TSB Canada released the final report of their investigation into a serious runway incursion incident in which an unattended vehicle rolled across the active arrival runway at Toronto Airport. An Air Canada EMB-190 overflew the van at 35 feet (11 m) during landing.
On the evening of 11 March 2013, several Sunwing maintenance staff were assigned to complete scheduled maintenance tasks. An aircraft maintenance engineer (AME) and a technician were assigned to C-FTLK, a Boeing 737-800 parked at gate H16. The maintenance staff completed their tasks at approximately 2300,Footnote 1 although the contracted groomers were still onboard completing their duties. The technician drove the AME back to the company facility in a maintenance van, and returned alone to the aircraft to wait for the groomers to finish their tasks. The technician parked the vehicle abeam the nose of the aircraft on the left side in an area of broken pavement and remained in the vehicle with the engine running.
Approximately 30 minutes later, the groomers began to exit the aircraft from the left-hand main door. The last groomer off the aircraft attempted to close the door but was having difficulty due to the falling rain and the weight of the door. The technician observed this, drove the vehicle a few feet forward, exited the van, and instructed the groomer to stop, indicating his intention to take care of it. The technician then attended to the ground power unit (GPU), which was on the right side of the aircraft, before boarding the aircraft to check the cockpit. When the technician eventually exited the aircraft, he noticed that the vehicle was nowhere in sight.
While the technician was inside the aircraft, the unattended vehicle, at idle and in drive gear, had begun to roll. The vehicle grazed the outer cowling of C-FTLK’s left engine and continued under the wing in the direction of the threshold of runway 24R, the active arrival runway. As the vehicle proceeded across the apron and maneuvering area, the speed varied between 1 and 5 mph (1,6-8 km/h), likely due to the gradual slopes in the pavement. The ground controller noticed an unexpected slow-moving target on the airport surface detection equipment (ASDE) radar, and considered that it was possibly a false target.
When the vehicle was crossing runway 24R perpendicularly, almost directly over the displaced threshold, it was detected by controllers on the ASDE. As the runway 24R threshold is approximately 1.4 nautical miles (2,6 km) from the tower and in darkness the view is saturated with various lights from Terminal 1, visual identification was impossible.
The tower controller, realizing that there was an aircraft on final approach for runway 24R, radioed, “Air Canada 178 pull up and go around, sir”. This message came almost simultaneously with the “two hundred” EGPWS callout and went unnoticed by the flight crew.
Six seconds later, having heard no response from Air Canada 178, the tower controller again radioed, “Air Canada 178 pull up and go around”. The flight crew heard part of this transmission containing the words “go around”. The crew communicated between themselves and decided that the call could not have been for them.
The airplane flew directly overhead the van separated by approximately 35 feet (11 m), and landed on runway 24R. The controllers watched the aircraft land and watched the ASDE target disappear off the side of taxiway D7. The tower controller eventually established contact with Air Canada 178, now on the landing rollout, and asked if they had seen anything. The crew of Air Canada 178 replied that they had not.
The vehicle was located 14 minutes later, with the engine running, headlights, taillights, and beacon on, and the automatic transmission in drive.
The airplane involved in the incident was an Embraer EMB-190, C-FLWH, operating as flight Air Canada 178, inbound from Edmonton with 5 crew and 67 passengers on board. They were on an ILS approach.
Findings as to causes and contributing factors:
- The vehicle was left unattended in drive gear, resulting in the vehicle rolling across the active arrival runway.
- The air traffic controllers were unable to determine the identity of the target on the ground radar and as a result were uncertain as to its intended path.
- The airport surface detection equipment at the tower controller’s position was not being monitored. When the Stage 1 runway monitoring and incursion alert system (RIMCAS) visual alert was activated, it went unnoticed.
- The first air traffic control go around instruction was masked in the cockpit by a louder overlying enhanced ground proximity warning system automated callout, and the crew did not hear it.
- The second ATC go-around instruction issued by the tower controller was truncated by the transmitting and receiving radios. This, in combination with a rapid speech rate and elision, caused the aircraft call sign to be absent from the received transmission.
- Although the crew heard a “go-around” transmission, without other supporting cues such as visually sighting an obstacle, the crew did not interpret the instruction to apply to them. Consequently, the communication was insufficient to challenge the flight crew’s mental model of the situation, or their expectation of an uneventful landing.
- The RIMCAS Stage 2 aural alert was heard by the controllers 2 seconds before the conflict, which was too late to provide a useful warning.
- The vehicle beacon did not meet the standard required for airport operations, decreasing the likelihood that it would be seen by ground personnel, the flight crew or air traffic control.
- The flight crew did not see the vehicle and passed directly overhead, separated by approximately 35 feet, resulting in a risk of collision.