What happened
On 6 September 2021, an Airbus Helicopters AS 350 B1, registration LN-ORJ, was conducting a power line inspection near the Gullesfjord in Kvæfjord municipality. The flight, operated by Heli-Team AS, was commissioned by Vesterålskraft Nett AS to inspect various poles and lines. During the mission, the crew intended to return to a specific electricity pole to document a fault. While performing a right-hand turn, the helicopter flew beneath an overhead power line spanning the fjord. The aircraft's rotor blade struck the cables, severing one of them. Despite the impact, the pilot managed to maintain control of the aircraft and performed a successful emergency landing. There were no injuries among the four people on board.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the circumstances leading to the collision, focusing on flight planning, visibility, and crew workload. The investigation looked into the lack of physical markings on the power line and the regulatory exemption granted by the Civil Aviation Authority (CAA) Norway, which had previously determined the line did not constitute an aviation obstacle. The NSIA also reviewed the division of responslamibilities on board, noting that a power company employee was assigned the role of map reader despite lacking specific training for that function. Additionally, the investigation analyzed the impact of weather conditions, specifically light drizzle, which obscured the pilot's view of the unmarked wires.
Findings
- The collision was primarily caused by the unmarked status of the power line, which made it extremely difficult to detect against the background.
- The pilot's limited experience with this specific type of line inspection and a high mental workload contributed to the incident.
- Inadequate mission planning and inaccuracies in the assignment increased the commander's workload.
- The use of an unqualified individual as a map reader created additional operational strain.
- Environmental factors, including drizzle and the lack of relative movement toward the line, hindered visual identification.
Safety action
- The NSIA recommended that CAA Norway reconsider its decision regarding exemptions for marking power lines and evaluate whether the Gullesfjord line should be physically marked.
- The NSIA also recommended that the CAA Norway follow up on other power lines that are currently exempt or partially exempt from marking obligations to ensure compliance with current regulations.