What happened
On May 26, 2015, a Robin DR380, registration HB-EUN, departed Lausanne-la-Blécherette, Switzerland, for a flight to Dole Tavaux, France. The flight was being conducted under Visual Flight Rules (VFR) for personal purposes. After passing near Mouthe, the pilot performed a right-hand turn and a subsequent left-hand turn while descending. During these maneuvers, the aircraft struck the terrain at an altitude of approximately 3,600 ft. The impact resulted in two fatalities and the destruction of the aircraft.
The investigation
Investigators examined the wreckage and found no evidence of mechanical failure prior to the impact. The engine was producing power, the flight controls were functional, and all four fuel tanks contained fuel. The aircraft struck the trees in a slight nose-down attitude, suggesting a controlled flight into terrain rather than a loss of control. Due to damage to the Garmin 100 GPS, flight data could not be retrieved, leaving the use of radio navigation equipment unconfirmed.
Meteorological data indicated heavy cloud cover consisting of cumulus and stratocumulus throughout the route. Specifically, the accident site and several peaks in the Jura massif were located within this cloud layer. Witnesses also reported fog in the area during the afternoon.
Regarding the pilot, the investigation noted a valid private pilot license with over 1,550 total flight hours. No medical factors were identified during the autopsy. However, no flight preparation documents, such as weather forecasts or navigation logs, were found on board. The only available navigation aid was an aeronautical chart with a straight line drawn between the departure and destination points.
Findings
- The primary cause of the accident was flying into terrain under unfavorable weather conditions that likely prevented safe VFR flight over the Jura mountains.
- The pilot likely lost visual references while approaching the mountains.
- Insufficient flight preparation prevented the pilot from adapting the flight plan to the encountered weather and terrain.
- A strong desire to reach the intended destination contributed to the decision to proceed despite the deteriorating conditions.