What happened
On November 20, 1999, a Robin DR 400-180 F-GSBZ departed from the Valréas-Visan airfield, bound for Carpentras. Shortly after takeoff, while climbing through 1,500 feet, the engine stopped. The pilot attempted to restart the engine using the electric pump and by switching fuel tanks, but these efforts were unsuccessful.
As the aircraft flew over the Tulette area, the pilot identified an uncultivated, snow-covered field for an emergency landing. The subsequent impact with the ground was heavy, causing the nose gear and the right main landing gear to break away, while the left main gear collapsed under the fuselage. The aircraft slid through the snow before coming to a halt. There were no fatalities among the single occupant.
The investigation
The investigation focused on the cause of the engine failure and the meteorological conditions at the time of the flight. Investigators examined the wreckage, noting damage to the wing leading edges and the cockpit canopy. The engine and propeller were inspected; while the propeller blades were bent, the engine itself functioned correctly when tested on the ground, ruling out internal mechanical failure.
Investigators also reviewed meteorological data and witness accounts. Observations confirmed that the area was experiencing moderate to heavy snowfall with visibility reduced to between 500 meters and 2 kilometers. A photograph taken at the airfield just before departure showed the aircraft covered in snow, indicating that the aircraft had been stationary in freezing conditions.
Findings
- The pilot proceeded with the flight without updated or precise meteorological information for the specific area of operation.
- The pilot underestimated the weather conditions, which were unsuitable for VFR (Visual Flight Rules) flight and presented high risks of icing.
- The primary cause of the engine failure was likely the icing of the fuel tank vents. Because the aircraft had been parked under snow, the vents likely became obstructed by snow or ice, leading to a loss of fuel pressure and the subsequent unpriming of the fuel circuit.
- Carburetor icing may have also contributed to the engine failure, given the heavy snow and freezing temperatures.
- The low altitude at which the engine failed left the pilot with insufficient time to execute a controlled emergency landing.