A near miss in the sky over Kelowna last year resulted in a TSB investigation.
Last year, two planes nearly missed the skies over Kelowna, according to the Transportation Safety Board of Canada.
The TSB released the results of its investigation into a “loss of separation” between a WestJet Encore Bombardier Q400 and a private Piaggio P.180 twin-turboprop aircraft on January 3, 2019.
The probe found an error in the flight plan data and an increased workload for the air traffic controller was to blame for the incident. A loss of separation is defined as two aircraft in the required vertical separation minimum of 1000 feet or lateral separation minimum of 5 nautical miles.
The WestJet Encore flight left Calgary for Nanaimo at the same time as the Piaggio was traveling from Spokane to Kamloops. The two flights provided air traffic control services through central Vancouver and flew approximately 22,000 feet above sea level.
TSB claims that the flight data processor at the Vancouver Area Control Center had undergone a software update before the occurrence, but that some previous data had not been purged, resulting in a disparity between the data of the flight plan and the flight path identified by Piaggio radar. .
“The controller was not familiar with such disparity errors and in his attempts to resolve the deviation for the Piaggio, did not identify the potential conflict between the Westjet Encore and Piaggio flight plans,” said the TSB. .
The error meant that the software designed to predict traffic conflicts, on which the controller had come to rely, was not working properly.
“The volume of traffic in the airspace had increased, causing a heavy workload for the controller. The controller did not see or hear the visual and audible warnings when the two aircraft approached each other, “said the TSB.
The collision was avoided when a system on board WestJet Encore told the crew to decrease the altitude. The Piaggio pilot maintained altitude and saw the Westjet Encore aircraft descend.
The flights were as close as 1000 feet vertically and 0.9 nautical miles laterally.
“The investigation also identified risks to the controllers ‘familiarity with equipment errors and the adequacy of the supervisors’ workload monitoring by the team supervisors,” concluded the TSB.
NAV CANADA made several security changes after the incident, including improvements to software update procedures and a new directive for controllers regarding setting the minimum volume for audible alerts.
The full survey can be found here.