What happened
On April 22, 2007, a SF 25 C Falke motor glider, registration D-KEFI, crashed in the high Valbrembana region near Carona, Italy. The aircraft had departed from the Caiolo airfield approximately 30 minutes earlier for a local sightseeing flight. While flying at a very low altitude through the valley, the aircraft struck several large trees on a steep slope.
The impact caused the wings to detach from the fuselage. The remaining fuselage continued on a ballistic trajectory before striking the ground near the bed of the Brembo River. The accident resulted in two fatalities, involving both the pilot and the passenger.
The investigation
Investigators examined the wreckage and the flight path, noting that the aircraft's engine and propeller were functioning normally at the time of impact. The engine throttle was found in the full-power position, and the propeller blades had been cleanly sheared, indicating the engine was producing power when it hit the ground. There was no evidence of mechanical failure or engine malfunction.
The investigation focused on the terrain and the aircraft's performance. The valley floor rises significantly toward the east, with a gradient of approximately 12%. In contrast, the SF 25 C Falke has a maximum climb rate of only about 4.5% at its optimal climb speed. The investigation also noted that the pilot had not filed a flight plan and had not made any radio communications with air traffic services during the flight.
Findings
Analysis of the wreckage and the flight path suggests that the pilot likely entered an aerodynamic stall during a low-altitude maneuver. It is believed the pilot was flying at a low altitude and low speed when they noticed high-voltage power lines crossing the valley. In an attempt to clear the wires, the pilot likely executed a rapid pitch-up maneuver, which caused the airspeed to drop critically, leading to a stall. Due to the proximity to the terrain and trees, there was insufficient altitude to recover.
Contributing factors included:
- A lack of adequate flight planning, which resulted in insufficient knowledge of the local terrain and orographic features.
- An overestimation of the aircraft's climb performance relative to the steep terrain of the operating environment.