The pilot of a Saab Aircraft AB SF-340B (Saab), on final to runway 16R at Sydney airport, was instructed by the aerodrome controller (ADC) to turn right heading 240 degrees M due to an unidentified aircraft in the control zone. The unidentified aircraft was observed to turn north and pass the Saab with 2 NM lateral and 400 ft vertical displacement. The required separation standard was either 3 NM laterally or 1,000 ft vertically. The unknown aircraft was subsequently identified as a Piper Aircraft Corporation PA-23-250 (Aztec). The Aztec pilot had entered the Sydney control zone without a clearance, resulting in an infringement of separation standards.
The Aztec pilot had intended to conduct a visual flight rules (VFR) flight from Bankstown, located 9.5 NM west of Sydney, to Grafton. He had recently purchased the Aztec and this was the first significant trip in that aircraft. The pilot had previously flown a Beech Baron and had completed a flight check on the Aztec.
Flights under the VFR conducted below 10,000 ft required a pilot to operate in the following meteorological conditions:
- flight visibility greater than 5,000 m;
- clear of cloud when in a general aviation control zone; and
- 1,500 m horizontally and 1,000 ft vertically from cloud while en route.
The Bankstown terminal area forecast, issued at 0433, covering the period from 0600 to 1900 Eastern Summer Time forecast a flight visibility of 5,000 m in smoke and a few (1 to 2 OKTAS) clouds at 3,000 ft. The forecast indicated that visibility was expected to increase to greater than 10 km by mid afternoon. The actual meteorological conditions reported at Bankstown during the morning of the occurrence were:
- 0900: westerly wind at 9 kts with visibility of 8,000 m, no cloud below 12,500 ft and temperature of 18 degrees C;
- 0900 report was amended at 0919: westerly wind at 9 kts with visibility of 3,000 m in smoke, no cloud below 12,500 ft with the sky obscured and temperature of 18 degrees C;
- 0930: south-westerly wind at 6 kts with visibility of 6,000 m, no cloud below 12,500 ft and temperature of 18 degrees C;
- 1000: wind was calm with visibility of 7,000 m no cloud below 12,500 ft and temperature of 19 degrees C; and
- 1030: north-westerly wind of 4 kts with visibility of 7,000 m, no cloud below 12,500 ft and temperature of 20 degrees C.
The actual reported weather conditions at Sydney during the morning were:
- 0900: southerly wind at 7 kts with visibility of 4,000 m in smoke and scattered (3 to 4 OKTAS) clouds at 1,600 ft and temperature of 18 degrees C;
- 0920: southerly wind at 7 kts with visibility of 6,000 m in smoke with a few (1 to 2 OKTAS) clouds at 4,500 ft and temperature of 18 degrees C;
- 0930: southerly wind at 7 kts with visibility of 6,000 m in smoke with a few (1 to 2 OKTAS) clouds at 4,500 ft and temperature of 18 degrees C; and
- 0955: south-easterly wind at 7 kts with visibility of 7,000 m in smoke with a few (1 to 2 OKTAS) clouds at 4,500 ft and temperature of 19 degrees C.
Weather conditions at the time were visual meteorological conditions that had been affected by bushfires in the Sydney basin.
The pilot had delayed departing from Bankstown in anticipation of the weather conditions improving and subsequently departed at about 0945. Immediately after take-off, while the pilot was still monitoring the Bankstown ADC frequency, the right engine commenced to `run rough'. The pilot reduced power on that engine and attempted to identify the cause of the problem. The pilot decided to return to Bankstown as the situation could not be rectified and the aircraft was vibrating. As he manoeuvred to return, the flight visibility was such that the pilot could not see Bankstown airport. He was aware of the aircraft's proximity to the Sydney control zone and reported that he was about to call Sydney air traffic control for a clearance when he was advised by the departure south controller that the Aztec had infringed the control zone.
The Aztec pilot had selected code 1200, the nominated code for a VFR flight operating in non-controlled airspace (and not participating in a radar information service) and was operating the aircraft's transponder.
The Sydney Aerodrome and Director West controllers saw, on the air traffic control radar, that the Aztec was in the control zone, northwest of Canterbury racecourse, and likely to conflict with aircraft on final to runway 16R. The ADC instructed the pilot of the Saab to turn right to avoid the Aztec. The pilot of another aircraft was similarly instructed.
Before the pilot could return to Bankstown, the right engine on the Aztec started to operate normally. The pilot decided to continue the flight and tracked to the north to vacate the control zone and to join the VFR lane. The flight continued uneventfully to Coffs Harbour where the pilot refuelled the aircraft. Subsequently, after take-off from Coffs Harbour, at approximately 300 ft, the right engine surged and the pilot landed the aircraft on the remaining runway. The pilot taxied the aircraft to a hangar for maintenance action and on reaching the hangar the left engine stopped. Inspection by a licensed aircraft maintenance engineer (LAME) found that the cooling flaps on both engines were inoperative and had caused the engines to overheat. The LAME re-rigged the cowl flaps for maximum cooling and a subsequent engine ground run confirmed normal operation.