Poor visibility and vehicle tracking data error contributed to 2019 runway incursion

From: Transportation Safety Board of Canada

On 28 January 2019, a Sky Regional Airlines Embraer ERJ 170-200 was preparing to depart on Runway 06L for a flight from Toronto/Lester B. Pearson International Airport (CYYZ), Ontario, to Dallas-Fort Worth International Airport (DFW), Texas, United States. At the same time, a group of four snow removal vehicles was operating north of this runway and had been instructed by ground control to turn left onto Taxiway C to continue their operations. However, heavy snow had obscured visual cues on the taxiways and the vehicles inadvertently lined up with the entrance to Taxiway C2 instead. They kept moving toward Runway 06L, when three of the vehicles continued past the runway holding position. The ground controller then instructed the vehicles to stop, which they did just before reaching the runway surface. The tower controller instructed the flight crew of the departing aircraft to abort the takeoff. After rejecting the takeoff, the aircraft came to a stop on the runway just short of the intersection with Taxiway C2, with the plows approximately 200 feet to the left of the aircraft. None of the vehicles nor the aircraft were damaged and no injuries were reported.

The investigation found that, in December 2018, a transponder from one of the snow removal vehicles (PLOW 170) was installed onto another (PLOW 862) without the transponder code being updated. As a result, the vehicle was incorrectly identified on the ground radar system. It was also found that, at the time of the occurrence, the NAV CANADA control tower at CYYZ did not have procedures to follow if there was a mismatch between a vehicle call sign and its transponder code.

Additionally, the investigation determined that because of reduced visibility from blowing snow, the operator of the lead vehicle, PLOW 862, was not aware that the vehicle was on Taxiway C2, as it approached the holding position. As a result, the operator was not looking for, nor expecting to see, any of the visual cues that would have alerted him that the vehicle was approaching an active runway. Further, some of the visual cues at the runway holding position were obscured by snow, while others may not have been working. The cues were not conspicuous enough to alert the operator of PLOW 862 to the vehicle’s proximity to the runway. This led to the first three vehicles proceeding past the holding position towards the runway.

The ground controller recognized the incursion by PLOW 862 and instructed the vehicle to stop four times; however, the first two instructions were addressed to PLOW 170 rather than PLOW 862, because of the transponder mismatch. Immediately after the ground controller used the correct call sign, PLOW 862 came to a stop after crossing the holding position on Taxiway C2.

The risk of collisions from runway incursions has been on the TSB Watchlist since its inception in 2010 and calls for effective defences tailored to address identified hazards at airports and in aircraft, vehicles, and air traffic service facilities across Canada.

Following this occurrence, the Greater Toronto Airports Authority (GTAA) amended its standard operating procedure to ensure that the correct code is displayed by NAV CANADA’s systems when a new transponder is installed on an airport vehicle. Also, in response to TSB Recommendation A18-04, NAV CANADA has amended its abort takeoff phraseology to include repetition as a method to ensure that the instructions are sufficiently compelling to be recognized during periods of high workload, such as takeoff.

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