Aircraft and Personnel
The incident involved a Convair CV-440, registration HB-IMF, owned and operated by Swissair, and a Cessna 172, registration HB-CPY, owned by the Aero-Club of Switzerland, Geneva section. The Cessna was occupied by an electrical mechanic employed by Pilatus Air Service, who was performing radio compass and communication checks. The Convair was under the supervision of a mechanic holding a run-up license for the type.
Weather Conditions
Weather at the time included west wind at 20 knots from 220°, visibility 15 km, scattered clouds, and temperature 10°C.
Accident Sequence
On the morning of 7 November 1963, the electrical mechanic completed his checks on the Cessna, which was positioned on the test area in front of the Swissair hangar. The Convair was undergoing engine run-ups on the braking area, oriented into the wind due to the strong westerly wind. After finishing his work, the mechanic taxied the Cessna towards the Pilatus hangar, crossing the longitudinal axis of the Convair approximately 25 to 30 meters behind its tail. At that moment, the Convair's left engine was at 2200 RPM and the right at 1500 RPM. The Cessna was caught by the propeller slipstream, experienced a sudden left yaw, and overturned onto its back over the left wing tip and propeller hub. The engine stopped. The mechanic sustained only minor scratches and neck pain, requiring no medical treatment.
Damage
The Cessna sustained severe damage: fuselage compressed, right wing heavily deformed, left wing slightly deformed, tail surfaces demolished, propeller bent, landing gear bent. Estimated damage 80–90% of value. The Convair was not damaged.
Concluding Remarks
The investigation concluded that the accident occurred because the Cessna crossed the propeller slipstream of the Convair at too close a distance. The strong wind contributed to the accident.