What happened
On 17 June 2017, a Eurocopter AS 350 B3, registration F-HETH, was engaged in firefighting operations near Garrovillas de Alconétar, Spain. The aircraft had been dispatched from the Hoyos base to combat a fire in the region. After disembarking a firefighting squad at approximately 21:25, the pilot flew to a nearby reservoir to replenish the water bucket.
While returning to the reservoir for a second water loading attempt, the pilot encountered power lines directly in the flight path. Despite an immediate evasive maneuver involving a sharp bank and full collective input, the rotor blades and a cable cutter struck the lines. The impact severed three conductors, causing a power outage for the local municipality. The pilot performed an emergency landing, and while the pilot was not injured, the aircraft sustained heavy damage, including dents and scrapes to the blades, nose, and cowling.
The investigation
The CIAIAC investigation examined the flight path, meteorological conditions, and maintenance records. GPS data revealed that while the pilot performed a reconnaissance flight of the fire area, he did not specifically scout the water loading area for obstacles, as required by the operator's manual.
Investigators also analyzed the lighting and visibility conditions. At the time of the second approach, the sun was near sunset, leaving the flight path in shadow. This, combined with smoke from the active fire and strong winds, significantly reduced visibility. The investigation also reviewed the effectiveness of the installed cable cutter, which helped mitigate the impact and aided the pilot's survival.
Findings
- The primary cause of the accident was the execution of a water loading maneuver in an area that had not been previously reconnoitered.
- Low visibility at the accident site, caused by smoke and approaching dusk, prevented the timely detection of the lines.
- The power lines lacked adequate lighting or marking to make them visible in the shaded, smoky environment.
- The pilot failed to follow the operator's procedures regarding the scouting of approach and takeoff paths for obstacles.