1978 Bücker 131-150 Accident at Epiquerez (HB-UVA)

Incident Overview and Flight Details On October 7, 1978, two pilots departed from the Porrentruy airfield in a Bücker 131-150 Jungmann, registration HB-UVA, for a private flight to Courtelary. The aircraft, a 1939-built biplane modified in 1975 with a Lycoming IO-320-E2A engine, was owned by the AéCS, Groupe de vol à moteur, Porrentruy. The flight was conducted under visual flight rules (VFR) during the day. The aircraft was not equipped with a radio, so one pilot telephoned the destination airfield to announce their arrival. The takeoff occurred on runway 07, and the exact departure time was not recorded by the pilots, as was customary at Porrentruy. The aircraft was last observed at 14:55 local time near Epiquerez, flying at an estimated altitude of 10.30 meters. Witnesses reported the aircraft was flying stably but very slowly, with the engine operating normally. Suddenly, the aircraft pitched forward, executed a quarter turn to the left around its longitudinal axis, and struck the ground nose-down at an angle of approximately 30 degrees. A fire broke out immediately, and the aircraft was completely destroyed. The accident occurred on the territory of the commune of Epiquerez/JU, at an altitude of 885 meters above sea level. The coordinates were 570'600/241'950 on the Swiss national map 1:50,000, sheet 222 (Clos du Doubs). Both occupants were killed, and the aircraft was destroyed. Other damages were insignificant. A witness attempted to rescue the rear-seat pilot, who was still alive, but the intensity of the fire forced the witness to retreat. The rear-seat pilot survived briefly but died from the injuries sustained in the accident. The front-seat pilot was killed instantly. The cause of the accident was determined to be a loss of speed with the onset of a spin at low altitude for undetermined reasons.