On 23 October 2001, at Toronto Pearson Airport, a B767 Series cleared for take-off was forced to reject the take-off when a tractor towing an AIRBUS A-310 crossed the runway ahead of it. The tractor had been cleared to cross the active runway by ATC.
The following is the summary from the official TSB (Canada) report:
"Avitec Tractor 197 was towing an Air Transat Airbus A310 aircraft from Terminal 3 on the east side of Toronto/Lester B. Pearson International Airport to the central de-icing facility on the west side of Runway 15L. The tractor driver had received and acknowledged authorization to tow via taxiway Sierra (which crosses Runway 15L) and taxiway Echo, to hold short of taxiway Tango. At the same time, Air Canada Flight 757, a Boeing 767-200 aircraft, was cleared to position on Runway 15L. A minute and a half later, Flight 757 was cleared for take-off. At that moment Tractor 197 was crossing the hold line on taxiway Sierra, proceeding to cross Runway 15L in accordance with his authorization. The tractor driver saw Flight 757 in position on the runway but did not perceive it to be in motion until he was fully onto the runway and in a position where he had no alternative but to continue to cross in order to vacate the runway as quickly as possible. After commencing their take-off, the flight crew of Flight 757 observed the tractor and tow entering the runway. They rejected the take-off, reaching a speed in excess of 90 kts approximately 2500 feet down the runway, 3500 feet from taxiway Sierra. When Tractor 197 cleared the runway, the aircraft had slowed to less than 40 kts and was 1000 feet from taxiway Sierra. Flight 757 cleared the runway at taxiway Sierra."
The report made the following conclusions regarding cause and contributing factors:
"...The north ground controller inadvertently cleared Tractor 197, with an Airbus A310 aircraft in tow, across the active runway at the same time as Flight 757 was cleared for take-off by the north tower (on-job trainee) controller. The north ground controller clearance to Tractor 197 did not contain an explicit instruction to 'cross' the runway as required by the Air Traffic Control Manual of Operations (ATC MANOPS), nor did the north ground controller co-ordinate the movement of Tractor 197 with the north tower controller.
Task saturation of the north ground controller, as a result of weather delays and a runway change, likely contributed to his momentary lapse of attention.
Airside vehicle operators are not required to stop and hold short of runways, as are pilots, if they do not have an explicit clearance from ATC to cross that specific runway. As a result, vehicle operators do not serve, as do pilots, as an independent defence against air traffic control error."