Canada’s Transportation Safety Board (TSB) released its report last week on the near collision between a Cessna Citation X and a Gulfstream V in NavCanada-controlled airspace on March 8 last year. Both aircraft, level at 43,000 feet and cleared on opposite-direction courses along J16, passed within one mile laterally and just under 1,000 feet vertically of each other near London, Ontario.

Standard separation required 2,000 feet vertically and five miles laterally.

Both crews took evasive action after receiving alerts from their traffic alert and collision avoidance systems.

On departure from Norman Y. Mineta San Jose International Airport (KSJC), the Citation was cleared by Oakland Center to climb eastbound to FL430, an altitude normally reserved for westbound traffic. The Gulfstream departed Laurence G. Hanscom Field (KBED) in Bedford, Mass., en route to San Francisco. The flight plans showed both aircraft using J16 between the Peck and London VORs. When the Cleveland Center sector controlling the eastbound Citation handed off the aircraft to the Toronto Center controller, no mention was made of the Citation’s unusual altitude for the direction of flight.

Additional links in the incident chain were a short loss of communication between the Cleveland controller and the Citation, as well as a controller shift change during the handoff at Toronto Center. During the position change at Toronto, the relieving controller was told both aircraft were at FL430 but was not told they represented a potential conflict. Ten seconds before the incident, the Toronto controller attempted to pass descent instructions to the Citation, but those instructions were never acknowledged.

Neither aircraft was damaged nor was anyone aboard either aircraft injured during the incident.