What happened
On August 27, 2016, a Sportine Aviacija LAK-17A glider, registration G-CKKK, departed from the La Cerdanya aerodrome in Spain for a private flight. After being towed to an altitude of approximately 2,392 meters, the pilot began searching for thermals. After gaining about 540 meters in altitude over an hour, the pilot found insufficient lift and turned east, reaching an altitude of 3,295 meters.
As the pilot failed to find further rising air, they turned back toward the west, crossing a ridge and entering a valley oriented east-west. The aircraft followed the valley floor at a decreasing altitude, dropping from 160 km/h to 100 km/h. During a left-hand turn, the left wing of the glider struck medium-voltage power lines, leading to a fatal impact with the ground. The pilot was killed, and the aircraft was destroyed.
The investigation
Investigators analyzed data from the aircraft's Oudie GNSS receiver, which allowed for a reconstruction of the flight path and engine usage. The investigation focused on the use of the aircraft's Front Electric Sustainer motor, which is powered by two batteries.
Examination of the wreckage revealed that the left wing had collided with the electrical lines. The propeller blades were broken at the hub, with one blade showing friction marks consistent with contact with the power lines. This damage suggests the motor was not in its retracted position at the time of impact. GNSS data confirmed that the motor had not been used for the majority of the flight, but was activated approximately one minute before the collision. The investigation also reviewed the pilot's experience, noting they had 210 total flight hours, with 35 hours on this specific type.
Findings
- The accident was caused by a succession of trajectory choices made while searching for and exploiting thermals.
- The pilot operated at an excessive distance from a suitable aerodrome within mountainous terrain that was incompatible with an emergency field landing.
- The pilot attempted to use the electric motor very late in the flight, likely due to the increasing proximity to the terrain.
- The pilot could have opted to terminate the flight earlier when it became apparent that thermal conditions were insufficient.