What happened
On 10 August 2012, a Pipistrel Taurus powered glider was conducting a local private flight departing from El Mirador (FALQ). During the flight, the aircraft's GPS data recorded a rapid acceleration, with airspeed increasing from 150km/h to over 230km/h in a span of just 6 to 9 seconds. Following this surge, the aircraft entered a parabolic descent, impacting the ground at a near-vertical angle within a game reserve in Winterton. The pilot sustained fatal injuries, and the aircraft was destroyed upon impact.
Witnesses at the scene observed the aircraft exhibiting significant longitudinal instability and severe wing oscillations. One observer noted that the wheel bay doors were opening and closing in synchronization with the pitching movements of the glider. Although the pilot attempted to deploy the ballistic parachute at approximately 500 feet above ground level, the system suffered a shroud line failure and failed to fully inflate. This resulted in increased drag, causing the aircraft to pitch up, drop a wing, and dive vertically into the ground.
The investigation
SACAA AIID investigators examined GPS flight path data, witness statements, and the wreckage to reconstruct the sequence of events. The investigation focused on the aircraft's aerodynamic state prior to the crash. Analysis of the aircraft's configuration revealed that the flaps were set to +5°, a setting intended for a recommended speed of 68km/h, which was far below the actual speed at the time of the incident. The investigation also reviewed the maintenance and operational status of the Taurus, noting that the engine was stowed for the duration of the flight as it was not required for thermal soaring.
Findings
- The primary cause of the accident was that the pilot exceeded the maximum speed limitation (VNE), which induced structural flutter and subsequent loss of control.
- The high-speed flight led to a stall before the aircraft struck the ground.
- The aircraft exhibited severe wing flexing and longitudinal instability consistent with aeroelastic flutter.
- The ballistic parachute failed to deploy effectively due to a failure in the shroud lines.
- Meteorological conditions were favorable, with clear visibility and light winds, and were not a contributing factor.