What happened
On March 4, 2013, a Beechcraft Premier 1A, registration VP-CAZ, departed from Annemasse aerodrome for a short private flight to Geneva. The aircraft had been parked on the apron since the previous evening under freezing conditions, with temperatures at -2 °C and 98% humidity.
During the takeoff roll, the aircraft performed normally until rotation. Immediately after the wheels left the ground, the aircraft entered a high pitch attitude with a low rate of climb. The Ground Proximity Warning System (GPWS) issued multiple "Bank Angle" alerts as the aircraft began to oscillate violently between left and right banks. At an altitude of approximately 80 feet, the aircraft struck the roof of a house, subsequently impacting the ground. The impact caused the landing gear and left wing to separate from the fuselage. The aircraft slid approximately 100 meters before striking a garden wall and a shed, which triggered a post-crash fire. The accident resulted in two fatalities (the pilot and one passenger) and one serious injury to a second passenger.
The investigation
The BEA investigation focused on the aircraft's condition and the environmental factors present at the time of departure. Investigators examined the wreckage, the cockpit voice recorder (CVR), and the aircraft's anti-ice systems. The investigation established that while the pilot had activated the engine anti-ice systems and set the flaps to 10°, the aircraft's critical surfaces were contaminated with frost. The investigation also looked into the lack of de-icing capabilities at the Annemasse aerodrome and the pilot's awareness of the risks associated with ground frost.
Findings
- The primary cause of the accident was the presence of frost on the wing surfaces, which induced an aerodynamic stall immediately after takeoff.
- The pilot's insufficient awareness of the specific risks posed by ground frost led to the decision to depart without performing necessary de-icing procedures.
- The aircraft's anti-ice systems are designed for use in flight and are not effective for removing frost accumulated while the aircraft is parked on the ground.
- The Annemasse aerodrome lacked the necessary ground de-icing equipment to assist with such operations.
- The presence of an onboard ground-frost detection system could have potentially prevented the accident.