What happened
On June 4, 2001, a Cap 10B aircraft, registration HB-SAO, crashed into a field in the extension of runway 05 at the Biel-Kappelen airfield. The aircraft was occupied by a flight instructor and a student pilot. Witnesses observed the aircraft taking off and flying at a low altitude for an extended period to build speed. Shortly after passing a local building, the aircraft was abruptly pulled upward into a steep climb. This maneuver caused the aircraft to lose speed rapidly, leading to a lateral roll and a subsequent crash at an altitude of approximately 60 meters. Both occupants sustained fatal injuries, and the aircraft was destroyed.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the wreckage and interviewed witnesses. Technical inspections of the HB-SAO revealed that the engine was producing significant power at the moment of impact, as evidenced by the condition of the propeller and manifold pressure readings. Investigators also examined a broken control cable connection, determining it had failed due to a single instance of excessive force (overstress) rather than fatigue. Medical examinations of the occupants found no evidence of impairment due to alcohol, drugs, or sudden medical emergencies that would have caused loss of consciousness. A reconstruction flight confirmed that the aircraft's speed during the actual takeoff was significantly lower than the manufacturer's recommended speeds for climbing.
Findings
- The aircraft was operating within its weight and balance limits for Category A.
- The takeoff involved an inadequate flight tactic where the pilot attempted a steep climb without sufficient airspeed.
- The landing flaps remained extended at 15 degrees during the maneuver, which increased induced drag and hindered acceleration.
- As the aircraft left ground effect, the lack of kinetic energy caused a rapid loss of airspeed and longitudinal instability.
- No mechanical or technical failures were identified as contributing factors to the accident.