What happened
On July 25, 2013, at approximately 13:21, an LS 8-18 glider, registration HB-3287, crashed into a mountain slope approximately 2 km north of Ulrichen, in the Obergoms region of Switzerland. The flight began as a recreational soaring mission, towed from Münster airfield by a Super Dimona.
During the flight, the pilot released from the towline at an altitude of roughly 2,200 meters near the Geschinergale area. Seeking to utilize thermal lift, the pilot performed several maneuvers, including a series of turns near the Ulrichengale. While attempting to extend a second thermal turn into a side valley, the pilot encountered a sudden zone of strong descending air. While executing a turn to avoid the terrain, the pilot lost control of the aircraft, leading to a high-impact collision with the steep, vegetated mountainside at an altitude of 2,170 meters.
The investigation
Investigators from the Swiss Transportation Safety Investigation Board (SUST) analyzed flight data from the aircraft's FLARM collision warning system, as well as statements from the pilot and colleagues. The investigation examined the aircraft's configuration, noting that while the total weight was within limits, the center of gravity was positioned near the rear limit due to the installation of a battery in the tail compartment without corresponding nose weights.
The wreckage analysis revealed significant structural damage, including a broken fuselage and separated wing components. The investigation also reviewed the pilot's flight experience and health, finding no evidence of impairment or medical issues prior to the accident. The pilot was able to initiate a rescue call via mobile phone shortly after the impact.
Findings
- The primary cause of the accident was the pilot losing control of the glider during a turn, likely due to flying at a speed below the minimum required for flight.
- A contributing factor was the early release from the towline, which left the pilot with limited margin to adapt to the local atmospheric conditions.
- The rearward position of the center of gravity contributed to the loss of control during the maneuver.