What happened
On an afternoon with clear skies and unlimited visibility, three aircraft operating under instrument flight rules experienced a loss of separation near Goose Bay, Newfoundland and Labrador. The incident involved an inbound Prince Edward Air Beech 1 900 (operating as Comet 9732) descending from flight level 210, and two outbound aircraft: an Air Labrador de Havilland DHC-8 (Labair 8301) cruising at 12,000 feet, and a Saab 340 (Speedair 7901) climbing through 13,000 feet.
The inbound CME9732 was descending toward 6,000 feet following a clearance from Goose Bay terminal control. The controller's strategy was to descend the inbound flight below the altitudes of the two outbound aircraft to maintain vertical separation. While the plan successfully separated the Saab 340 from the Beech 1900, the controller failed to maintain separation between the de Havilland DHC-8 and the inbound flight. Consequently, the two aircraft passed each other approximately 50 nm west of Goose Bay with only 1.8 nm of lateral spacing and 300 feet of vertical spacing, violating the required 3 nm lateral or 1,000 feet vertical separation standards. The crew of the LAL8301 was forced to deviate from their flight path following a collision-avoidance system (TCAS) resolution advisory.
The investigation
The investigation examined the air traffic control procedures and the technical capabilities of the radar equipment at Goose Bay. Investigators looked into the controller's management of the three-aircraft conflict and the specific separation plan implemented for the inbound and outbound traffic. The investigation also reviewed the lack of automated conflict alerts on the radar system used by the terminal control service.