Loss of separation involving a Cessna 550, VH-WNZ and Boeing 767-338ER, VH-OGK, 11 km north-east of Brisbane Aerodrome, Queensland, on 22 July 1997

VH-WNZ was conducting a training flight, and the pilot had advised the Tower of his intention to conduct a simulated engine failure after take-off. The aircraft departed on an initial assigned radar heading of 060 degrees at 1710.40 EST.

VH-OGK was assigned an IBUNA 1 Standard Instrument Departure (SID), departed at 1712.30 EST, and had been instructed to remain on Tower frequency. While turning right as per the SID to heading 180 M, OGK passed behind WNZ. Separation between the aircraft reduced to 2.5 NM horizontally and less than 500 ft vertically. The required separation was 3 NM and 1,000 ft.

Investigation revealed that the aerodrome controller (ADC) did not adequately plan the departure of three aircraft, including WNZ and OGK. An arriving aircraft led to his decision to expedite the departure of OGK, thus compromising the separation between these aircraft. The ADC's decision to retain OGK on Tower frequency until instructed to transfer delayed the opportunity for the departures controller to issue instructions to OGK to ensure separation was maintained.