The Departures North controller was controlling a Beechcraft Super Kingair B200C, radio callsign Alpha-Mike-Mike, and a British Aerospace BAe146 radio callsign Echo-Whiskey-Mike. Both aircraft had departed Sydney to the south-east. The crew of the Kingair were flying a radar departure, on a heading of 120 degrees, maintaining 5,000 ft. The crew of the BAe146 were flying a runway 16L COOKS ONE standard instrument departure (SID).
The Departures North controller confused the callsigns of the two aircraft and, although intending to turn the B200C, mistakenly instructed the crew of the BAe146 to turn left onto a heading of 350 degrees. The BAe146 was then cleared to leave 5,000 ft on climb to flight level 240. The combination of both instructions placed the BAe146 in the Approach South/Director controller's airspace and in potential conflict with a Boeing B737 on left downwind for runway 25 that had been assigned descent to 5,000 ft.
Both the Approach South controller and the Departures North controller recognised that the aircraft were in conflict as soon as the BAe146 started to turn onto the assigned heading and issued remedial instructions to both crews.
The required separation standard was either 1,000 ft vertically or 3 NM horizontally. Analysis of the radar data indicates that the B737 did not descend below 5,500 ft and that the BAe146 did not climb above 4,600 ft. The vertical difference of 900 ft occurred while the aircraft were less than 3NM apart and there was consequently an infringement of the separation standards.
The crew of the BAe146 sighted the B737 and were able to maintain visual separation.
The investigation revealed that the Departures North controller had worked six extra shifts on overtime or emergency duty in the previous 7 weeks, including an overtime shift the previous day. Fatigue was considered to be a contributory factor.
LOCAL SAFETY ACTION
Air Traffic Control Management at Sydney made two recommendations as a result of this incident:
"Recommendation 1. That strategies be put in place to limit the amount of overtime or extra duties worked by terminal control unit (TCU) staff. Should the present measures be withdrawn, other measures will be necessary".
"Recommendation 2. That the mode of operation, 16 Departures/25 Arrivals, be reviewed so as to permit two outbound radials to the north for different performance aircraft".
BASI SAFETY ACTION
As a result of this investigation and a number of similar occurrences, the Bureau of Air Safety Investigation conducted an investigation of systemic issues at the Sydney terminal control unit and issued report B98/90 on 18 August 1998. Nine recommendations were made in the report. The following two recommendations are considered relevant to this investigation.
R980159
The Bureau of Air Safety Investigation recommends that Airservices Australia reassess the human factor hazard analysis for both Stage One and Stage Two of the long-term operating plan (LTOP) safety cases so that the mitigating strategies applied to identified hazards adequately allow for the fundamental limitations of human performance. In reassessing this hazard analysis, BASI recommends that Airservices Australia seek the assistance of human performance expertise.
R980160
The Bureau of Air Safety Investigation recommends that Airservices Australia consider restructuring the current roster operating in the Sydney TCU to ensure that contemporary fatigue management research is translated into meaningful duty hour regulations. In any restructure of the roster, BASI recommends that Airservices Australia expand its absentee management program to include individuals who expose themselves to the risks of fatigue by participating in excessive amounts of overtime and/or emergency duty.