The pilot was tracking for left base, runway 22 (about 290 degrees), and was instructed to report abeam the Queen Elizabeth 2 stadium. A twin- engined aircraft, VH-DRB, was descending to 1500 feet from CTA to the south east of Archerfield. The pilot of this aircraft had initially requested a landing on runway 28 but the controller had difficulty in facilitating this request. The controller ultimately instructed VH-DRB to make a visual approach via a wide left base for runway 22, and to follow a third aircraft on final approach.
In VH-JVV, the pilots were monitoring the progress of VH-DRB by radio. The trainee instructor alerted the pilot in command to the position of the other aircraft. An immediate climbing turn was initiated in order to avoid a collision. The controller attempted to confirm that JVV had VH-DRB in sight at about the same time.
The pilot of VH-DRB saw the other aircraft during its avoiding turn. His aircraft was still descending, and the other aircraft was probably hidden from view by his aircrafts nose section, the instrument combing or the right windscreen pillar. He did not take any avoiding action.
The aerodrome controller had not passed traffic information about each other to the two aircraft involved. The warning transmission from the controller was made at the same time as the pilot of VH-JVV reported at QE 2 stadium.
The pilot of VH-DRB originally requested runway 28, and the controller had initially attempted to facilitate this request. In doing so he had not considered the possible track of that aircraft when it was instructed to track for a wide left base for runway 22.
The weather at the time was fine, with a clear sky and unrestricted visibility.