Canada A320 at Calgary on Dec 2nd 2016, continued takeoff despite aircraft crossing runway

Last Update: February 5, 2018 / 18:13:03 GMT/Zulu time

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Incident Facts

Date of incident
Dec 2, 2016

Classification
Incident

Airline
Air Canada

Flight number
AC-221

Departure
Calgary, Canada

Destination
Vancouver, Canada

Aircraft Registration
C-FDQV

Aircraft Type
Airbus A320

ICAO Type Designator
A320

An Air Canada Airbus A320-200, registration C-FDQV performing flight AC-221 from Calgary,AB to Vancouver,BC (Canada), had been cleared for takeoff from runway 29 and was accelerating through 100 KIAS when the crew spotted a Swearingen SA-226 crossing the runway. As the SA-226 was already more than half across the runway, the A320 crew continued takeoff and continued to destination without further incident.

The Canadian TSB reported the SA-226 had been cleared to cross the runway when the A320 was about 2200 feet into the takeoff roll. The Canadian TSB opened an investigation into the occurrence rated "risk of collision".

On Feb 5th 2018 the TSB released their final report concluding the probable cause of the serious incident was:

Findings as to causes and contributing factors

- The runway incursion occurred after the combined ground controller cleared C-FGEW to cross Runway 29 while Air Canada flight 221 was departing on Runway 29.

- Due to a strong habit intrusion error, the combined ground controller reverted to the frequently practised routine of instructing the aircraft to cross Runway 29 without prior coordination with the combined tower controller.

- The infrequent use of Runway 29 during the day, together with the absence of relevant training scenarios or simulation of Runway 29 operations, meant that controllers rarely encountered situations where the need to coordinate prior to executing crossings of Runway 29 was reinforced.

- The runway jurisdiction system did not provide a sufficiently compelling cue to ensure that the combined ground controller did not revert to the well-practised routine of clearing aircraft across Runway 29 without coordination.

Findings as to risk

- If proposed safety actions are not tracked to completion, there is an increased likelihood that identified safety risks will not be effectively mitigated.

The TSB analysed:

The combined ground controller was aware that the tower controller had jurisdiction of Runway 29, and that arrivals and departures were taking place on that runway. In the 15 minutes preceding the occurrence, the combined ground controller had received a transfer-of-position-responsibility briefing, prompted by the change in runway configuration. The combined ground controller had issued taxi instructions for ACA221 to proceed to Runway 29, and had provided taxi instructions to 2 other aircraft that had already landed on Runway 29.

The combined ground controller intended to coordinate with the combined tower controller prior to clearing C-FGEW to cross Runway 29. However, at the time when C-FGEW was approaching Runway 29, the combined ground controller automatically instructed the aircraft to cross without coordinating with the combined tower controller.

Since the introduction of the parallel runway operation, Runway 29 has been used infrequently for daytime operations. It is usually under the jurisdiction of ground controllers, and aircraft frequently cross it. As a result, controllers have developed a strong schema for automatically clearing aircraft across without coordination. Further, in the moments before clearing C-FGEW to cross Runway 29, the combined ground controller’s attention had been devoted to ensuring that there would be no conflict between C-FGEW and the CRJ900 at the intersection of taxiways A and J.

All of the criteria for a strong habit intrusion error were present. The controller was carrying out a well-practised task in familiar surroundings, he intended to depart from routine, and to do so, he had to overcome a strong schema for the usual pattern of actions.29 In addition, the controller’s attention was devoted to another aspect of the task at the moment when an attentional check should have been expected. Due to a strong habit intrusion error, the combined ground controller reverted to the frequently practised routine of instructing the aircraft to cross Runway 29 without prior coordination with the combined tower controller.
While this type of error is common, it is also predictable and can be prevented. Potential mitigations include memory aids that ensure that attentional checks are conducted at the appropriate time, and training that reinforces the alternate schema through practice.