What happened
On the early morning of March 30, 2006, an Agusta A109E helicopter, registration LN-OLH, operated by Lufttransport AS, was performing a maritime pilot transfer mission. After hoisting a pilot from the vessel "Clipper Sky" in Herviksfjord, the crew proceeded southwest at approximately 500 feet. During the flight, the aircraft deviated from its intended course and flew over the island of Austre Bokn.
As the aircraft moved through the darkness, the pilot received a radio altimeter warning indicating terrain was approaching. In an instinctive attempt to avoid the ground, the pilot executed a sharp, steep climb. This maneuver caused the aircraft to lose control. The first officer, who was focused on communicating with another vessel, perceived the resulting vibrations and the pilot's distress as a mechanical emergency, specifically a potential tail rotor failure. Believing an emergency was underway, the first officer initiated an autorotation by reducing both engines to idle. The helicopter struck the sloping terrain of the island and overturned. All four occupants sustained injuries, with the pilot, first officer, hoist operator, and the maritime pilot all suffering significant harm.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the flight conditions, crew performance, and aircraft systems. The investigation established that the flight was being conducted under Visual Flight Rules (VFR), though conditions had transitioned into a state where instrument flight would have been more appropriate. The investigators also looked into the crew's workload, noting that the high-pressure environment of the hoisting operation had split the crew's attention across multiple independent tasks.
Findings
Several contributing factors led to the accident:
- The crew likely flew into a cloud layer, resulting in a loss of visual references and subsequent spatial disorientation for the pilot.
- The pilot's abrupt climb to avoid terrain caused the loss of aircraft control.
- The first officer's decision to initiate an autorotation was based on a misunderstanding of the situation and involved an improper engine setting (idle) that worsened the descent.
- There was a lack of effective Crew Resource Management (CRM), as the crew members were preoccupied with separate tasks and failed to communicate effectively regarding the flight path.
- The aircraft was flying at an altitude that provided insufficient safety margins for the terrain.
- The injuries sustained by the hoist operator and the maritime pilot were exacerbated because they were not wearing seat belts.
- The investigation also noted that the crew's performance may have been impacted by fatigue, as they had been flying multiple short missions throughout the night.