H2F Weekly Mayday #29

WEEK 29

H2F brings you the ‘helicopter mayday of the week’ with a short accident report summary. I tell you what happened. You think more about why it happened. We all learn from it. Because that’s what accident reporting is for.

TITLE

Automation failure during night SAR training leads to loss of control and impact with sea.

WHAT?

An S-92A was conducting a night Search and Rescue (SAR) training flight from Bergen. During an exercise using the helicopter’s automated SAR flight-control functions, it developed an uncontrolled nose-up pitch, accelerated backwards and struck the sea.

WHERE?

North Sea 2nm NW of Vestland County, Norway.

WHEN?

The helicopter struck the sea at approximately 19:40 local time on 28 February 2024. The Norwegian Safety Investigation Authority (NSIA) published its final report on 26 February 2026.

HOW?

The crew was practising locating and positioning over a training beacon using the Mark on Top (MOT) mode. During the manoeuvre, a technical failure in a circuit card within the pitch trim actuator caused the helicopter to continue pitching nose-up rather than following the expected automated profile.

As an initial increase in pitch was normal and expected, the developing malfunction was difficult to distinguish from correct system behaviour. When pitch subsequently increased to almost 30° nose-up the rotor thrust vector caused the helicopter to accelerate backwards until it impacted the sea. Investigators estimated that the pilots had three to six seconds in which to recognise and respond to the pitch increase becoming abnormal and intervening manually.

CONDITIONS?

The accident occurred at night over the sea with no external visual references. Conditions were VMC, with surface winds around 20kt, cloud base 1,400–1,900 ft and no external horizon. The low-level, low-speed SAR manoeuvre therefore depended heavily upon instruments and correct functioning and monitoring of the automated flight-control system.

Both pilots were experienced on S-92 but new to the SAR role. Investigators found no evidence that either failed to meet the training standard required.

OUTCOME?

The helicopter struck the sea, rapidly filled with water and capsized. The survivors entered the water and remained there for approximately 45 minutes before rescue. Cold exposure was a major threat, while difficulties were encountered operating personal locator beacons and other survival equipment in darkness and with cold hands.

The emergency flotation system had been armed but did not automatically deploy after electrical generator power was lost, while the inverted aircraft made the life-raft release handles inaccessible. One occupant died and five were injured.

WHY?

The investigation listed a technical failure combined with organisational and systemic causal factors:

• A circuit-card failure within the pitch trim actuator resulted in uncontrolled pitch increase while the helicopter was operating in MOT mode.
• The failure initially resembled normal automated behaviour. In darkness without external references, the crew had only seconds to detect from their instruments that the expected pitch-up had become abnormal.
• Training and procedures did not provide sufficient protection against this particular failure scenario.
• Six months before the accident, a new operator had assumed responsibility for SAR following an unusually compressed tender-to-start period. The timetable strained the organisation as it trained personnel and prepared equipment.
• The tender process had not adequately accounted for this safety risk or the power imbalance between customer and contractor, while regulatory oversight did not sufficiently challenge the operator’s Management of Change process.

REFERENCE?

Norwegian Safety Investigation Authority. (2026). Report on air accident in the sea west of Sotra, Vestland County, Norway on 28 February 2024 with Sikorsky S-92A, LN-OIJ, operated by Bristow Norway AS (Aviation Report 2026/03). NSIA.

Note:

Accident reports selected from the following open source databases: US NTSB; UK AAIB; Flight Safety Foundation’s Aviation Safety Network; Australia’s ATSB. Ireland’s AAIU; Taiwan’s TTSB; France’s BEA; Spain’s CIAIAC. Germany’s BFU.