What happened
On August 9, 1968, a de Havilland Canada DHC-1 Chipmunk, registration HB-TUK, was performing a glider tow at Birrfeld Airfield. Approximately one minute after takeoff, the engine of the towing aircraft failed due to fuel exhaustion. The tow pilot, flying at an altitude of only 50 meters, released the tow rope and performed an emergency landing in a nearby field, which was completed without further incident.
The student pilot, operating a Rhönlerche II glider, registration HB-594, initially turned left to return to the airfield. Realizing the aircraft was too low to clear a road located at the end of the runway, the student pilot attempted a right-hand turn to land parallel to the road. During this maneuver, the glider entered a stall and plummeted from an altitude of approximately 5 meters, striking the ground.
The investigation
The investigation established that the tow aircraft had been flying for approximately 2 hours and 36 minutes since its last refueling. This duration aligned with the calculated fuel consumption limits of the DHC-1 Chipmunk, confirming that the engine failure was caused by a lack of fuel. The investigation also noted that the student pilot had very limited solo flight experience, having completed only eight solo flights prior to the accident.
Findings
- The engine failure in the towing aircraft was directly caused by fuel exhaustion.
- The tow pilot failed to verify the fuel gauges prior to the takeoff.
- The student pilot, due to a lack of experience, executed an improper turn at an extremely low altitude.
- The simultaneous application of back pressure and right rudder caused the glider to lose airspeed and stall, leading to the impact.