On the evening of 7 October 2013, the pilot of a Cessna 172 aircraft, registered VH‑NUU (NUU), commenced night circuits at Archerfield Airport, Queensland. He reported that there were also four other aircraft and a helicopter conducting night circuits at the time. The pilot reported that the aircraft in the circuit were flying a ‘modified’ due to a strong tailwind and to make allowances for a helicopter that had been conducting stop-and-go circuits.
At the same time, the pilot of a Beech F33A aircraft, registered VH‑ZBZ (ZBZ), inbound to Archerfield, was advised by air traffic control that there were four or five aircraft in the circuit area. ZBZ joined the circuit between an aircraft on downwind and another on upwind. The pilot of ZBZ reported that he had the aircraft in front of him (NUU) sighted on downwind and extended the downwind leg to maintain separation with NUU.
NUU turned onto base and about 20 seconds later, the pilot of ZBZ also broadcast that he was turning onto base. Soon after, the pilot of ZBZ broadcast that he was established on final. At that time, he had sighted an aircraft well ahead on late final and believed it was NUU. The pilot of NUU immediately broadcast that he was on final.
The pilot of ZBZ then saw NUU below his aircraft. The pilot of ZBZ conducted a go‑around and NUU continued the approach.
Airservices Australia surveillance data indicated that the vertical separation reduced to 300 ft.
Maintaining a vigilant lookout at all times and standardisation of the circuit pattern is important for safe operations in the vicinity of non-towered aerodromes.