What happened
On October 24, 1965, a Beech 3 and5 Bonanza, registration HB-ECL, departed from the Eplatures airfield in La Chaux-de-Fonds, bound for Vichy, France. The aircraft, operated by UNAVIA A.G., was being flown by a single pilot.
Following takeoff, the aircraft entered an unusually steep climb. Approximately 600 meters from the runway threshold, the aircraft had already reached an altitude of 20 to 25 meters. After the pilot retracted the landing gear and flaps, the aircraft continued its steep ascent. However, at a distance of roughly 1,500 meters from the start of the takeoff, the aircraft began to sink and entered a left-hand turn. During this maneuver, the aircraft reached an altitude of approximately 120 to 140 meters before stalling. The aircraft pitched down at an angle of about 60 degrees and impacted a wooded area consisting of beech and fir trees. The impact caused the aircraft to catch fire, resulting in the total destruction of the airframe. The pilot sustained severe burns and was transported to a hospital in Lyon.
The investigation
The investigation examined the mechanical state of the aircraft, the pilot's experience, and the environmental conditions at the time of the accident. The aircraft had undergone a major overhaul less than a year prior, and its airworthiness certificate was valid. While maintenance records indicated that the airspeed indicator and variometer were worn and recommended for replacement, the pilot reported they had been functioning normally.
The investigation also considered whether mechanical failures, such as a sudden change in stabilizer position or seat movement, contributed to the accident. However, witnesses did not observe any sudden pitching of the aircraft prior to the stall, and the pilot had no memory of the immediate moments preceding the crash. Meteorological conditions were found to be favorable, with high visibility and minimal wind.
Findings
- The primary cause of the accident was a loss of airspeed during the climb.
- The aircraft's flight path involved an extremely steep angle of attack immediately following takeoff.
- The pilot was unable to recall the specific sequence of events leading to the stall.
- The impact with the terrain was tangential to the slope, which likely mitigated the severity of the impact for the pilot.