The Boeing 747 (B747) was on descent for an arrival at Sydney. The crew was being radar vectored to runway 16R for sequencing behind a SAAB 340 that was being radar vectored to runway 16L. Procedures at Sydney had different air traffic controllers responsible for directing the traffic to each of the parallel runways. The Director West controller positioned aircraft on final for runway 16R and the Director East for runway 16L.
The Director West controller was sequencing the B747 and assigned a heading of 060 degrees magnetic with an instruction to report when the crew had the field in sight.
The crew of the B747 reported the field in sight and the Director West controller told the crew to expect to go right up to the localiser, with a right turn to intercept from the eastern side. The crew acknowledged with a partly unintelligible transmission that included the words "roger" (unintelligible) "localiser into".
Almost immediately, the crew of the B747 turned their aircraft away from the assigned heading onto a heading of 110 degrees to intercept the runway 16R localiser. They advised air traffic control that they were now right heading 110. This particular heading placed the aircraft in potential conflict with the SAAB. The Director West controller instructed the crew of the B747 to maintain a heading of 060 degrees to ensure that the aircraft passed behind the SAAB. The Director East controller passed traffic information regarding the B747 to the crew of the SAAB.
Although the crew of the SAAB reported that they had the B747 sighted, radar separation between the two aircraft was reduced to 2.5 NM during the manoeuvre. The separation standard required was either 3 NM horizontally or 1,000 ft vertically. Analysis of the radar data indicated that vertical separation between the two aircraft was reduced to approximately 800 ft when the 3-NM radar separation standard was infringed.