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Misinterpretation of ATC communication factor in August 2019 runway incursion at Toronto
15 January 2021

The Transportation Safety Board of Canada (TSB) released its investigation report into the August 2019 runway incursion between two aircraft at the Toronto/Lester B. Pearson International Airport, Canada.

On 9 August 2019 at 12:40 local time, an Air Canada Boeing 777-300 landed on runway 33L. Three minutes later, an Air Georgian CRJ-200 was instructed to line up on parallel runway 33R. In accordance with air traffic control (ATC) instructions, the Boeing 777 was crossing runway 33R. Simultaneously, the flight crew of the CRJ-200 began its take-off roll on the same runway without a take-off clearance from ATC. When the CRJ-200 flight crew saw the Boeing 777 over the crest of the runway, they rejected the takeoff and exited via a taxiway.

The investigation found that while completing the pre-departure checks, the flight crew of the CRJ-

200 was informed of a change in departure instructions. The first officer received and read back the line-up instruction with the departure amendment, but misinterpreted that ATC communication as a clearance for takeoff.

It was determined that the number of pre-departure tasks the flight crew was required to complete within a short amount of time increased their workload, and that the workload was further increased by the additional tasks brought by the change in instructions. Thus, it was found that the increased workload, the expectation to receive a take-off clearance without delay, and the misinterpretation of the line-up instructions led the CRJ-200 flight crew to initiate take-off roll without a take-off clearance. Also, because of the grade profile of runway 33R, the fuselage of the Boeing 777 would not have been visible to the CRJ-200 flight crew at the start of the take-off roll, therefore they had no visual indication that it was unsafe to begin the takeoff.

Following the occurrence, NAV CANADA issued a directive reminding air traffic controllers to cancel the take-off clearance or issue an instruction to abort takeoff when runway incursion monitoring and conflict alert system stage 2 alerts are activated by a departing aircraft.

Air Georgian Limited conducted an internal safety investigation as per the company’s safety management system. It amended its standard operating procedures to mandate an ATC query if one of the two crew members was unaware of the content of an ATC clearance or instruction.

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