What happened
On the afternoon of 14 May 2023, an ASW-20 glider, registration ZS-GMK, was being aerotowed from Worcester Aerodrome (FAWC) by a tug aircraft. The flight was being conducted under visual meteorological conditions as part of a private operation. After approximately ten minutes of towing, the glider pilot released the tow rope with the intention of returning to the aerodrome.
While flying near the Villiersdorp area, the pilot encountered deteriorating lift caused by the local topography. As the aircraft lost altitude, the pilot attempted to maintain height but found it impossible, necessitating an out-landing in an open field. During the maneuvers to prepare for landing, the aircraft entered a right-hand turn, during which it stalled and the right wing dropped. The glider struck the ground in a nose-down, right-wing-low attitude, resulting in substantial damage to the airframe.
The investigation
SACAA AIID investigators examined the flight conditions and the sequence of the impact. The investigation confirmed that the pilot was properly licensed and medically fit for the flight. Meteorological data from the South African Weather Service indicated strong south-westerly winds, with speeds between 20 and 23 knots and gusts reaching 32 knots, at the time of the occurrence.
Following the impact, the pilot sustained a fractured right ankle and required surgery. The tug pilot, who had returned to the aerodrome to pick up a second glider, was alerted by a person on the ground and subsequently located the wreckage on a ploughed field approximately 20 nautical miles southwest of Worcester Aerodrome.
Findings
- The glider lost sufficient lift and altitude due to topographical influences, making recovery impossible.
- The aircraft entered a stall during a right-hand turn while the pilot was attempting to maneuver for an out-landing.
- The out-landing was performed in a downwind direction.
- There were deficiencies in flight planning and the acquisition of reliable weather forecasts to ensure the safety of the soaring flight.