What happened
On 28 February 2024, a Sikorsky S-92A helicopter, registration LN-OIJ, crashed into the sea approximately 3.5 nautical miles west of Sotra, Norway. The aircraft, operated by Bristow Norway AS, was performing a Search and Rescue (SAR) training mission involving the retrieval of a training beacon. During the maneuver, the crew utilized the "Mark on Top" automatic flight control mode to align the aircraft with the wind and descend. During this process, the helicopter experienced an excessive nose-up pitch that was not corrected in time. The aircraft reached a pitch attitude of roughly 30 degrees, causing it to enter a Vortex Ring State, a condition from which the crew could not recover. The helicopter impacted the water, causing it to capsize and sink quickly. While five of the six crew members managed to evacuate the cabin, one fatality occurred when a crew member was found lifeless in the water.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the mechanical, operational, and organizational factors surrounding the accident. The investigation focused on the flight recorders, the wreckage, and the aircraft's automated systems. Investigators analyzed the behavior of the pitch trim actuator and the crew's ability to recognize and respond to the abnormal flight attitude. The inquiry also looked into the training protocols of the operator during a period of significant organizational expansion and the procurement process used by the client, Equinor ASA, for SAR services.
Findings
Technical analysis suggests that the primary cause of the loss of control was likely a failure of the pitch trim actuator, a non-redundant component. This failure induced the extreme pitch-up attitude. The investigation found that the crew had a very brief window of three to six seconds to identify and correct the abnormal attitude, which was not achieved.
Furthermore, the investigation identified several contributing organizational factors:
- The operator's training regime was undergoing a major transition during a period of rapid expansion, which may have led to variations in how pilots understood specific SAR operational tasks.
- Ambiguous procedures regarding task sharing during critical flight phases may have increased operational risk.
- The tender process for SAR services focused heavily on meeting start-up deadlines, potentially overlooking the safety implications of a compressed transition period between operators.
- The emergency flotation system failed to deploy automatically, and the crew encountered difficulties releasing life rafts and activating personal locator beacons in the dark, cold environment.
Safety action
The NSIA issued several safety recommendations, including an immediate directive to Sikorsky to ensure pilots are fully aware of how the autopilot system behaves in certain modes. Other recommendations addressed the need for better digital arrival-time estimation tools for rescue coordinators and the necessity for clearer guidance from EASA regarding airworthiness compliance for helicopter design changes.