Incident at In the vicinity of: CORAL HARBOUR NU (CYZS) (Conflict - loss of separation, ATS operating irregularity)
2001-06-11: The crew of SAS 938, a B767-300 enroute from Seattle to Kastrup, reported by 64/80 through Arctic Radio, but the flight planned route indicated that 63/80 was supposed to be the flight's position. When questioned, the pilot advised they had been re-routed by the previous ACC. The new position took the flight one degree north of traffic SAS 938 was longitudinally ahead of by 13 minutes on estimates. By taking this aircraft off its flight planned route, the separation between it and KLM 602, a B747 enroute Los Angeles to Amsterdam, was now put into jeopardy. On the same route, standard procedure is to run aircraft 10 minutes longitudinally separated at the same altitude and same Mach number. If the routes are same direction, but not identical, standard procedure is to have 15 minutes longitudinal. In this case, the two a/c were flying identical flight plans to start, but then one aircraft was re-routed, which made them same direction only. The estimates passed were 13 minutes apart but the position reports at 80 west made the aircraft only 9 minutes apart and they joined up again at 65/70, which meant there was not enough spacing between them. As a result the Controller moved SAS 938 down to FL 310 (both aircraft had been at FL 330).
2001-06-13: UPDATE ANS and Airspace advised that TSB will investigate this occurrence.
2001-06-15: UPDATE TSB reported that the Scandinavian Airlines flight SAS 938, a Boeing 767-300, registration LN-RCH, was re-routed by Winnipeg ACC via position N64W80 at FL 330. This resulted in a loss of separation with Royal Dutch Airlines flight KLM 602, a Boeing 747-300, registration PH-BUR, which had been following SAS 938 at FL 330 with the required same route separation of ten minutes. With the route change, the required separation became 15 minutes. Additionally, the clearance created a track re-interception at position N65W70. At this position, separation was not assured. When SAS 938 made a position report at N64W80 to Edmonton ACC, the operating irregularity was identified and SAS 938 was moved to FL 310.
|Occurred At||- 05:43|
|Day or Night?|
|TSB Occurrence Number|
|TSB Class of Investigation|