What happened
On May 24, 2011, a Eurocopter SA 315B Lama, registration LN-ODD, was performing sling load operations in Haustreisdalen, Norway. The mission, operated by Nordlandsfly AS, involved transporting equipment and insulator chains to upgrade high-voltage power lines for a utility contractor.
During the delivery of a load to a specific mast, the helicopter's main rotor struck the outermost part of a mast traverse. This impact necessitated an immediate emergency landing in steep, sloping terrain. The landing was exceptionally violent, causing the aircraft to be destroyed. The pilot and one passenger both sustained serious injuries.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the sequence of events, the communication protocols between the crew and ground personnel, and the environmental conditions. The investigation noted that while a safety briefing and job analysis had been conducted prior to the flight, there were significant discrepancies in how the crew and ground staff understood communication responsibilities.
Investigators also looked into the physical setup of the operation, noting the use of a relatively short 13-meter longline and shorter straps than some ground personnel had expected. The investigation also reviewed the weather conditions, which included wind gusts up to 20 knots, and the pilot's use of mirrors and bubble windows to monitor the load.
Findings
- The primary cause of the accident was the failure to maintain sufficient safety margins between the helicopter and the power line structures.
- The pilot's visual reference was likely disturbed because a previously delivered load had rolled closer to the mast, potentially creating a misleading reference point during the subsequent delivery.
- There was a lack of unified communication procedures; the pilot and ground crew had different expectations regarding how instructions would be relayed to the cockpit.
- Wind and turbulence may have contributed to the aircraft drifting toward the structure.
- The use of short loadlines and straps made it more difficult to position the loads at a safe distance from the masts.
Safety action
Following the investigation, the NSIA issued a safety recommendation (SL 2013/06T) urging the Norwegian Civil Aviation Authority, through the Flight Safety Forum for Operators of On-shore Helicopters, to consider establishing an industry standard for minimum safety distances between helicopters and structures during flight operations.