Misinterpretation of taxi instruction led to January 2016 runway incursion and risk of collision at Lester B. Pearson International Airport in Toronto, Ontario
Richmond Hill, Ontario, 24 May 2017 – In the release of its investigation report (A16O0016) today, the Transportation Safety Board of Canada (TSB) found that the misinterpretation of a taxi instruction issued by the ground controller led to the January 2016 Air Canada runway incursion and risk of collision at the Lester B. Pearson International Airport (CYYZ) in Toronto, Ontario.
On 30 January 2016, an Air Canada Embraer aircraft was operating as flight ACA726 on a scheduled flight from CYYZ in Toronto, Ontario, to LaGuardia Airport, New York, United States. While taxiing for departure, ACA726 taxied across the hold line and onto Runway 24R without authorization at the same time that an Air Canada Airbus, operating as flight ACA1259, was on final approach for landing on the same runway. As ACA726 was turning onto the runway centreline, the ACA1259 flight crew reported to the airport controller that there was an aircraft on the runway and that they were conducting an overshoot.
The investigation determined that, after completing their pre-departure preparations, the flight crew's expectation that they would quickly receive an authorization to take off, combined with the plain-language phraseology used by the ground controller, likely contributed to the crew's misunderstanding of the taxi instruction. Due to this misinterpretation, ACA726 taxied across the hold line and onto Runway 24R without authorization from the airport controller. This occurrence demonstrates how errors in communication can happen and why the use of standard phraseology that reinforces the clearance limit has the potential to improve safety. If air traffic controllers are not required to use standard phraseology that reinforces the need to hold short of a departure runway, there is an increased risk of miscommunication leading to runway incursions.
The investigation also found that the runway incursion monitoring and conflict alert system (RIMCAS) did not provide a timely warning to the airport controller to provide alternate instructions to the flight crews.
The risk of collisions on runways has been a key safety issue on the TSB Watchlist since 2010. The Board is concerned that unless better defenses are put in place to reduce these occurrences, the risk of a serious collision between aircraft remains.
Following this occurrence, Air Canada Flight Operations convened a working group to review this incident as well as other incursion incidents to identify any common causal factors and to develop recommendations to prevent future incursions. NAV CANADA performed a site review which resulted in adjustments that will increase the RIMCAS warning time to the air traffic controller when a departing aircraft enters the area without authorization.
See the investigation page for more information.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada
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