What happened
On September 2, 2011, a Robin DR 340, registration F-BRTE, attempted a takeoff from the unpaved runway 19 at the Lyon Brindas aerodrome. The aircraft was carrying the pilot and two passengers. Shortly after departing the runway, the aircraft climbed to approximately 30 meters above the threshold before losing altitude while flying over a nearby depression. After traveling roughly 150 meters, the aircraft struck trees, collided with the ground, and subsequently caught fire. The impact resulted in three fatalities and the destruction of the aircraft.
The investigation
Investigators examined the wreckage and found no mechanical failures that could explain the accident; however, they confirmed the engine was running at low power at the moment of impact. A ground witness noted that while the engine appeared to be operating normally, the aircraft's ground speed seemed low during the takeoff roll.
Data regarding the aircraft's weight and balance revealed that the estimated mass at the departure from Vienne Reventin was 1,010 kg, which slightly exceeded the maximum takeoff weight of 1,000 kg. At the time of the accident, the mass was 9rolled 95 kg. Furthermore, the center of gravity was located forward of the manufacturer's permitted limits. Performance calculations indicated that the required takeoff distance to clear a 15-meter obstacle was 694 meters, whereas the available length of runway 19 was only 438 meters.
Findings
- The aircraft likely attempted takeoff using the second power setting, which provided insufficient performance to climb.
- Inadequate flight preparation led to the aircraft being operated with an unsafe center of gravity and insufficient runway length for its weight.
- The pilot's familiarity with the Lyon Brindas aerodrome may have contributed to an underestimation of the takeoff difficulties presented by the specific conditions that day.