Background
On 29 September 1962, at approximately 1630 hours Central European Time, a Piper L-4 (registration HB-OCH) departed from Hangar North at Zurich-Kloten Airport for a training flight. The aircraft was owned and operated by the Motorfluggruppe Zürich of the Aero-Club Switzerland. The pilot, born in 1924, held professional pilot and flight instructor licenses and had approximately 2830 hours of flight experience. The other occupant, born in 1941, was a student pilot holding a learner permit for powered and glider aircraft.
The aircraft proceeded to the grass taxiway of runway 10/28, crossing taxiway 2, and stopped opposite the windsock—the designated area for engine warm-up. Weather conditions were: west wind, horizontal visibility 20 km, wind 4 knots from 240°, cloud cover 1/8 at 500 m, 3/8 at 2000 m, and 6/8 at 3000 m. Weather was not a factor in the accident.
Accident
A Canadair CL-44 freighter (operator Seaboard World Airlines, New York) had landed on runway 16 and was being guided by a marshaller via taxiway 1 to the parking position in front of the freight building. As the CL-44 turned onto the taxi line toward the building, after a temporary brake application and with somewhat increased power, its propeller blast reached the stationary Piper.
The occupants of the Piper noticed the danger through vibrations. The right wing of the Piper lifted, and the instructor attempted to roll away left with power. Simultaneously, the tail lifted, and the aircraft overturned over the engine, coming to rest inverted. The instructor and student were able to free themselves without assistance.
Aircraft and Injuries
The instructor sustained a slight bruise to the head but no incapacity for work. The aircraft suffered substantial damage: the right wing was severely twisted and externally damaged, with bent struts; the tail fin and rudder were damaged, with deformations extending into the fuselage structure; the propeller was broken on both sides of the hub; and the nose section had a dented oil cooler and deformed engine cowling. Estimated repair costs were approximately 3,000 Swiss francs, representing about 20% of the aircraft's value.
Conclusion
The accident occurred because the stationary training aircraft was struck by the propeller blast of a taxiing large aircraft. The investigation concluded that the local conditions at the airport contributed to the incident.