Introduction
On 20 May 2023, at approximately 10:31 local time, a Robin DR 400/180 R aircraft, registered HB-EQD, crashed in a steep, wooded slope at Les Combes-Dernier, in the municipality of Les Ponts-de-Martel, canton Neuchâtel, Switzerland. The accident occurred during a private visual flight rules (VFR) discovery flight. The aircraft was destroyed, and the three people on board suffered fatal injuries.
Aircraft and Flight Information
The aircraft was a single-engine, low-wing, four-seat Robin DR 400/180 R, serial number 1564, built in 1982 and imported to Switzerland that same year. It was powered by a Lycoming O-360-A3A four-cylinder air-cooled engine. The operator and owner was the Aéro-Club des Montagnes Neuchâteloise, based at Les Eplatures airport (LSGC). The pilot, a Swiss citizen born in 1951, held a Private Pilot Licence (Aeroplane) issued by the European Union Aviation Safety Agency (EASA) and had accumulated 1141 hours 19 minutes total flight time, with 3 hours 42 minutes in the previous 90 days. His experience on the type was not precisely known, but witnesses reported he was familiar with the aircraft.
The flight was a 30-minute discovery flight with two passengers, intending to overfly the Creux-du-Van area. The pilot arrived at Les Eplatures around 09:00, moved the aircraft from a closed hangar to the apron with assistance, and prepared for the flight. The aircraft was refueled with 40 litres of AVGAS 100LL at 09:50. Takeoff from runway 06 occurred at 10:18, followed by a right turn toward Les Brenets.
Accident Sequence
At 10:21, the pilot reported overflying Les Brenets at approximately 4000 ft AMSL and indicated his intention to proceed to Creux-du-Van. Radar tracking showed the aircraft leaving the control zone and heading south. Due to terrain, radar coverage became intermittent after 10:27:03. The aircraft was again detected at 10:29:17, flying northwest at 4100 ft AMSL with a ground speed of 96 knots. It reached 4600 ft at 10:29:54 and continued climbing to 4800 ft before beginning a descent.
Three observers located near the Combes-Dernier area, below the only farm in the area, heard the aircraft overhead with an irregular engine noise but did not initially see it. Observer A saw the aircraft perform a downward looping-like maneuver before entering a left-hand descending spiral. After passing a ridge, the aircraft crashed nose-down into the forest. Observers B and C saw the aircraft only after the spiral began. Observer C noted the engine noise decreased significantly during the spiral descent.
The aircraft impacted at 10:31. It was destroyed, and the three occupants sustained fatal injuries. The emergency locator beacon activated, but its signal did not contain precise position information. There was no post-impact fire, though some fuel leakage caused minor soil pollution.
Post-Impact Observations
The aircraft was destroyed in the crash. Light damage occurred to the surrounding forest. The aircraft's mass and center of gravity were within approved limits, and fuel quantity was sufficient for the planned flight. The last scheduled maintenance, an annual/100-hour inspection, was completed and certified on 5 May 2023 at 3066:11 hours time since new, using the EASA minimum inspection programme. The nature of the accident was classified as a failure of a system other than the engine, though the specific failed system was not identified in the report.