What happened
On December 20, 1980, a Piper PA-30, registration HB-LAC, departed from Saint-Rambert d'Albon for a private VFR flight toward Annemasse. During the flight, the pilot encountered worsening weather characterized by low cloud ceilings, rain, and snow showers. Upon encountering these conditions, the pilot performed a 180-degree turn near the A 43 motorway junction. During or immediately after this maneuver, the aircraft entered instrument meteorological conditions (IMC). Witnesses observed the aircraft emerging from the clouds in pieces, with parts of the engine, wing, and tail separating and falling over a distance of nearly 2 km. The aircraft entered a spin and crashed, resulting in the death of the pilot.
The investigation
Investigators examined the wreckage distributed across the terrain, noting that eight major components were recovered. Technical analysis of the debris revealed that the outer portion of the left wing had failed due to upward bending and torsion, and the horizontal stabilizers had broken due to excessive downward aerodynamic loads. Radar data from Lyon-Satolas helped reconstruct the flight path, showing the aircraft did not fly over the intended VOR station and had its transponder turned off. The investigation also reviewed the pilot's training records, which indicated a lack of proficiency in instrument flight. Engines and propellers were inspected, but no mechanical failures or fuel issues were identified as the cause of the engine's behavior.
Findings
- The pilot entered IMC conditions while not qualified for instrument flight.
- The aircraft's structural failure was caused by extreme aerodynamic loads during uncontrolled maneuvers.
- The horizontal stabilizers broke due to an excessive nose-down force, likely resulting from an uncontrolled pitch or an inverted flight position.
- The left wing failure was caused by violent rolling forces at high speed.
- The pilot's lack of recent instrument training contributed to the loss of control during the weather transition.