1964 De Havilland DH-82 Tiger Moth accident at Courtelary (HB-UBH)

Investigation and aircraft details The Federal Commission for Aircraft Accident Investigations opened a preliminary inquiry on 31 May 1964. The aircraft involved was a De Havilland DH-82 Tiger Moth registered HB-UBH, owned and operated by the Groupe de vol à voile du Jura-Sud. Its maximum weight was 830 kg, and its certificate of airworthiness, issued on 5 April 1963, was valid until 10 April 1965. The pilot, born in 1937, held a private pilot licence issued on 11 April 1960, valid until 26 March 1966, with a towing extension, and a glider pilot licence issued on 11 September 1958, valid until 26 March 1966. The report stated approximately 120 powered flight hours with 600 takeoffs and approximately 60 glider flight hours with 140 takeoffs. ## Flight and accident At about 1315 HEC, the pilot departed from Courtelary aerodrome in HB-UBH to tow glider Mucha HB-614. The wind had changed around 1230 hours, shifting from the bise to a westerly direction toward the runway. After full throttle and a run of about 100 m, the pilot felt a strong crosswind from the south pushing the aircraft toward the hangar side. He attempted to bank left to maintain the runway centreline, but the left lower wing threatened to strike the ground. The pilot released the glider and attempted to take off. The aircraft’s landing gear struck a glider parked at the edge of the airfield. After the collision, the aircraft lost control, banked left, and began descending. The pilot cut the ignition, and the aircraft came to rest heavily in a wheat field bordering the runway. ## Damage and findings No person was injured. HB-UBH sustained major damage, with both left wings broken and the engine torn off. The estimated repair cost was about Fr. 12,000. A parked glider, HB-612, an L-Spatz 55, sustained a broken wing; the damaged party was the Groupe de vol à voile de Bienne, with damage estimated at Fr. 6,500. The investigation concluded that a sudden change in wind direction displaced the towing aircraft, and the pilot was unable to maintain the departure alignment. The report stated that the pilot realised too late that the aircraft was heading toward a parked glider and waited too long to release the glider. While attempting to clear the obstacle, the landing gear struck it, causing loss of control and a heavy landing in the wheat field.