What happened
On the evening of December 2, 2010, a Bombardier DHC-8-103, registration LN-WIU, was performing a flight from Bodø to Svolvær Airport Helle. The aircraft, operated by Widerøe, was carrying three crew members and 3/5 passengers. The conditions at the destination were challenging, characterized by darkness, rain, hail, and gale-force winds with significant gusts.
As the pilot flying attempted a visual circling maneuver over the sea to prepare for a landing towards the south, the aircraft encountered severe wind shear originating from a cumulonimbus cloud. This sudden atmospheric disturbance caused the plane to buffet violently, lose airspeed, and drop in altitude. The stall warning activated as the aircraft's performance degraded rapidly.
During this intense 10-second sequence, the aircraft's altitude plummeted to just 25 meters above the water. While there were conflicting accounts between the crew regarding who took primary control, their combined actions—including increasing engine power to maximum—allowed the aircraft to recover and climb. The crew subsequently aborted the approach and diverted to Leknes, where they landed safely without any injuries or damage to the aircraft.
The investigation
The Norwegian Safety Investigation Board (NSIA) examined flight recorder data and crew statements to reconstruct the event. The investigation focused on the meteorological conditions at Svolvær, which included high winds and convective activity. Investigators also looked into the possibility of sensory illusions, such as a somatogravic illusion, given that the maneuver was performed in darkness with very few visual references.
Findings
- The primary cause of the altitude loss was severe wind shear from a cumulonimbus cloud.
- The crew was operating in high-risk conditions involving low-altitude maneuvering in darkness and turbulent air.
- The pilot flying may have been susceptible to sensory illusions due to the lack of a visible horizon and sparse visual references during the circling maneuver.
- The fatigue of the commander, who had started his duty early, was noted as a factor in the operational context.