On 26 August 2013, a flight instructor and student pilot were conducting night circuits in a Cessna 172 aircraft, registered VH‑RQZ (RQZ), at Archerfield Airport, Queensland. There were also two other aircraft conducting circuits. The student pilot of RQZ broadcast a call on the CTAF downwind leg of the circuit for runway 10. The pilot of an Agusta AW139 helicopter, registered VH-ESZ (ESZ), then broadcast an inbound call advising they were 5 NM to the north at 1,400 ft above mean sea level.
The pilot of ESZ reported sighting two other aircraft in the circuit and noted that they were unlikely to come into conflict with ESZ.
The student pilot of RQZ then broadcast a call turning base for a touch-and‑go on runway 10 and stated that they were conducting a simulated landing light failure.
About 15 seconds later, the pilot of an instrument flight rules (IFR) aircraft asked the pilot of RQZ to confirm his position, to which the instructor replied that they were turning onto final. Shortly after, the pilot of ESZ broadcast a call advising that he was on a tight left base for runway 10.
When RQZ was on final, the instructor sighted ESZ on a close base in his 10 o’clock position, about 1 NM away and broadcast a call asking the pilot of ESZ whether he had RQZ sighted, but did not hear any response. He then conducted a go-around to ensure separation with ESZ.
When at about 300 ft above ground level, the pilot of ESZ sighted RQZ in his 4 o’clock position, about 100 ft below and 100 m behind ESZ and instructor of RQZ then broadcast that they were going around. The pilot of ESZ tightened the turn onto final and elected to land on the taxiway parallel to runway 10. He had not received a traffic collision avoidance system (TCAS) alert on any aircraft other than the IFR aircraft.