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.