What happened
On April 5, 2009, at approximately 18:20, a Humbert Tétras 912 BS ultralight aircraft, registration 57-ABO, was conducting a local flight near Marsal, France. The flight originated from the Dieuze aerodrome, where the pilot and one passenger departed at 17:35.
While flying approximately ten kilometers from the airfield, the crew spotted a farmer working in a field and decided to approach to acknowledge him. The pilot performed a turn to return toward the field at an estimated altitude of 600 feet. During this maneuver, the pilot reduced airspeed and deployed a flap setting. As the passenger opened the right door to wave to the farmer, the right wing suddenly dropped. Although the pilot attempted to regain control of the aircraft, the Humbert Tétras 912 BS struck the ground. A post-impact fire broke out, destroying the aircraft. The farmer was able to assist in extracting the unconscious passenger from the wreckage. The accident resulted in two serious injuries.
The investigation
Investigators examined the aircraft's flight controls and found no mechanical failures that contributed to the accident. The investigation also reviewed the pilot's actions and the environmental conditions at the time of the event. Meteorological data indicated CAVOK conditions with a light wind from 020° at 5 knots.
Findings
- The pilot's focus on maintaining visual contact with the farmer distracted from essential flight parameters.
- The pilot was flying at a speed near the aircraft's stall speed without realizing it.
- The aircraft was not equipped with a stall warning device.
- The maneuver involved a tight turn at low altitude and low airspeed, leading to an unintended slip/skid condition.