At about 1525:34 Eastern Standard Time (EST) on 5 May 2002, a Piper PA-28-161 aircraft, registered VH-IBK, and a Socata TB-9 aircraft, registered VH-JTV, collided on final approach to Bankstown airport, New South Wales. General Aviation Airport Procedures (GAAP) were in operation at the time, and aircraft were using simultaneous contra-rotating circuits onto parallel runways (contra-circuits) in the 29 direction. Under GAAP, pilots operating in visual meteorological conditions were responsible for aircraft separation when airborne in the circuit. Air traffic controllers were responsible for providing sequencing, traffic information to pilots, and runway separation.
The pilot of IBK had been issued with a clearance to land on runway 29 Centre (29C) from a right circuit by the aerodrome controller one (ADC1). The pilots of JTV had been issued with a clearance to conduct a touch and go landing on runway 29 Left (29L) from a left circuit by the aerodrome controller two (ADC2). The ADC1 provided traffic information to the pilot of IBK, but had not informed ADC2 that IBK was using runway 29C. Consequently, ADC2 was not aware that IBK was using runway 29C and did not provide traffic information to the pilots of JTV. This omission was not considered to be a factor in the accident as the pilots of JTV saw IBK on the base leg. The pilot of IBK reported to ADC1 that he had sighted the traffic, but the investigation was unable to determine whether he saw JTV or VH-SVK, which was following JTV in the southern circuit.
The two aircraft collided on, or near, the extended centreline of runway 29L about 1,700 m from the runway threshold. The collision occurred as IBK crossed the extended centreline of runway 29L on a heading about 25 degrees to the left of the extended runway centreline. At the time of the collision, JTV was probably aligned with the extended centreline of runway 29L. None of the three controllers on duty in Bankstown tower at the time observed the accident, nor were they required to be monitoring the position of IBK and JTV at the time.
The collision resulted in damage to the left stabilator and the separation of the vertical stabiliser of IBK, which resulted in the aircraft becoming uncontrollable. IBK subsequently impacted the ground in an industrial area to the southeast of the airport and the four occupants were fatally injured. There was no fire. Impact forces destroyed the aircraft. Following the collision, the instructor pilot landed JTV safely on runway 29L at Bankstown and the two occupants were uninjured.
There was no evidence that fuel contamination, mechanical malfunction, structural failure, a birdstrike, or meteorological conditions were factors in the occurrence.
The distance between the centrelines of runway 29C and runway 29L was 107 m. In 1979, the standard for contra-circuit operations at GAAP airports was specified as a minimum distance of 213 m between runway centrelines. The aviation safety regulator subsequently granted a concession to permit GAAP operations at Bankstown on to runways with a minimum separation of 107 m between centrelines. This concession was intended to be a short-term measure until the completion of runway upgrading work, which occurred in the mid-1980s. The regulator changed the 213 m standard to a recommended practice in 1989.
A significant proportion of GAAP operations at Bankstown involved contra-circuit operations onto parallel runways 107 m apart, with about 12 per cent of all arriving aircraft (or about 30 per cent of arriving aircraft from the northern circuit) landing on runway 11C/29C. At the same time that these aircraft were landing on runway 11C/29C, there were generally multiple aircraft operating in the southern circuit and landing on runway 11R/29L. The use of runway 11C/29C had probably increased during the period since the implementation of GAAP at Bankstown in 1980.
There was no operational requirement for the pilot of IBK to use the centre runway. However, it was common practice for pilots of aircraft based on the southern side of the airport to make such requests on arrival into the circuit to minimise taxi time. It was also common practice for Bankstown controllers to approve such requests during contra-circuit operations.
The critical event leading to the midair collision was IBK passing through the extended centreline of runway 29C into the flight path of JTV at or about the centreline for runway 29L. The investigation estimated that IBK passed through the runway 29C centreline at about 1525:29, 5 seconds prior to the collision. The reason why IBK passed through the extended centreline of runway 29C could not be determined.
The investigation concluded that there were insufficient visual cues available for a pilot in one circuit to reliably assess the collision potential of an aircraft in the opposing circuit when both aircraft were conducting contra-circuit operations to parallel runways that were 107 m apart.
The primary mitigator in place at Bankstown to prevent a collision involving two aircraft conducting contra-circuits to runways 107 m apart was the provision by controllers of traffic information to the pilots. Research has indicated that the provision of traffic information will increase the probability of a pilot detecting another aircraft. However, for the opposite-base traffic situation, there was insufficient evidence to determine the extent of the mitigator's influence on collision risk.
The accident was the first mid-air collision at Bankstown since 1975. However, the investigation considered that the estimated risk level for midair collisions at Bankstown probably exceeded the scrutiny line of the Civil Aviation Safety Authority's acceptable risk criteria. For a general aviation airport such as Bankstown, this meant the risk levels were at the upper end of the 'as low as reasonably practical' region. This situation placed an onus on those agencies responsible for managing the risk at Bankstown to ensure that appropriate risk management processes were in place. The air traffic service provider, Airservices Australia, had implemented a safety management system, but at the time of the accident there were limitations in the processes for identifying and monitoring hazards at major general aviation airports such as Bankstown.
In late 2000 Airservices decided to prepare risk management plans for all control towers throughout Australia, including Bankstown. There was no regulatory requirement for these plans. The risk management plan for Bankstown Tower was commenced in January 2003 and completed in February 2003. In December 2003, Airservices modified its procedures for Bankstown so that, where aircraft involved in contra-circuits were likely to be at base or final legs at approximately the same time, the use of the centre runway would be denied.
Related Documents: | Media Release |
|Date:||05 May 2002||Investigation status:||Completed|
|Time:||1525 hours EST|
|Location:||2.3 km ESE Bankstown, Aero.|
|State:||New South Wales||Occurrence type:||Airborne collision|
|Release date:||04 May 2004||Occurrence class:||Airspace|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
Aircraft 1 details
|Aircraft manufacturer||S.O.C.A.T.A.-Groupe Aerospatiale|
|Type of operation||Flying Training|
|Damage to aircraft||Substantial|
|Departure point||Bankstown, NSW|
|Departure time||1515 hours EST|
|Role||Class of licence||Hours on type||Hours total|
Aircraft 2 details
|Aircraft manufacturer||Piper Aircraft Corp|
|Type of operation||Private|
|Damage to aircraft||Destroyed|
|Departure point||Wagga Wagga, NSW|
|Departure time||1334 hours EST|
|Role||Class of licence||Hours on type||Hours total|