Pilot decision-making in poor weather contributed to fatal 2019 controlled flight into terrain accident near Mayo, Yukon
Edmonton, Alberta, 29 July 2020 — In its investigation report (A19W0105) released today, the Transportation Safety Board of Canada (TSB) found that pilot decision-making was a factor in a fatal controlled flight into terrain accident that occurred in 2019 near Mayo, Yukon.
On 6 August 2019, a Cessna 208B Grand Caravan operated by Alkan Air Ltd. was on a visual flight rules (VFR) flight from Rau Strip, Yukon to Mayo Airport, Yukon, with one pilot and one passenger on board. While enroute, the aircraft entered an area of low visibility and low cloud ceilings. The aircraft departed from the intended route, turned into a box canyon (having one-way access with steep walls) and struck rising terrain, fatally injuring the pilot and passenger. The aircraft was destroyed and there was a brief post-impact fire.
The investigation found that the pilot’s decision to continue a low altitude flight into poor weather conditions in mountainous terrain was influenced by several factors. The pilot had recently completed a flight along the same route, in similar weather conditions. The pilot’s decision-making would have been affected by his familiarity with the route and, consequently, he likely did not consider an alternate route to avoid the poor weather conditions.
The high speed at low altitude and low visibility reduced the opportunities for the pilot to take alternative action to avoid terrain. Within the box canyon, the canyon floor elevation increased abruptly within less than one nautical mile and the low visibility prevented the pilot from detecting this and taking sufficient actions to prevent a collision. Additionally, the aircraft’s terrain awareness and warning system aural alerts were ineffective in warning the pilot of the rising terrain because he had already heard multiple similar alerts in the preceding minutes of flight, or had silenced these alerts.
Following the occurrence, Alkan Air Ltd. made changes to its Caravan operations, including requiring a second flight crew member for Cessna 208B Grand Caravan captains with less than 2000 hours. Before becoming a captain on the Caravan, candidates must perform as a second crew member on the Caravan for 1 season. The company has also made modifications to its emergency response plan.
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
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