What happened
On 3 January 2019, two aircraft flying under instrument flight rules experienced a loss of separation west of Kelowna, British Columbia. The first aircraft, a WestJet Encore Bombardier DHC-8-402 (registration C-FSWE), was traveling southwest from Calgary International Airport toward Nanaimo Airport. Simultaneously, a Piaggio P.180 (registration N990RS), operated by Rainbow Sandals Retail Incorporated, was flying north-northwest from Spokane International Airport to Kamloops Airport.
Both aircraft were cruising at flight level 220. As the aircraft approached a crossing point west of Kelowna, they failed to maintain the required vertical separation of 1,000 feet or the lateral separation of 5 nautical miles. At 1021:11 Pacific Standard Time, the aircraft were at the same altitude and were positioned less than 5 nautical miles apart on converging flight paths.
The investigation
The investigation examined the flight paths and the automated systems active during the encounter. At 1021:20, the crew of the C-FSWE received a traffic alert and a collision avoidance system resolution advisory instructing them to descend. During this same period, the crew of the N990RS received a traffic advisory. By 1021:49, the vertical separation had been restored to 1,000 feet, though the lateral distance between the two aircraft had decreased to 0.9 nautical miles. No injuries or damage were reported, and both flights reached their destinations safely.
Findings
- The loss of separation was driven by error in flight plan data.
- The aircraft were operating on converging tracks at the same altitude.
- The collision avoidance system functioned as intended by providing resolution advisories to the flight crews.