Report on Serious Incident at Svolvær Airport Helle, Norway on 2 December 2010, involving Bombardier DHC-8-103, LN-WIU operated by Widerøe's Flyveselskap AS
English translation is now available. During approach in darkness, LN-WIU suddenly had a significant loss of both speed and altitude. The flight crew regained control, but the airplane came very low (83 ft (25 m) above ground). During the recovery the airplane was exposed to high g-force and the engine torque limits were exceeded. The crew aborted the approach and continued to Leknes Airport where a normal landing was performed. The AIBN investigation indicates that the airplane at low altitude was exposed to significant wind shear (microburst), probably from a Cumulonimbus cloud (CB) in the area.
The Accident Investigation Board has, as part of this investigation, in particular focused on risk management and safety margins in connection with circling approaches in darkness. No obvious systemic failures or other deficiencies that could have influenced on the chain of events or causal factors was identified.
At one point during the chain of events, the First Officer took over the flight controls. The Commander did not oppose this. Apart from agreeing that this happened, the crew has given, in part, different descriptions of the chain of events. Based on the available facts, the Accident Investigation Board has not been able to determine neither which pilot did what, exactly when, and in which order, nor the effects of each action, seen in isolation. It has therefore not been possible to draw any solid conclusions about the significance of the actions of the first officer. The collective actions of the crew did, however, most likely lead to a recovery that was initiated in time to prevent the airplane from colliding with the ground.
The maneuvering to regain control was executed with sparse visual references and without a visible horizon. This investigation has revealed that the Commander was exposed to conditions that could provoke a somatogravic illusion. The Accident Investigation Board has, however, not found evidence to conclude that a spatial disorientation, if any, did have any effect on the Commanders handling of the wind shear.
This incident is an important reminder of the vulnerability connected to maneuvering low above the terrain with sparse visual references in darkness and turbulent air. It is also a reminder of the fact that operators and pilots with thorough knowledge of local conditions, experience and training beyond the regulatory minimum standards would be more capable of handling critical situations like this.
The incident happened in December 2010. This investigation was opened in Mid-February 2015. The circumstances concerning the date of the incident, reporting and classification are discussed in the report, which later will be translated into English.
No safety recommendation is issued in connection with this investigation.
The animation shows the chain of events.
|Location||Svolvaer Airport Helle (ENSH), Norway|
|ICAO Location indicator||ENSH|
|Type of occurrence||Serious incident|
|Type of operation||Scheduled air transport|
|Category of operation||Heavy, aeroplane (> 10 000kg)|
|Aircraft category||Landplane, Multi-engine, Turboprop/turboshaft|
|FIR/AOR||ENBD (Bodø ATCC)|