Helitrans AS350 B3 Incident at Mortsundholmen (LN-OGA)

Incident Overview and Aircraft Details On 16 October 2021, at 11:08 local time, an aviation incident occurred at Mortsundholmen in Vestvågøy municipality, Nordland, Norway. The aircraft involved was an Airbus Helicopters AS350 B3, registration LN-OGA, manufactured in 2020 and powered by a Safran Helicopter Engines Arriel 2D engine. The helicopter was operated by Helitrans AS. The flight was a commercial operation conducted in visual meteorological conditions (VMC) with variable winds of 10–15 knots, temperatures between 5–10 degrees, and sunny skies. One person was on board, and there were no personal injuries or damage to the aircraft. ## Operational Context and Flight Sequence The incident occurred during a two-day waste transport mission for Lofoten Avfallsselskap, which involved collecting garbage in large bags from 15 collection points along the Lofoten coastline and transporting them to six predefined landfills. The mission had been delayed due to weather conditions. On the first day, 15 October, the crew completed 13 transport trips. On the second day, the helicopter departed Leknes Airport (ENLK) at approximately 10:00 with three people on board: the pilot-in-command, a load handler, and a representative from Lofoten Avfallsselskap. The pilot flew directly to the first collection point south of Bårdsundtinden, east of Mortsund. After the load handler and customer representative disembarked, the pilot conducted three transport trips to the landfill at Banhammaren, located on the southern tip of Mortsund. The route to the landfill was planned south of Mortsundholmen, with the final approach from the south. The pilot used a 15-meter load line with an electrically operated hook to release the garbage bags at the landfill. ## Incident Description After completing the third transport trip, the pilot decided to take a different route back to the collection point to retrieve the load handler and customer representative. Instead of flying south of Mortsundholmen as in previous trips, he chose to fly over the narrow strait between Mortsundholmen and Mortsund. Buildings were present on both sides of the strait, and a power line ran at an incline from Mortsund down to Mortsundholmen. The pilot flew the helicopter in a northeasterly direction, approximately mid-strait, with the load line connected. While crossing the strait, the pilot spotted a power line pole on the northern side and looked down through the helicopter's floor window, where he saw three power lines hanging vertically. Immediately after, he felt a jerk in the helicopter. The pilot quickly realized that the load line had caught on the power line and immediately opened the helicopter's load hook using the electric release mechanism. The load line detached and fell into the sea without causing damage to property or persons. The pilot established the helicopter in a high hover and assessed the situation. Finding nothing abnormal, he continued the flight to retrieve the load handler and customer. After picking up the personnel, the pilot returned to Mortsundholmen and landed south of the buildings, where he notified the property owner, the power company, and the helicopter company about the incident. The damage was limited to the power line over the strait, which was cut. There were no personal injuries, environmental damage, or damage to the helicopter. The load line was later recovered by divers. ## Power Line Details and Regulatory Context The cut power line was a 230V line supplying two customers. The distance between the poles was approximately 95 meters, and the height of the power line over the strait was approximately 17 meters. This height was indicated by a warning sign for ship traffic in the opposite direction of the helicopter's path, located at the water's edge. The power line consisted of three uninsulated copper conductors with a diameter of 5.6 mm, mounted vertically on an 8-meter-high pole. Customers received power back at 17:05, approximately six hours after the incident. The Norwegian Accident Investigation Board (SHK) checked several mapping websites, including Geonorge.no, Kart.gulesider.no, Norgeskart.no, and NVE thematic maps for grid installations. The power line pole was visible on Geonorge.no and Norgeskart.no, but the power line between the poles was not visible on any of the maps. The power line was also not detectable on satellite images. The power line was not registered as an aviation obstacle because the power company had assumed it was in an industrial area where the reporting threshold was 30 meters, according to regulation 15 July 2014 No. 980 on reporting, registration, and marking of aviation obstacles. Regulation 16 October 2020 No. 2068 amending the regulation on reporting, registration, and marking of aviation obstacles changes the definition of when an energized power line must be reported. The new mandatory reporting height for power lines is 15 meters. The power line that was cut will be required to be reported as an aviation obstacle by 1 July 2025, according to the amending regulation. ## Aircraft Equipment The helicopter was equipped with its own certified under-slung hook under the belly, which could be opened both electrically and hydromechanically from the cockpit. At the lower end of the synthetic load line, an additional load hook was installed that could be opened electrically with a switch in the cockpit.