What happened
On June 9, 1964, a Grunau Baby II glider, registration HB-195, was conducting a flight as part of a flight training course. The pilot had departed from Birrfeld at 10:23 CEST with the objective of attempting a five-hour duration flight. After successfully maintaining flight for over three hours, the aircraft encountered a sudden, strong downdraft of approximately 4 m/s at an altitude of roughly 500 meters above ground level near the Wildegg-Holderbank area.
Realizing that the remaining altitude was insufficient to clear the Kestenberg ridge, the pilot determined that a return to Birrfeld was not possible and initiated an emergency landing in an open field. The pilot selected a landing site but approached the area with a tailwind, utilizing a pushing technique. This approach resulted in a failed touchdown, causing the aircraft to break up upon impact.
The investigation
The investigation examined the flight conditions, the pilot's decision-making, and the environmental factors at the time of the accident. The weather was characterized by high-pressure conditions with a moderate Bise wind and good visibility of 15–20 km. The investigation focused on why the pilot approached the landing site in a manner that led to the loss of the aircraft.
Findings
- The pilot was an experienced student with approximately 19.5 total glider flight hours.
- The aircraft, owned by the Birrfeld Flight School, suffered approximately 70-80% damage, rendering it a total loss.
- The pilot remained uninjured during the event.
- The primary cause of the accident was that the pilot approached the chosen landing site with a tailwind and executed a landing that was too rapid and pushing.
- It was noted that the pilot failed to utilize available visual cues, such as smoke from nearby cement factory chimneys, to determine wind direction. While the pilot's choice of terrain was appropriate, the direction of the approach significantly contributed to the crash.