Garbage HESLO Pilot Becomes Electric Powerline Hooker (Helitrans AS350B3 LN-OGA)
On 16 October 2021, Helitrans Airbus AS350B3 LN-OGA was tasked with moving large bags of rubbish as a Helicopter External Sling Load Operation (HESLO) in the Lofoten archipelago in Northern Norway. During a positioning sector the underslung load line cut three low voltage power lines.
The Accident Flight
The Norwegian Safety Investigation Authority (NSIA) explain in their safety investigation report (issued in Norwegian only on 30 August 2022) that the local waste management company had gathered rubbish at 15 waterfront locations which need transfer to 6 landfill sites. The task was estimated to take two days. It had been delayed by weather and only started on 15 October 2022 when 13 lifts were performed, carrying 3-6 bags on each. The pilot, who had 1,282 hours of flight experience, had spent a couple of hours planning the evening before using iPad application Air Nav Pro, maps and satellite data. It was not possible to do a ground recce at all the sites. At 10:00 on 16 October 2022 the helicopter again left Leknes Airport with the pilot, a load master and an employee of the waste company. The weather was better than the previous day, with good visibility and 10–15 knots south-easterly wind.
At the collection point, the loader and the customer’s representative left the helicopter, and the pilot began the flight by transporting the large bags to the predefined landfill at Banhammaren, at the southern tip of Mortsund. The flight route to the landfill was south of Mortsundholmen and the last part of the approach to Banhammaren was made from the south.
At the landfill site the pilot could released the load by electrically activating a hook at the lower end of the 15 m long line.
Three round trips were required to move 11 bags of rubbish. On the first two return sectors the pilot flew back the route they had flown outbound, south of Mortsundholmen. After the third load was delivered the helicopter needed to pick up the ground party and head to the next collection point. On this return flight the pilot choose to fly down the centre of a narrow strait between Mortsundholmen and Mortsund. Unbeknown to the pilot there were three 5.6 mm 230V powerlines across this strait at amount 55 feet (below the then 100 feet threshold for reporting aviation obstacles).
On the way through the strait, the commander spotted a power line pole on the north side of the strait and looked down through the helicopter’s floor window. In the window he saw three power lines…. Soon after, he felt a jerk… The captain quickly realized that the cargo line had caught in the power line and immediately opened the helicopter’s cargo hook with the electric release mechanism. The cargo line was disconnected and fell into the sea without causing any damage to property or people [it was later recovered by divers].
The NSIA note that a October 2020 regulation change in Norway will require obstacles >50 feet to be reported by July 2025.
NSIA were complementary about the pilot’s planning, but note that the mapping data naturally did not show the cables as they were not, nor needed to be, reported.
The decision to make the last departure across the strait between Mortsundholmen and Mortsund therefore becomes incomprehensible.
The pilot suggested that contributing factor to that choice of route “may have been that he had a different focus when the cargo flights had been completed and all that remained was to pick up the personnel”. The NSIA believes that, when he discovered the power line, the commander exercised good pilot judgment by dropping the cargo line, maintaining control and assessing the helicopter’s operational condition.
In this case, the commander was aware that only the cargo line had been in contact with the power line and chose to pick up the personnel before returning to Mortsundholmen. The NSIA believes that the correct measure following the incident would have been to land as quickly as possible for a visual inspection of the helicopter. This had provided a better verification of the helicopter’s technical condition.
The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn. ESPN-R has published this video and guidance in cooperation with EASA: You may also find these Aerossurance articles of interest:
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