What happened
On December 8, 2017, an Aquila AT01 was being ferried from Osnabrück-Atterheide to Braunschweig-Wolfsburg following scheduled maintenance. The pilot, a highly experienced professional with over 29,000 flight hours, departed Osnabrück-Atterheide at 12:15 PM, choosing a route south of the Wiehen and Weser mountains.
During the flight, weather conditions were highly variable. While some areas experienced good visibility, the route passed through areas of active showers and localized thunderstorms. The aircraft's flight path, as recorded by GPS, showed the plane following the terrain of the Weser valley, with altitudes dropping to approximately 800 feet above ground level near Hameln. At approximately 12:46 PM, the aircraft struck high vegetation on the western slope of the Ith hill, northeast of Bisperode. The impact resulted in the fatal injury of the pilot and the total destruction of the aircraft.
The investigation
The BFU examined the aircraft wreckage, engine components, and GPS data. Investigators analyzed meteorological reports from the German Weather Service, which indicated heavy snow or sleet showers and potential light to moderate icing in the area. The investigation also included a review of radar tracks and a specialized search for lightning strikes along the flight path.
Technical inspections of the Rotax 912 S3 engine revealed no mechanical failures or pre-existing damage to the crankshaft or valve train. While investigators found the fuel selector, ignition switch, and battery switches in the 'OFF' position at the wreckage, they determined these were likely the result of the high-energy impact and the aircraft's disintegration in the trees rather than intentional shutdown. No evidence of lightning strikes or electrical surges was found in the avionics or engine ignition system.
Findings
- The primary cause of the accident was controlled flight into terrain (CFIT) while operating in marginal visual meteorological conditions.
- The pilot was flying in a region where cloud ceilings were likely between 1,000 and 1,500 feet AMSL, and the aircraft was likely flying within clouds at the time of impact.
- The pilot's extreme experience may have contributed to a shift in personal perception of risk, leading to the decision to continue flight in deteriorating weather.
- The presence of wind turbines north of Hameln further restricted available maneuvering options at low altitudes.
- The aircraft was not equipped for instrument flight, and the flight was only authorized under Visual Flight Rules (VFR).