of 6,257 feet, noting that the atmospheric conditions initially felt like thermal activity. However, after approximately 19 minutes of flight, the pilot was unable to secure enough lift to maintain altitude or return to the aerodrome. As the aircraft drifted outside the gliding range of FAPS, the pilot sought a place to land. Unable to find a suitable landing site, the pilot opted for an out landing in an open field characterized by very rocky terrain. Upon impact with the rocks, the aircraft's undercarriage and right wing sustained substantial damage. The pilot escaped the incident without injury.
The investigation
The investigation examined the aircraft's airworthiness and the pilot's credentials. The Grob Astir CS 77 was found to be airworthy, with a valid Authority to Fly and a recent annual inspection completed in September 2023. The pilot held a valid Glider Pilot Licence and a current medical certificate, and was deemed appropriately rated and fit for the operation. Meteorological data at the time of the occurrence indicated clear skies (CAVOK) with a temperature of 32°C and light northerly winds.
Findings
- The primary cause of the accident was the pilot's decision to perform an out landing on rocky terrain following a failure to obtain sufficient lift to reach the intended aerodrome.
- The aircraft sustained significant structural damage to the wing and undercarriage due to the nature of the landing surface.