Aviation safety investigations & reports

Boeing Co 737-376, VH-TAI

Investigation number:
Status: Completed
Investigation completed


Sydney airport and associated airspace was being operated in accordance with Mode 9 of the Long Term Operating Plan. A Boeing 737 (B737) departed runway 34R for Melbourne and was cleared initially to 5,000 ft on a MARUB ONE standard instrument departure (SID), with a Wollongong transition. The SID required the crew to intercept and track via the 075 Sydney VOR radial to 15 NM (waypoint MARUB), and to then turn right and track 144 degrees until passing 9,000 ft.

At the same time, another B737 inbound to Sydney on a CHEZA THREE standard arrival route (STAR) for a landing on runway 34R had passed waypoint WHALE, located 20 NM east of Sydney, and was maintaining 7,000 ft in accordance with its clearance.

The Departures South controller cancelled the 5,000 ft altitude restriction for the departing B737, and issued a clearance for the aircraft to climb to Flight Level 280. The 5,000 ft restriction would have assured separation with the inbound B737. When the altitude restriction was removed, the controller relied on monitoring the flight paths of both aircraft and intervening, if necessary, to maintain separation.

When the departing B737 turned right to track 144 degrees in accordance with the SID, there was a breakdown in separation between the two aircraft. Separation was reduced to 2.5 NM horizontally and 500 ft vertically, whereas the required standard was either 3 NM or 1,000 ft. Traffic information was passed to the crew of the departing B737, who sighted the other B737 while passing behind it.

The Departures South controller was relatively inexperienced, having held a control rating in the Sydney Terminal Control Unit for only three weeks. The controller was distracted from the monitoring role by coordination activities with Bankstown control tower, and by radio transmissions to other aircraft. The controller also considered himself to have been fatigued as a result of local rostering practices.

Safety Action

As a result of this investigation, and a number of similar occurrences, the Bureau of Air Safety Investigation issued a report (B98/90) of an investigation of systemic issues at the Sydney Terminal Control Unit. Nine recommendations were made in the report, the following four of which are considered valid for this investigation:

Airservices Australia review the application of the "teams" concept within the Sydney Terminal Control Unit to ensure that teams are resourced appropriately and that there is an ongoing commitment to the provision of adequate training in order to achieve a high level of controller proficiency and standardisation."

Airservices Australia ensure that adequate refresher training is undertaken by controllers in order to provide for high levels of controller proficiency and standardisation and so that the integrity of safety cases, in which refresher training is deemed to be a mitigating strategy for identified hazards, is maintained."

Airservices Australia reassess the human factor hazard analysis for both Stage One and Stage Two of the 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."

Airservices Australia consider restructuring the current roster operating in the Sydney Terminal Control Unit 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."

General details
Date: 12 June 1998   Investigation status: Completed  
Time: 0925 hours EST    
Location   (show map): 28 km E Sydney, (VOR)    
State: New South Wales   Occurrence type: Loss of separation  
Release date: 18 June 1999   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-TAI  
Serial number 23483  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Sydney, NSW  
Departure time 1125 hours EST  
Destination Melbourne, VIC  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration FODGX  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Noumea, New Caledonia  
Departure time 0633 hours EST  
Destination Sydney, NSW  
Last update 13 May 2014