What happened
On the afternoon of August 13, 1961, at the Spreitenbach airfield, a collision occurred between a De Havilland Chipmunk (registration HB-TUC) and a Mucha 100 glider (registration HB-638). The pilot of the Chipmunk, who had been performing glider towing duties earlier that day, decided to conduct a solo flight after glider operations had been suspended.
Instead of following the established takeoff direction of 100 degrees, the pilot initiated a movement from the northwest corner of the field toward the hangar. During this maneuver, the pilot attempted to move the aircraft using a technique of short hops rather than a standard taxi or takeoff. At the same time, a Mucha 100 glider had just landed on the same patch of grass. As the Chipmunk's tail leveled out, providing the pilot with forward visibility, the pilot realized the glider was in his path and attempted an aborted takeoff. However, with only approximately 50 meters of runway remaining, the Chipmunk struck the glider. The impact resulted in no fatalities or injuries, but the Mucha 100 was destroyed, and the Chipmunk sustained damage to its rear fuselage and left wing.
The investigation
The investigation examined the pilot's flight path, airfield regulations, and the specific maneuvers performed prior to impact. Investigators noted that the pilot's chosen direction was not in accordance with the posted airfield instructions. While the pilot claimed he intended to perform a solo flight, evidence from witnesses and physical tracks suggested he was attempting to move the aircraft to the hangar by "half-rolling, half-hopping."
Investigators also reviewed the pilot's visibility and reaction time. They established that once the aircraft's tail reached a horizontal position, the pilot's forward view should have been clear enough to identify the glider much earlier than the 50 meters claimed. Furthermore, the investigation noted that the pilot's chosen path was significantly different from a standard takeoff, which would have cleared the hangar by a much greater altitude.
Findings
- The pilot disregarded established airfield regulations regarding takeoff directions.
- The collision was caused by the unusual and careless method of taxiing the aircraft via short hops to reach the hangar.
- The pilot's lack of attention to the presence of the recently landed glider contributed to the inability to avoid the collision.