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The Transportation Safety Board of Canada (TSB) released its investigation report (A17O0025) into the runway excursion of Air Canada flight 623 at Toronto/Lester B. Pearson International Airport, in Ontario.
The investigation determined that weather conditions and lack of runway centreline lighting reduced the cues available to recognize the aircraft’s drift in time to correct the trajectory or to execute a safe go-around.
On Feb. 25, 2017, the Airbus A320 was completing an evening flight to Toronto from Halifax/Stanfield International Airport, N.S., with six crew members and 119 passengers on board.
Just before touchdown, the aircraft began to deviate to the right of the runway centreline. It deviated further to the right after touchdown and entered the grassy area to the west of the runway.
It then travelled approximately 2,390 feet through the grass parallel to the runway before returning to the pavement.
During the excursion, the aircraft struck five runway edge lights, causing minor damage to the left outboard wheel and the left engine cowling. There were no reported injuries.
The investigation found that during the final approach phase, while the aircraft was less than 30 feet above ground and on the runway centreline, a right roll command input caused the aircraft to enter a shallow right bank and start drifting to the right.
The crew had limited visual cues to accurately judge the aircraft’s lateral position because of rain, reduced windshield wiper capability and lack of runway centreline lighting.
The severity of the drift was not recognized until the aircraft was less than 10 feet above ground and rapidly approaching the runway edge, which left limited time to correct the aircraft’s trajectory before contacting the surface.
Given the risks involved in executing a go-around from a low level in response to significant drift, the pilot continued the landing sequence while attempting to minimize the extent of the excursion.
Following the accident, Air Canada instituted a program for inspections of windshield wiper tension, developed a drift training scenario for the simulator, and issued further flight crew guidance on lateral drifts and lateral runway excursions.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation 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.
