What happened
On September 6, 1964, a pilot operating a DH-85 Leopard Moth, registration HB-ALI, arrived at the Beromünster airfield to attend a local fly-in event. The flight originated from Speck-Fehraltdorf with two passengers on board.
At approximately 12:50 PM, the pilot attempted to land on runway 34. Witnesses and the pilot reported that the touchdown was initially correct, occurring near the centerline roughly 30 to 50 meters past the threshold. However, shortly after the aircraft touched the ground, it bounced slightly and then began to veer sharply to the right. The pilot was unable to regain directional control, and the aircraft traveled in a shallow right-hand arc across the airfield. At a speed of approximately 40 km/h, the aircraft struck a drainage canal that was about 1.5 meters deep. The impact caused extensive damage to the airframe, including a collapsed right landing gear, structural damage to the fuselage and wings, and a crushed engine mount. The pilot sustained one minor injury (a laceration to the forehead), while the two passengers remained uninjured.
The investigation
The investigation examined the mechanical condition of the aircraft, the environmental conditions at the time of the accident, and the pilot's actions. Investigators inspected the braking system of the HB-ALI and found that the brakes were functioning normally and applied both wheels evenly. Tire marks on the ground were consistent and did not indicate any mechanical failure or uneven braking. The investigation also noted that the airfield surface was wet due to recent light rain and overcast conditions.
Findings
Technical analysis and witness testimony led to the following conclusions:
- The aircraft likely began to veer to the right immediately after touchdown due to a crosswind gust or a slight initial drift.
- The pilot's reaction to the deviation was likely delayed.
- Due to the sudden nature of the excursion, the pilot likely applied insufficient left rudder while braking, which prevented the aircraft from correcting its course back toward the runway centerline.
- The pilot's application of the brakes was deemed too late and too weak to prevent the aircraft from exiting the runway area.