What happened
On August 1, 1968, a Piper PA-18 Super Cub was performing glider towing operations for the Segelfluggruppe Bern at the Bern-Belpmoos airfield. During the third flight of the day, the pilot completed a standard towing maneuver, releasing the glider and performing a typical circuit.
As the pilot transitioned into the final approach, the aircraft was flying at an altitude of approximately 40 meters. The pilot reduced the engine to idle and adjusted the flaps to a 50-degree setting. While passing over a 20-meter-long patch of grain located just before the runway, the aircraft's landing gear became entangled in the crops. In an attempt to recover, the pilot applied full power but then subsequently reduced power again while maintaining full back-pressure on the control column. This sequence caused the aircraft to strike the ground nose-first, resulting in the aircraft flipping onto its back 20 meters past the start of the runway.
The investigation
The investigation examined the flight parameters, the environmental conditions, and the pilot's actions during the final approach. Investigators reviewed the aircraft's maintenance history, noting the engine and airframe had undergone recent overhauls. The weather at the time of the accident was reported as clear and calm, with light winds from the north at 1-2 knots.
Findings
- The pilot initiated an excessively short approach, likely attempting to land closer to the glider parking area to save time.
- The pilot's claim that a downdraft caused the sudden loss of altitude was inconsistent with the recorded calm wind conditions and the likely presence of updrafts over the sun-warmed grain field.
- The loss of altitude was likely a natural consequence of reducing power while using high flap settings (50 degrees).
- The pilot failed to maintain sufficient clearance over the grain field located ahead of the runway.
- The accident was caused by the pilot's delayed and insufficient power correction after the initial encounter with the crops.
Safety action
No specific safety recommendations were recorded in the final report.