What happened
On July 25, 2008, a FK9 Mark IV ultralight aircraft, registered as D-MFFO, was conducting a private VFR flight from Germany to Kägiswil, Switzerland. After landing earlier that day in Fricktal-Schupfart to refuel, the pilot departed at 16:08 local time, heading south toward the destination.
During the flight, the pilot communicated with Alpnach Tower, requesting instructions for the approach to Kägiswil. While flying over the Alpnach airfield, the pilot appeared preoccupied with adjusting the transponder code. As the aircraft approached the destination, witnesses observed the aircraft flying a much lower and tighter pattern than the published procedures required. While executing a left turn into the downwind leg for runway 03, the aircraft entered a steep, descending spiral. The aircraft struck a meadow at the foot of a mountain slope near Sarnel, resulting in the death of the pilot and the total destruction of the aircraft by fire.
The investigation
The investigation established that the aircraft's weight and center of gravity were within permissible limits and that there were no mechanical failures contributing to the accident. The investigation also noted that the pilot's flight logs were destroyed, making it difficult to determine total experience, though recent training was estimated at approximately 15 hours within the previous six months.
Investigators examined the pilot's flight path and noted a pattern of deviating from published traffic patterns. Earlier in the day, at Fricktal-Schupfart, the pilot had flown a significantly lower and shorter approach than prescribed. This tendency was repeated at Kägiswil, where the pilot chose a path much closer to the terrain and the runway threshold than the visual approach chart suggested.
Findings
- The accident was caused by a loss of control leading to ground impact.
- The pilot chose an unfavorable flight path during the approach, significantly deviating from the published traffic pattern.
- The pilot's training and recent flight experience were insufficient for navigating complex airspace and challenging mountainous topography.
- The aircraft was flying at a very low altitude relative to the terrain, leaving no margin for error when the aircraft entered a stall during a tight turn.