What happened
On January 25, 2003, a Socata MS885 Rallye, registration F-BKLK, departed from Lyon Corbas for a flight to Grenoble Saint-Geoirs. The flight was intended to transport the pilot and two passengers to an annual mountain pilot meeting.
During the flight, the aircraft's trajectory deviated significantly from its direct route. Radar tracking showed the aircraft heading southeast before making sharp turns toward the east and then south near Saint-Jean de Bourcal. Witnesses on the ground observed the aircraft flying at extremely low altitudes, appearing to "flirt" with the treetops and maneuvering between the terrain and a low cloud ceiling. Eventually, the aircraft struck a clearing in Lieudieu with a high pitch and right bank angle. The impact resulted in three fatalities and the total destruction of the aircraft.
The investigation
The investigation focused on the flight conditions and the aircraft's equipment. Investigators established that the aircraft was not equipped for instrument flight (IFR) and lacked a GPS receiver or transponder. The aircraft utilized a Venturi system to power its gyroscopic instruments, a system that is unreliable during maneuvers or in icing conditions.
Meteorological data at the crash site indicated very low visibility, with stratus clouds as low as 60 feet and high humidity. Witnesses noted that the treetops were covered in frost, suggesting icing conditions. The investigation also examined the pilot's decision-making, noting that while the pilot held an IFR rating, the aircraft itself was not capable of such operations.