What happened
On September 24, 2013, at 08:45 UTC, a Cessna RT421CP (registration N556MB) departed from Lyon-Bron Airport for a flight to Aix-les-Milles. The aircraft was operated for general aviation purposes, carrying a pilot and three passengers.
Immediately following rotation, the aircraft began to deviate to the left of the runway centerline. Witnesses and air traffic controllers observed the aircraft oscillating in roll and climbing at a very low rate. As the aircraft reached the end of the runway at an altitude of approximately 200 feet, it entered a sharp left turn and a steep nose-down attitude. Approximately 25 seconds after liftoff, the aircraft struck the ground within the airport perimeter, resulting in a post-crash fire. The impact and subsequent fire caused four fatalities and the total destruction of the aircraft.
The investigation
The BEA investigation focused on the aircraft's configuration and the pilot's actions. Investigators examined the wreckage, which showed the rudder trim was set to a "left nose" position. Technical examinations of the Pratt & Whitney Canada PT6A-135 turboprop engines and the fuel system revealed no mechanical failures or malfunctions prior to the impact. Both engines were found to be rotating at low power near idle at the time of impact.
The investigation also noted that the pilot was operating from the right-hand seat, a position that, while legal for this type, provides limited access to certain cockpit controls and the electric trim button. The pilot's experience on this specific high-performance, heavily motorized variant of the Cessna 421 was also evaluated.