The pilot of a Turbo Commander reported, that when on short final approach to runway 29 centre (29C) at Bankstown Airport, he saw another aircraft, above and slightly to the left of his aircraft, in close proximity. The pilot of the Turbo Commander conducted a go around. The other aircraft was subsequently found to be a Cessna 152 (C152) flown by a pilot conducting circuit training as part of commercial pilot licence training.
The occurrence happened about 1 minute after evening civil twilight of 1819 Eastern Standard Time. The Aeronautical Information Publication defines that period between evening civil twilight and morning civil twilight as `night'. The Bankstown automatic terminal information broadcast at the time advised that runway 29C was available for all operations on radio frequency 132.8 MHz, the wind direction was 270 degrees M at a speed of 15 kts, with a maximum crosswind of 10 kts and the barometric pressure was 1013 hectopascals.
Due to the onset of twilight, the aerodrome controller (ADC) was transitioning from multiple runway to single runway operation. Runway 29C is the preferred runway for night operations. Traffic disposition at the time was three single-engine aircraft conducting circuit training, two arriving aircraft and one aircraft ready for departure.
The ADC instructed the pilot of the Turbo Commander to join left downwind for runway 29C at 1,500 ft, as the second aircraft in the arrival sequence. The first aircraft in that sequence was an Aero Commander 500, also tracking to join left downwind at 1,500 ft. Both aircraft were operated by the same company. The pilot of the Turbo Commander requested, and was approved by the ADC, to maintain 2,000 ft until sighting `the other company traffic'. The pilot of the Turbo Commander reported to the ADC on a wide downwind at 2,000 ft. The ADC instructed the pilot of the Turbo Commander to descend to 1,000 ft and to follow the company Aero Commander. General Aviation Aerodrome Procedures (GAAP) require a pilot who is instructed to follow a particular aircraft, to sight the other aircraft and to regulate aircraft speed to achieve longitudinal spacing. Those procedures also require a pilot to report to the ADC if they are unable to see, or lose sight of, the aircraft. The pilot of the Turbo Commander requested an update of the position of the Aero Commander ahead and the ADC advised that it is `in your 10 o'clock'. The pilot acknowledged that advice and continued the approach.
Pilots of both instrument flight rule (IFR) and visual flight rule (VFR) category flights operating in a GAAP control zone (CTR) are required to operate in accordance with the VFR. Also, Civil Aviation Regulation (CAR) 163A stated, `When weather conditions permit, the flight crew of an aircraft must, regardless of whether an operation is conducted under the IFR or the VFR, maintain vigilance so as to see and avoid other aircraft.'
Within a GAAP CTR, controllers use sequencing instructions and/or provide traffic information to pilots to assist them to manoeuvre to avoid other traffic. Other than the application of runway separation standards between aircraft during take off or landing, an ADC does not use standards to segregate airborne aircraft.
Pilots of aircraft operating in a GAAP CTR are not required to use the aircraft's secondary surveillance radar transponder. The pilot of the Turbo Commander and the pilot of the Aero Commander were operating their respective transponders. The pilot of the C152 was not operating that aircraft's transponder. The ADC had access to a tower situational awareness display (TSAD), to assist in maintaining situational awareness. The TSAD used radar information from the Australian Advanced Air Traffic System and provided a track history, callsign (or mode A) and altitude if the SSR transponder was operating, and aircraft ground speed. The TSAD was limited in scale and definition and the display monitor was located to the rear of the tower console.
Recorded radar data indicated that the Aero Commander and the Turbo Commander entered the control zone with groundspeeds of 170 kts and 260 kts respectively. The maximum ground speed of the C152 was 110 kts for a short period when mid-downwind. The downwind leg for the Turbo Commander was laterally displaced about twice the distance from the runway centreline, compared with the other aircraft in the circuit, due to the need to descend and also to maintain spacing with the aircraft ahead. The pilot of the Turbo Commander reduced the aircraft's groundspeed while tracking via downwind and base.
The pilot of the C152 reported downwind and was instructed by the ADC to sight and follow the Turbo Commander on a `late wide downwind'. The pilot saw that aircraft and also noted another aircraft on final approach to the runway. Subsquently, the pilot of the C152 lost sight of the Turbo Commander and on late base requested an update of the position of that aircraft from the ADC. As the ADC was responding, the pilot of the C152 saw the Turbo Commander to his right at an altitude slightly below that of the C152. At that stage the pilot of the Turbo Commander commenced the go around and advised the ADC. Recorded radar data showed that just prior to the go around, the Turbo Commander was 200 m west of the C152 and on a converging track. The groundspeed of the Turbo Commander when on final approach was 100 kts; the groundspeed of the C152 on late base was 70 kts.
While the TSAD was available to assist the ADC, it is unlikely to have been of much benefit as that controller needed to visually monitor all aircraft in the circuit. The occurrence reinforces the need for vigilance by both pilots and controllers during GAAP. The pilot of the C152 was required to maintain separation with and to follow the Turbo Commander, but was probably constrained by his limited flying experience. The ADC, having established an arrival sequence, was required to monitor the situation to ensure that it happened as planned. A combination of darkness, the transition to single runway operations and the significantly higher groundspeed of the Turbo Commander, compared with the other aircraft in the circuit at the time, were additional factors that increased the complexity of the situation.
|Date:||25 September 2002||Investigation status:||Completed|
|Time:||1815 hours EST|
|State:||New South Wales||Occurrence type:||Near collision|
|Release date:||15 October 2003||Occurrence class:||Airspace|
|Report status:||Final||Occurrence category:||Incident|
|Highest injury level:||None|
Aircraft 1 details
|Aircraft manufacturer||Aero Commander|
|Type of operation||Air Transport Low Capacity|
|Damage to aircraft||Nil|
|Departure point||Canberra, ACT|
|Departure time||1750 hours EST|
Aircraft 2 details
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Flying Training|
|Damage to aircraft||Nil|
|Departure point||Bankstown, NSW|