What happened
On August 20, 2004, at approximately 17:00, a Synairgie Skyranger ultralight, identified as 40-FS, was involved in a fatal accident at the Duhort-Bachen microlight airfield. The flight was an unplanned local excursion following a meeting between the pilot and a former student, who was acting as a passenger. The pilot had originally intended to deliver a part to a relative nearby but decided to use the opportunity to practice short-field takeoffs and landings.
The aircraft departed from the Aire-sur-l’Adour aerodrome and proceeded toward the Duhort-Bachen platform. During the flight, the pilot handed control of the aircraft to the passenger. After completing a takeoff and landing on runway 25, the aircraft began an initial climb to approximately 600 feet. As the passenger attempted a left turn to rejoin the downwind leg, the aircraft encountered severe turbulence. This atmospheric disturbance caused the aircraft to pitch up and bank sharply to the left. The pilot attempted to regain control, but the aircraft entered a steep nose-down attitude, leading to a collision with the ground.
The investigation
The investigation focused on the aircraft's flight path and the environmental conditions at the time of the accident. Examination of the wreckage revealed that the Synairgie Skyranger struck the ground in a significant nose-down attitude. No mechanical anomalies or technical failures were identified in the aircraft's components that could have contributed to the loss of control.
Meteorological data and witness accounts confirmed highly unstable weather. At the time of the accident, the site was experiencing winds from 270° to 290° at 10 to 15 knots, with gusts reaching 25 to 30 knots. The presence of Cumulonimbus clouds at 1,500 feet and a nearby thunderstorm cell produced moderate to severe turbulence. A witness near the airfield corroborated the presence of violent westerly gusts, and another pilot reported terminating a separate local flight early due to similar turbulent conditions.
Findings
- The primary cause of the accident was the improvisation of a flight exercise under unfavorable meteorological conditions.
- The aircraft encountered severe turbulence during a critical phase of flight (initial climb) while the passenger was in command.
- The presence of an active thunderstorm nearby contributed to the severe atmospheric instability and wind gusts.