What happened
On March 4, 1967, at approximately 09:56, a Jodel D-II, registration HB-SUW, departed from the Speck-Fehraltorf airfield for a local flight accompanied by one passenger. The flight proceeded normally until approximately 11:00, when the aircraft returned to the airfield to perform a standard landing pattern.
As the pilot turned into the landing direction, the aircraft suddenly stalled and dropped from an altitude of about 150 meters. The aircraft entered a spin, completing at least two rotations before impacting the ground near the Gutenswil-Fehraltorf road close to residential buildings. Both occupants sustained fatal injuries, and the aircraft was destroyed upon impact. There was no significant damage to ground structures.
The investigation
Investigators examined the wreckage and the flight circumstances. The investigation found that the engine was operating at high power at the moment of impact, as evidenced by the condition of the propeller and the position of the throttle, which was set to full power. No mechanical defects were found in the engine or the airframe.
Witnesses on the ground observed the aircraft's descent. Some noted that the engine appeared to be at idle just before the drop, followed by a sudden increase in power. While a medical examination of the pilot revealed significant coronary artery disease, investigators determined that the flight behavior did not suggest a sudden loss of consciousness. The aircraft's flight path remained controlled until the critical moment of the stall.
Findings
- The primary cause of the accident was likely the underspeeding of the aircraft below its minimum flying speed during the landing approach.
- The pilot had limited experience with this specific aircraft model, having only performed a few training flights on it following a three-year hiatus from this type.
- The aircraft's tendency to stall during uncoordinated turns may have contributed to the loss of control.
- There was no evidence that the presence of other aircraft in the vicinity, such as a nearby Cessna 150, interfered with the pilot's ability to complete the landing.