What happened
On August 29, 1964, a Stinson 108-3, registration HB-TRP, departed from Birrfeld Airport for a private flight carrying the pilot and three passengers. During the takeoff roll and initial climb, the pilot maintained a high angle of attack, preventing the aircraft from gaining sufficient airspeed.
As the aircraft reached an altitude of approximately 35 to 40 meters, the pilot attempted to avoid flying over a nearby railway line by initiating a shallow left turn. This maneuver caused the aircraft to lose lift and sink. The plane struck a potato field roughly 750 meters from the end of the runway, where it caught fire and was destroyed. The pilot and one passenger sustained serious injuries, while the other two occupants remained unharmed.
The investigation
The investigation examined the aircraft's configuration, the pilot's credentials, and the mechanical state of the plane. It was established that the aircraft was trimmed significantly in a tail-heavy position (approximately -10 degrees). Additionally, a previously noted maintenance deficiency regarding the stall warning horn—which was set to trigger too late—had not yet been rectified.
Investigators also noted that the pilot's license was technically invalid due to an expired medical examination. However, the commission determined that the pilot's lack of recent flight experience and the aircraft's trim state were more critical factors than the administrative status of his license.
Findings
- The primary cause of the accident was that the pilot flew the aircraft at an excessive angle of attack during the takeoff and initial climb.
- The aircraft was in a heavily tail-heavy trim configuration, which likely impaired the pilot's control feel.
- The pilot's decision to initiate a turn at low altitude and low airspeed directly led to the loss of lift.
- A malfunctioning stall warning horn may have contributed by failing to provide timely warning of the approaching stall speed.