Limited visual cues and runway conditions contributed to runway excursion of passenger aircraft in Terrace, BC
Richmond, British Columbia, 22 July 2021 — In its investigation report (A20P0013) released today, the Transportation Safety Board of Canada (TSB) found that limited visual cues due to falling snow and a snow-covered runway contributed to the 2020 runway excursion involving a WestJet Encore De Havilland of Canada Ltd. DHC-8-402 in Terrace, British Columbia.
On 31 January 2020, a De Havilland Aircraft of Canada Ltd. DHC-8-402 aircraft was conducting WestJet Encore flight WEN3107 from Vancouver, BC to Terrace, BC with four crew members and 43 passengers on board. During the landing roll, the aircraft drifted left from the snow-cleared area of the runway and the left main landing gear exited the runway surface, travelling for approximately 400 feet before returning to the runway. During the runway excursion, the aircraft’s nose landing gear collapsed. The aircraft came to a stop in the centre of the runway. The passengers were transported to the airport terminal by bus approximately 30 minutes after landing. No injuries were reported. The damage to the aircraft included the collapsed nose landing gear and damaged right propeller blades.
The investigation found that, given the falling snow and the snow-covered runway, there were limited visual cues available to the flight crew, which decreased their ability to accurately judge the aircraft’s lateral position once it was beyond the runway threshold. Snow clearing operations cleared the centre 100 feet of the runway, which resulted in windrows that were approximately 18 inches high along the edges of the cleared area. This reduced the pilot’s lateral maneuvering room during the landing.
It was also determined that the aircraft initially touched down 10 feet left of the centreline due to control inputs and variable wind conditions and, while the aircraft was still in a light weight-on-wheels condition, a gust contributed to a further deviation to the left until the left main landing gear came into contact with the windrow. As a result, the aircraft was pulled to the left and travelled through the uncleared portion of the runway. During the runway excursion, snow and ice became packed in the nose landing gear bay and caused structural deformation. Consequently, the nose landing gear was no longer being held in place and collapsed rearward into the fuselage, causing substantial damage to the aircraft.
Finally, the investigation also determined that, if aircraft operators do not provide pilots with all the possible tools and relevant information to assess runway suitability for landing, pilots may not evaluate all potential threats and may make decisions based on incomplete or conflicting information.
Following the occurrence, WestJet Encore issued a revision to the Quick Reference Handbook on 14 February 2020 that included changes to contaminated runway operations. The Terrace-Kitimat Airport Society issued a memo informing staff of changes to its Winter Maintenance Plan, which aligned the procedures with Issue 04 of Transport Canada’s Advisory Circular 302-013: Airport Winter Maintenance and Planning.
See the investigation page for more information.
The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada