WEEK 33
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
Lightning strike leading to loss of control, and partial loss of tail rotor.
WHAT?
A Sikorsky S-76C was operating a scheduled IFR passenger flight from Vancouver Harbour to Victoria Harbour with two pilots and 12 passengers on board. In cruise flight at 4,000 ft, the helicopter was struck by lightning. Part of the tail-rotor blade assembly separated and the helicopter entered an uncontrolled rapid descent, losing 3,144 ft before control was regained.
WHERE?
Approximately 10 NM northeast of Sidney, British Columbia, Canada.
WHEN?
24 October 2023. The final report was first published on 13 May 2026.
HOW?
While flying through cloud, there was a loud bang and bright flash. The lightning strike momentarily disabled the autopilot, flight director and all four electronic flight displays. Although, the displays quickly returned, only the captain’s displays provided valid information, and the autopilot did not automatically re-engage.
Following the strike, the captain took control from the first officer. By then the helicopter had climbed about 100 ft, slowed by 14 kt and developed increasing left bank and heading deviation. On taking control, the captain became spatially disoriented and the aircraft entered a steep descending turn, reaching an attitude of 63° left bank and 44° nose-down. It descended from 4,029 ft to 885 ft in 36 seconds. On emerging from cloud, the crew regained external visual references and recovered to straight and level flight.
CONDITIONS?
The flight was in IMC with heavy rain and turbulence. The available forecasts did not identify the specific conditions conducive to helicopter-induced lightning, so the crew had no warning of the threat. The strike was an unusually powerful positive cloud-to-ground discharge, probably triggered by the helicopter itself.
OUTCOME?
The helicopter sustained substantial damage but, after recovery from the unusual attitude, it remained controllable. On assessing their options, the crew continued VFR to Victoria Harbour and landed safely. All 14 occupants were uninjured.
Post-flight inspection revealed that the inboard tail-rotor blade assembly was missing (half the tail rotor). The rotor assembly had struck the horizontal stabilizer, main rotor blades and engine cowling after separating. Despite the resulting heavy vibration from tail-rotor imbalance, the pilots were able to maintain control.
WHY?
Lightning and structural failure: The helicopter encountered conditions conducive to helicopter triggered lightning. The positive strike’s peak current was 43% greater than the standard against which the tail-rotor blades had been tested, exceeding their certified design capability. The inboard tail-rotor blade assembly consequently failed and separated.
Immediately after the strike, the crew faced sudden instrument and automation disruption in IMC. Aircraft attitude changes and a transfer of control contributed to spatial disorientation. Despite recovering his flight displays, the captain was unable to reorient from the instruments and recovery occurred only after the helicopter emerged from cloud and external visual references were regained.
The lightning strike was almost certainly a profoundly startling and surprising event: an explosive bang and flash were immediately followed by the loss of the autopilot, flight director and all four primary displays in IMC. Although the investigation did not identify startle as a causal factor, a gap of 21 seconds before the captain assumed control, followed by spatial disorientation, are consistent with the cognitive disruption that startle and surprise can produce.
Startle-management techniques may therefore have relevance in this incident. A brief deliberate reset (controlling the immediate flight path, regulating the physiological response, establishing trustworthy attitude information and consciously rebuilding situational awareness before attempting diagnosis) might help crews recover cognitively from such an event. Research suggests these techniques can improve perceived stress management, SA and decision-making. However, this accident also illustrates the “startle paradox” – that the more urgent and startling the event, the harder it is to resist the impulse to act immediately and create the cognitive space needed to reset.
REFERENCE?
Transportation Safety Board of Canada. (2026). Lightning strike and loss of control, Helijet International Inc., Sikorsky S-76C++, C-GXHJ, Sidney, British Columbia, 24 October 2023 (Report A23P0136).
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.
