Flight and Descent
After an uneventful flight from Nancy-Essey Airport, the crew began descent to Paris-Orly Airport and were cleared to reduce altitude to 6,000 feet. Weather conditions were marginal with poor visibility due to fog.
Loss of Control
Suddenly, the aircraft pitched down and entered an uncontrolled descent, reaching a rate of 16,000 feet per minute during the last 20 seconds. Out of control, the aircraft struck the metallic pylon of a high voltage power line and eventually crashed at an excessive speed of 630 km/h in an open field located in Machault, about 46 km southeast of Paris-Orly Airport.
Impact and Occupants
The aircraft disintegrated on impact. All 24 occupants were killed. The crew consisted of Bernard André (pilot), Eric Marquis (copilot), and Martine Loberteau.
Probable Cause
The official investigation determined that the electrical system failed in flight while the crew was flying under IFR mode in IMC conditions. Technical analysis and investigations were unable to determine with certainty the exact cause of the loss of control and the fatal descent. After eliminating various assumptions invalidated by the established facts and findings and after reviewing the results of flight tests conducted at its request, the commission assigned higher probability to the hypothesis that the electrical fault caused a loss of attitude reference and autopilot disconnect which would have occurred while the aircraft was configured 'out of trim' in a nose down attitude. In the absence of independent standby horizon, the crew had no usable attitude reference immediately available while the aircraft was in a high-speed dive.
Additional Findings
The following findings were reported:
- The loss of control occurred in icing conditions.
- A third person (non-crew) aged 18 was seated in the cockpit at the time of the accident.
- The aircraft's speed upon impact was 100 km/h above the maximum allowable speed certification.