What happened
On September 12, 2008, a Bell 212 helicopter, registration D-HEPP, was engaged in firefighting operations near Vilares, Castelo Branco. The aircraft, operated by Helisul on behalf of the National Authority for Civil Protection (ANPC), was tasked with suppressing a forest fire along the Ocreza River.
After completing an initial water drop using a Bamby Bucket, the pilot began a descent toward a reservoir on the river to refill. During this maneuver, the aircraft'ably struck medium-voltage electrical cables that crossed the river. The impact caused an electrical discharge, shattered the right side of the cockpit roof, and damaged the main rotor blades. The pilot, who was not wearing a flight helmet, sustained minor abrasions to the lower back from falling debris. Despite the impact, the pilot maintained control and successfully landed the aircraft at the Castelo Branco base five minutes later. The collision caused the power lines to break, resulting in a local power outage and igniting vegetation on the riverbank.
The investigation
The GPIAAF investigation examined the flight path, the visibility conditions, and the availability of aeronautical information. Investigators found that the pilot was performing a steep descent along a slope, which significantly limited the field of view from the right-hand seat. Furthermore, visibility was compromised by heavy smoke from the ongoing wildfire.
The investigation also reviewed the operational data from the Castelo Branco Air Means Center (CMA). It was established that while the center was required to maintain maps of all available water points and associated obstacles, the specific map containing information about obstacles near the refueling site was unavailable at the time of the incident. Additionally, although the electrical line met the technical definition of an aeronautical obstacle under INAC regulations, the cables were not marked with any aviation warning lights or markers.
Findings
- The primary cause was the pilot's failure to detect the presence of the power lines in a timely manner.
- Reduced visibility due to smoke accumulation in the river valley hindered obstacle perception.
- The electrical cables were not marked with aviation warning lights, despite being classified as an obstacle.
- The aircraft's maneuver, involving a steep descent, placed the cables outside the pilot's primary field of view.
- There was a lack of adequate information regarding obstacles near the water source available to the pilot.
- The pilot was not wearing a flight helmet at the time of the impact.