WEEK 38
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
Loss of visual references in whiteout leads to fatal CFIT on frozen lake.
WHAT?
A Bell 206 conducting a single-pilot aerial geophysical survey suffered a loss of control following inadvertent entry into instrument meteorological conditions (IIMC). The helicopter was carrying a survey sensor suspended on a 300-ft longline.
WHERE?
Lake Athabasca, Alberta, Canada.
WHEN?
Accident: 12 February 2024. Final report published: 26 August 2026.
HOW?
During survey operations, the pilot was advised that weather was deteriorating at the departure airport. After completing the current survey line, the pilot returned towards the airport.
Approaching Runway 22, visibility deteriorated to approximately ¼ mile in blowing snow. Despite activating the runway lights, the pilot could not see the runway. Shortly afterwards, the pilot reported accumulating ice, loss of all visual references, and being uncertain of the helicopter’s position.
After reversing course, following advice from another pilot on the ground, the aircraft headed towards Lake Athabasca in the hope of regaining visual references and potentially landing near the shoreline. However, instead of following the shoreline, the helicopter flew out over the featureless, snow-covered lake. Approximately two minutes before impact, the helicopter was flying at just 27 kt groundspeed. The pilot subsequently reported releasing the external load, losing control and entering a spin. The helicopter struck the frozen lake in a nose-down, right-banked attitude.
CONDITIONS?
An overcast sky produced diffuse lighting over uniformly snow-covered terrain, eliminating shadows and contrast. These flat light conditions severely degraded the perception of height, distance and closure rate.
Snow squalls further reduced visibility, producing whiteout conditions in which the horizon and surface references became indistinguishable. The 300-ft suspended load also constrained the helicopter’s ability to descend towards the surface to regain visual cues.
OUTCOME?
The pilot, the sole occupant, was fatally injured and the helicopter destroyed.
WHY?
The investigation concluded that the degraded visual environment caused by the flat light and whiteout led to inadvertent IMC, followed by spatial disorientation and loss of control.
It also identified several significant human-factors and training issues:
- In degraded visual environments flat light affects depth and motion cues before visibility becomes obviously poor. The pilot was inexperienced operating in snow and did not adequately recognise the developing threat.
- The pilot underestimated the severity of deteriorating conditions and his mental model displayed classic plan continuation bias with a commitment to returning to the airport, despite other opportunities to divert or land.
- Rather than transitioning to instruments, the pilot continued focusing on deteriorating external references. His last recorded instrument-flight practice was approximately nine years earlier.
- The helicopter had basic instruments suitable for IIMC recovery, but the pilots routinely operated with the artificial horizon switched off. Whether it was operating during the accident could not be established.
- Training and procedures concentrated on avoiding IMC, without providing adequate preparation for recognising and recovering from unexpected loss of visual references.
- The pilot retained the suspended sensor on the long line until he lost control. The investigation highlighted deficiencies in emergency decision-making training for external-load operations.
DVE is not just reduced visibility but involves the progressive loss of the visual information required to control the aircraft. Avoiding sliding into a DVE situation requires pilots to recognise the cues and deteriorating conditions early. It also requires the skills, instrument proficiency and recovery procedures to survive when avoidance fails.
REFERENCE?
Transportation Safety Board of Canada (2026). Collision with terrain, Bell 206L, Fort Chipewyan, Alberta, 12 February 2024. Air Transportation Safety Investigation Report A24W0016.
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.
