What happened
On April 13, 2005, a Robin DR400-180, registration F-GSBH, was conducting flight training maneuvers near Lormaison, France. The flight involved an instructor and three pilots, all of whom were recently licensed, as well as one additional passenger. The purpose of the flight was to practice engine failure procedures.
During the session, the crew performed several engine failure exercises, both within the airfield circuit and in the field. Following an initial period of training, one of the passengers took the controls for a subsequent flight. At approximately 13:45, the instructor announced the intention to perform two more engine failure exercises within the airfield circuit.
At approximately 14:00, witnesses observed the aircraft flying at a low altitude, descending, and performing a left-hand turn with a significant bank angle. Shortly after the aircraft disappeared behind a building, the sound of an impact was heard. The aircraft struck the ground at a steep nose-down attitude and high vertical velocity, resulting in four fatalities.
The investigation
The investigation focused on the wreckage, the engine condition, and the flight maneuvers. Investigators examined the aircraft's engine and found no mechanical anomalies; the engine was still rotating and delivering low power at the moment of impact. The fuel system was also checked, and while the tanks were empty upon discovery, the fuel analysis showed no contamination, and the carburetor settings were found to be at a full-rich mixture.
Radar data indicated that the aircraft's trajectory disappeared from radar at 13:55, suggesting the maneuver likely began at an altitude of approximately 900 feet. The investigation also considered the possibility of fuel exhaustion, but ruled it out because the engine was still producing power and the low-fuel warning would have alerted the crew prior to the exercise.
Findings
- The primary cause of the accident was a stall at low altitude occurring during an engine failure simulation.
- The decision to initiate the engine failure exercise at such a low altitude contributed to the accident.
- The high workload required to execute the emergency procedure, find a suitable landing site, and select a trajectory likely distracted the pilot from monitoring flight parameters.
- The instructor may have experienced reduced vigilance due to the repetitive nature of the exercises and confidence in the pilot's ability.
- The stall warning system did not provide sufficient warning to allow for recovery given the proximity to the ground.