What happened
On April 8, 2007, an ASH 25 glider, registration HB-3270, departed from Hausen am Albis for a local flight. The flight lasted over four hours, during which the aircraft reached altitudes of up to 1560 meters. During the final phase of the flight, the aircraft was operating at low altitudes, between 100 and 300 meters above the ground, near the Rossberg area.
While navigating weak thermals, the glider entered an uncontrolled flight state and collided with the terrain in a wooded area near Schönalp. The impact resulted in one fatality for the pilot in the front seat, while the pilot in the rear seat sustained light injuries and was able to call for assistance using a mobile phone.
The investigation
The investigation examined the flight logs, aircraft wreckage, and the statements of the surviving pilot. Investigators analyzed the flight profile, which indicated weak upward currents at the time of the accident. The investigation also reviewed the flight experience and qualifications of both occupants, noting that the pilot in the front seat had recently obtained his license and had no specific instruction for the ASH 25 model.
Technical examination of the wreckage showed that the aircraft's weight and center of gravity were within limits and no pre-existing mechanical defects were found. However, it was noted that the shoulder harness attachment for the front seat failed during the impact. Additionally, the emergency locator transmitter (ELT) was found to be switched off at the time of the accident.
Findings
- The primary cause of the accident was the glider entering an uncontrolled flight state at a low altitude, leading to the collision with the terrain.
- A significant contributing factor was that the aircraft was being piloted by an individual with limited flight experience who had received no specific training or instruction on the ASH 25 type.
- The pilot in the rear seat was unable to intervene in time to recover the aircraft once the spin began.
- The investigation could not rule out a potential medical event, such as a sudden loss of consciousness, affecting the pilot in the front seat.