Photo: TSB

A near miss in the skies above Kelowna last year resulted in an investigation by the TSB.

Two airplanes had a near miss in the skies above Kelowna last year, 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 private Piaggio P.180 twin turboprop aircraft on Jan. 3, 2019.

The probe found an error in flight plan data and increased workload for the air traffic controller was to blame for the incident. A loss of separation is defined as two planes being within the required vertical separation minimum of 1000 feet or lateral separation minimum of 5 nautical miles.

The WestJet Encore flight had left Calgary for Nanaimo at the same time the Piaggio was travelling from Spokane to Kamloops. Both flights were being provided air traffic control services by the Vancouver centre and were flying at about 22,000 feet above sea level.

The TSB says the flight data processor at the Vancouver Area Control Centre had undergone a software update prior to the incident, but some previous data had not been purged, leading to a disparity between the flight plan data and the radar identified flight path of the Piaggio.

“The controller was not familiar with such disparity errors and in his attempts to resolve the discrepancy for the Piaggio, did not identify the potential conflict between the Westjet Encore and Piaggio flight plans,” the TSB said.

The error meant the software designed to predict traffic conflicts, that the controller had come to rely on, was not operating properly. 

“Traffic volume in the airspace had increased, leading to a high workload for the controller. The controller did not see or hear the visual and audible warnings as the two aircraft approached one another,” the TSB said.

The collision was avoided when a system on board the WestJet Encore flight told the crew to decrease altitude. The pilot of the Piaggio maintained altitude and saw the Westjet Encore aircraft descending.

The flights came as close as 1000 feet vertically and 0.9 nautical miles laterally. 

“The investigation also identified risks regarding controller familiarity with equipment errors, and the adequacy of controller workload monitoring by team supervisors,” the TSB concluded.

After the incident, NAV CANADA made several safety changes, including making improvements to software update procedures and a new directive for controllers regarding the minimum volume setting for audible alerts. 

The full investigation can be found here.