What happened
On the morning of 24 May 2014, the Howick Gliding Club was conducting regular operations at Howick Airfield, using a dual drum winch machine to launch gliders. During the fourth launch of the day, a Schleicher ASK 13, registration ZS-GIA, was released from its cable at approximately 1,300 feet above ground level.
Following an established climbing pattern, the pilot directed the aircraft toward the face of a nearby hill to utilize rising air. While the initial climb appeared uneventful to onlookers, the aircraft disappeared from view once it reached the ridge. The glider subsequently struck the ground at a steep angle, causing the right wing spar to break and the cockpit to collapse. The passenger was killed instantly upon impact. Although the pilot managed to extricate himself from the wreckage and contact club members to report the emergency, he succumbed to his injuries before rescue services could reach the remote site.
The investigation
SACAA AIID investigators examined the wreckage and the flight sequence to determine the cause of the impact. The investigation confirmed that the Schleicher ASK 13 was properly maintained, with its last periodic inspection completed only 11 hours prior to the accident. The aircraft was found to be in good condition, with no evidence of mechanical failure or structural defects prior to the crash.
Investigators also reviewed meteorological data, which indicated light and variable winds with visibility exceeding 10km. While thermals were active enough to support multiple successful launches that day, the investigation focused on the aircraft's behavior as it crossed the ridge line. The wreckage pattern, characterized by a broken right wing spar and a nose-down impact, indicated the aircraft had entered a spin after the wing struck the terrain.
Findings
- The primary cause of the accident was an error in judgement regarding altitude when encountering downward air currents.
- The aircraft encountered a thermal sink while traversing the top of the ridge.
- The impact of the right wing against the ground initiated a clockwise spin and a subsequent nosedive.
- The pilot and passenger were properly licensed and medically cleared for the flight.
- There were no pre-existing mechanical or airframe failures contributing to the accident.