What happened
At 1608 EDT, a Royal Dutch Airlines Boeing 747-400, registration PH-BFY, was cleared to land on Runway 05 at Toronto/Lester B. Pearson International Airport. Simultaneously, a Thomas Cook Airlines Boeing 757-200, registration G-FCLI, was cleared for takeoff from Runway 33R. This clearance created a direct conflict, as the two aircraft paths were set to intersect.
Shortly before the incident, air traffic controllers coordinated a shift in runway operations to accommodate changing weather conditions. The plan was to transition arrivals from Runway 06L to Runway 05 and departures from Runway 3HD to Runway 06L. During this transition, the Boeing 757-200 began its takeoff roll, reaching a ground speed of 126 knots. At that moment, the Boeing 747-400 was only 1.0 nm from the Runway 05 threshold.
Upon noticing the conflict, the airport controller and tower supervisor ordered the Boeing 757-200 to abort its takeoff. The crew of G-FCLI performed a high-speed rejected takeoff, coming to a stop on Runway 33R. The PH-BFY aircraft passed the intersection safely without realizing a conflict had occurred.
The investigation
The investigation examined the coordination processes between the Toronto area control centre and the tower during runway changes. It was established that the required coordination to identify the last aircraft on the old runway and the first on the new runway was not completed according to published procedures.
Investigators also looked into the capabilities of the airport's surface detection equipment. The existing system was found to be unable to provide alerts for potential collisions involving aircraft on crossing runways. Furthermore, the investigation reviewed the workload of the controller, noting that the transition period involved managing multiple tasks, including equipment setup and receiving new departure restrictions.
Findings
- The primary cause of the loss of separation was task saturation of the airport controller, which led to a failure to detect the conflict between the arriving and departing aircraft.
- Incomplete inter-unit coordination meant the incoming Boeing 747-400 was transferred to tower control without the necessary pre-coordination regarding the runway change.
- A lack of standard operating procedures for the tower supervisor contributed to the error, as the supervisor was engaged in lower-priority tasks during the transition.
- The airport's runway incursion monitoring system was incapable of detecting and alerting the controller to the high-speed risk on crossing runways.