On 4 April 2007 at about 0809 Eastern Standard Time a Boeing
Aircraft Company 737-8FE registered VH-VON was inbound to Sydney,
NSW from Melbourne, Vic. on descent to 6,000 ft and an Airbus
A330-342X, registered B-HLW was departing Sydney for Hong Kong on
climb to 7,000 ft. The distance between the aircraft reduced to 1.9
NM horizontal and 600 ft vertical separation. Separation standards
as specified in the Manual of Air Traffic Services (MATS) required
the provision of either 3 NM horizontal or 1,000 ft vertical
separation between the aircraft. There was a breakdown of
separation.
The loss of separation occurred as a result of the separation
that was planned by the air traffic control officer being based on
an incorrect cleared flight level (CFL) that had been entered into
the controller's air situation display (ASD). The investigation
concluded that this data entry error occurred within 2 minutes of
the air traffic controller assuming responsibility for the control
position, and that the reconfiguration of the in-use console by the
controller during that time increased the risk of the controller
being distracted from the traffic separation task.
