Incident Overview
On the morning of the occurrence, a runway incursion involved an Avitec Tractor 197 towing an Air Transat Airbus A310 aircraft and an Air Canada Boeing 767-200, operating as Flight 757, at Toronto/Lester B. Pearson International Airport. The tractor driver had received authorization to tow from Terminal 3 to the central de-icing facility via taxiways Sierra and Echo, crossing Runway 15L. At the same time, Flight 757 was cleared for take-off on Runway 15L. The tractor driver proceeded across the runway, prompting the flight crew to reject the take-off. No collision occurred.
Sequence of Events
At 0939:12, Tractor 197 requested clearance from the apron to the de-icing facility. The north ground controller issued authorization that implicitly included crossing Runway 15L. He did not coordinate with the north tower controller. At 0939:08, the north tower on-job trainee cleared Flight 757 to position on Runway 15L, and at 0940:40 cleared it for take-off. The OJT scanned the runway before issuing clearance but did not notice the approaching tractor. The on-job instructor also scanned and saw the tractor but assumed it would hold short. As Flight 757 began its take-off run, both controllers looked away to check the weather display. The clearance delivery controller saw the tractor entering the runway and shouted a warning. The north tower OJI instructed the flight crew to abort, but they had already initiated the rejection.
Tractor 197 had crossed the hold line and was on the runway when Flight 757 began its take-off. The driver saw Flight 757 on the runway but did not perceive motion until he was fully on the runway, at which point he continued crossing to vacate as quickly as possible. Flight 757 rejected take-off at a speed exceeding 90 knots, approximately 2500 feet down the runway, and slowed to below 40 knots by the time the tractor cleared, with the aircraft 1000 feet from taxiway Sierra.
Tower and ATC Operations
The tower was staffed by a supervisor, a tower controller in the South Tower, an OJT and OJI in the North Tower, two ground controllers (north and south), and a clearance delivery controller. The centre ground controller position was not staffed. Staffing was consistent with NAV CANADA policy, and controllers were properly qualified. The north ground controller had a heavy workload due to a recent runway change and re-sequencing of aircraft affected by departure restrictions. He did not coordinate the tractor movement with the north tower controller.
Tractor and Flight Crew Actions
The tractor driver was properly qualified under the GTAA airside vehicle operator program. He had been on duty since midnight but had slept and was well rested. After receiving authorization, he was under no obligation to obtain further clearance to cross the runway. He saw Flight 757 lined up but did not perceive motion or lights until after entering the runway. He continued to clear as expeditiously as possible.
Flight 757's flight crew turned on strobe and landing lights when cleared to position. During the initial take-off run, attention was partly inside the cockpit. The first officer noticed the tractor, initially expecting it to stop, then alerted the captain, and they rejected the take-off.
Context and Conditions
The runway change to 15L occurred about 10 minutes before the incident due to winds aloft. Visibility was 10-12 statute miles, ceiling 5300 feet, winds 120° at 8-9 knots. Prior to the change, a ramp hold had been imposed but lifted. The preferential runway system was consistent with policy. The airport's surface detection equipment (ASDE) was operating but was not used by the north ground controller and was not required. The runway incursion monitor/collision avoidance system was not on, as it was not yet commissioned due to false alarm issues.
Runway incursions are recognized as a worldwide problem. Transport Canada and NAV CANADA had undertaken studies, but these are not directly causative to this incident.