Bounced landing, improper recovery contributed to crash
Jan. 9, 2013, Gatineau, Que. - The Transportation Safety Board of Canada (TSB) today released its investigation report (A11W0144) into the collision with a building of a de Havilland DHC-6-300 Twin Otter float plane September 22, 2011 in Yellowknife, Northwest Territories.
The Twin Otter was flying from a mining camp at Thor Lake, Northwest Territories, to the Yellowknife float-plane base with seven passengers and two pilots aboard. While attempting to land during gusty and variable wind conditions, the aircraft bounced, then porpoised and landed hard on the right float. The flight crew aborted the landing, and the aircraft lifted off in a nose-high, right-wing-low attitude that continued with a right turn towards the shore. The aircraft then struck power lines and the side of a building before coming to rest in an adjacent parking lot. The two pilots were fatally injured, four passengers were seriously injured, and three passengers sustained minor injuries. The aircraft was substantially damaged but there was no fire.
The investigation found that changes in airspeed and the gusty wind conditions led to a bounced landing. The crew attempted a recovery, initiating a go-around by raising the nose of the aircraft and applying full power with the wing flaps fully extended. However, the Twin Otter's aircraft flight manual cautions against raising the nose beyond level flight attitude during a go-around with fully extended flaps, as raising the nose too high might cause a rapid decrease in airspeed and a possible aerodynamic stall. The aircraft lifted off the water with its nose very high and the right wing low. In this configuration, the aircraft could not accelerate or climb, and it collided with power lines and a building.