History of the Flight
On Friday 3 May 2024, a Bell 206B helicopter registered F-BXPF was conducting a mosquito eradication flight near Peyriac-de-Mer, France. The pilot, seated in the right-hand seat, took off at approximately 09:40 from a helicopter landing site (HLS) for the fifth spray flight of the day. After treating an area close to the HLS and crossing Bages lake, the pilot treated additional areas before beginning the return transit across the lake to the HLS.
Data from the GTN650 computer and GNSS recordings indicate that the helicopter initially climbed to a height of about 60 m, then flew level at that height for approximately 20 seconds. It then began a smooth descent with an average vertical speed of 350 ft/min. After descending for roughly 35 seconds, the helicopter struck the water surface and sank. The pilot managed to unfasten his seatbelt and exit through the broken canopy, and was picked up by a fisherman who was close to the accident site.
Additional Information
Wreckage and Site
The wreckage was found lying on its left side, partially submerged in Bages lake at a depth of about two metres. It was recovered by helicopter three days later on 6 May 2024. The wreckage had drifted with the current, and not all parts were found. The airframe had very little damage; the tail boom rupture resulted from the blades contacting the water. Examination of the tail rotor, cyclic, and collective pitch controls confirmed they were continuous at the time of impact. The fuel system was continuous, with no contamination in the filter, and sufficient fuel remained for continued flight. A salt deposit was observed in the bottom of the fuel tank.
Engine and Fuel Examination
The engine was removed and disassembled at a manufacturer-approved service centre. It was found to have been operating and delivering power at impact, but damage and corrosion from saltwater immersion prevented determination of power output. Fuel samples from the helicopter and refueling tank showed characteristics matching the specified fuel, with no contamination detected. The deposit was primarily salt, likely from water present in the tank prior to the accident.
Helicopter Information
The Bell 206B is a five-seat helicopter with a Rolls-Royce M250-C20B engine. Its instrument panel includes airspeed, vertical speed, altimeter, artificial horizon, and engine parameter instruments. It was not equipped with an autopilot. The helicopter was dry-leased by the operator from 25 March 2024 for seven months with a 100-hour limit.
Flight Data Analysis
GNSS data from the Garmin GTN650 and the pilot's mobile phone applications (SDVFR and Field Navigator) were consistent. Analysis of previous flights showed positioning altitudes of 300–400 ft and transit altitudes of 200–300 ft or around 100 ft for short legs. The accident flight's crossing of the lake earlier in the day was at 25–100 ft. The pilot's phone showed no non-flight application usage during the accident flight. A camera recovered from the wreckage did not contain the end of the flight.
Meteorological Conditions
Météo-France estimated conditions at the accident site as: wind from 265° at 4 kt gusting 8 kt, CAVOK, temperature 14°C, dew point 4°C. The sun azimuth was 92.5° with elevation 26.2°.
Pilot Information
The 53-year-old pilot held a Commercial Pilot License (CPL(H)) with a Bell 206 rating. He had about 6,000 flight hours total, including 240 hours on type and 84 hours in the previous three months. Most experience was aerial work on the Bell 47.
Statements
The pilot stated it was the first day of the mission and he did not feel tired. He noted a slight humming sound from the rear during the positioning flight. Before each flight, he topped up fuel and product. After the fourth flight, he had a short break and placed a camera on the spray booms. He reported that after landing, an amber 'TRANS PRESS' light would illuminate but extinguish when pressurized, which he considered normal.
During the fifth flight, after treating fields, he began crossing the lake back to the HLS. He estimated flying at about 20 m height and 80 kt. While monitoring his position relative to a no-fly zone near an island using his mobile phone, he felt a strong jolt, saw no warnings, then the helicopter nosed down and struck the water. He did not recall intentionally descending. He noted that the smaller phone screen forced him to lean forward, and that on a previous flight without a tablet, the helicopter had begun to descend while he leaned toward the phone.
The fisherman stated he heard the helicopter and saw it flying low over water. When he looked again, it was in a dive and struck the water about three seconds later. He was 50 m away and came to the pilot's aid.
Operator Information
The operator had recently added agricultural spraying and leased F-BXPF for this activity. The Operations Manual specified VFR with sight of ground, treatment height of 1–5 m above vegetation, and minimum transit height of 500 ft except for reconnaissance. The operator planned to use an EFB but had not acquired hardware; pending that, pilots were provided a tablet with a tracking application.
Conclusions
The pilot unintentionally initiated and controlled a continuous descent at an average vertical speed of 350 ft/min for about 35 seconds from 60 m, while believing he was in level flight at about 20 m, leading to collision with the water. Contributing factors included: increased attention to the telephone while flying low over a surface with few visual references; use of an unusual navigation aid requiring the pilot to lean forward, possibly inducing nose-down input; and the decision to transit at low height, reducing safety margins.