What happened
On May 11, 2003, a SOCATA TB-200, registration HB-KDN, departed from Mollis airfield for a private sightseeing flight through the Alps. The aircraft was carrying the pilot and two passengers. The flight was intended to traverse the Flüela and Julier passes.
During the flight, weather conditions in the Grisons region deteriorated significantly. While the pilot had initially departed under favorable conditions, the onset of clouds and rain made the planned route through the Julier Pass impossible under Visual Flight Rules (VFR). At approximately 15:25, an emergency locator transmitter (ELT) signal was detected near the Julier Pass. Following a search, a REGA helicopter located the wreckage at Valletta Schlattain, near Piz Schlattain, at 19:37. All three occupants of the aircraft were killed upon impact.
The investigation
Investigators examined the wreckage and the flight's operational history. The aircraft's last known GPS position was on the southern side of the Valletta Schlattain valley, while the wreckage was found on the northern side. Analysis of the impact marks on the snow and the deformation of the engine components suggested the aircraft struck the ground in a descending turn, likely attempting a 180-degree maneuver to return to safer airspace.
Technical examinations of the engine, fuel system, and flight controls revealed no pre-existing mechanical failures. The aircraft was operating under a provisional certificate of airworthiness. The investigation also reviewed weather reports from MeteoSchweiz and eyewitness accounts from other pilots, which confirmed that the weather had become unstable with low ceilings and reduced visibility in the mountain passes.
Findings
- The primary cause of the accident was a collision with terrain following a loss of control caused by inappropriate mountain flying tactics.
- The pilot's relatively limited flight experience contributed to the accident.
- Weather conditions in the Alps deteriorated faster than forecasted, making the Julier Pass impassable for VFR flight.
- The aircraft was flying in the lee side of the valley, subject to the effects of the south-southwest wind.