What happened
On an afternoon in Alberta, two aircraft flying under instrument flight rules nearly collided approximately 60 nautical miles southeast of Edmonton International Airport. The first aircraft, a BA3112 registered as C-GKGM and operated by Corpac Canada Ltd., was traveling from Fort McMurray to Calgary. The second aircraft, a SA227DC registered as C-FDMR and operated by Alta Flights (Charters Inc.), was flying from Calgary to Edmonton City Centre Airport.
Due to severe thunderstorms and restricted airspace surrounding the G-8 Conference at Kananakis, both flights were diverted east of their planned routes. At 16:10 mountain daylight time, the two aircraft met on nearly reciprocal headings at 16,000 feet. The aircraft were separated by only 200 feet vertically and 1.3 nautical miles laterally, failing to meet the required separation of 1,000 feet vertical and 5 nautical miles lateral. The aircraft passed through clouds, and neither crew observed the other.
The investigation
The investigation focused on the operations within the Edmonton Area Control Centre (ACC), specifically the Red Deer sector. Investigators found that C-GKGM was operating at an altitude that was inappropriate for its direction of flight. While the aircraft was initially at a valid altitude, its track change necessitated a different flight level, which was not corrected.
Controllers in the Red Deer sector were managing a high-complexity environment characterized by a surge in traffic following the lifting of a Calgary terminal air stop. The workload was further intensified by the need to navigate around thunderstorm cells and the restricted Class F airspace for the G-8 Conference. The investigation also examined the lack of a ground-based conflict alert system and the absence of Traffic Alert and Collision Avoidance Systems (TCAS) on both aircraft.
Findings
- C-GKGM was permitted to fly at an altitude that did not comply with standard regulations for its direction of travel, which reduced the safety margin between opposing traffic.
- Flight progress strips were not marked with the necessary warnings to alert controllers to the altitude discrepancy.
- The radar controller failed to adequately scan the display for other traffic before clearing C-FDMR to the same altitude occupied by C-GKM.
- High traffic density, caused by weather diversions and G-8 airspace restrictions, created a high-workload environment that degraded the situational awareness of the controllers.
- The supervisor was occupied in a control position rather than performing supervisory duties, which prevented effective personnel management during the traffic surge.
- The primary cause was the failure to maintain appropriate altitude separation due to the aircraft operating at an altitude inappropriate for its direction of flight.