What happened
On July 23, 2008, a Robin DR400-RP, registration HB-KBM, departed from Münster airfield in Switzerland for a scenic Alpine tour. The aircraft was carrying the pilot and three passengers. Shortly after takeoff, the aircraft climbed steadily despite a strong headwind. However, approximately one kilometer after passing the runway end, the pilot initiated a left-hand turn toward the valley floor. This maneuver was executed much earlier and at a lower altitude than the standard flight pattern prescribed for the area. During the turn, the aircraft experienced significant turbulence due to gusty winds and began to oscillate between level flight and climbing. As the aircraft progressed through the turn, the bank angle increased sharply, and the aircraft eventually entered an uncontrolled state, pitching downward into the terrain. The impact resulted in four fatalities and the total destruction of the aircraft.
The investigation
Investigators examined the wreckage, flight data from an onboard EDM-700 device, and FLARM records. They also reviewed witness statements and photographs taken by a passenger during the flight. The investigation focused on the aircraft's weight and balance, the pilot's flight preparation, and the meteorological conditions at the time of the accident. Technical analysis of the propeller and engine components was conducted to rule out mechanical failure. While investigators noted several maintenance documentation discrepancies, they concluded that no pre-existing technical defects contributed to the crash.
Findings
- The aircraft's total mass and center of gravity were outside of the permitted limits for the specified flight.
- The pilot initiated the 180-degree turn approximately 1.5 kilometers earlier than the official flight pattern recommended for that location.
- The pilot's flight preparation was insufficient, specifically regarding the verification of the aircraft's weight and the review of the standard flight pattern.
- Inadequate flight tactics and the decision to execute a steep turn in turbulent, gusty conditions led to an aerodynamic stall.
- The high bank angle and abrupt control corrections necessitated by the wind caused the wing to lose lift, making the subsequent impact unavoidable.