Two Boeing 737 jets – one operated by Qantas and the other by Virgin Australia – flew directly towards each other on the same flight path over Brisbane Airport and at one point were separated by less than 200 metres, according to an official report yesterday.
It happened as civilian and military air traffic controllers worked hard to co-ordinate a last-minute weather-related change as thunderstorms tore through the area.
A report yesterday on the incident in October 2018 said a Qantas 737 inbound to Brisbane from Melbourne flew towards an outbound Virgin flight headed to Proserpine. The jets came within 2.1 nautical miles of each other horizontally – and just 650 feet (198 metres) vertically – breaching aviation separation rules.
The two aircraft were operating in the same airspace but on different frequencies, with one plane controlled by RAAF Amberley (military) air traffic control (ATC) and the other by Brisbane (civil) ATC.
Source: ATSB
The airspace sectors for the Brisbane Terminal Control Unit (TCU) had been moved out of their usual configuration because of the World Parachuting Championships at Runaway Bay (about 65km south-south-east of Brisbane Airport). As inbound and outbound tracks of aircraft were tracked around the parachute operations, one controller was controlling all departures and approaches in the southern area. Due to the weather front approaching, the parachuting championships were put on hold.
About five minutes before the incident, just after 2pm, the Brisbane airspace was returned to a more standard configuration, being that the departures controller controlled all departures to the south and north. The Brisbane approach south controller was controlling all aircraft approaching from the south.
This change, however, was not communicated to Amberley ATC.
A report by the Australian Transport Safety Bureau (ATSB) using data from Airservices Australia said the incident demonstrated “the importance of communication and coordination between air traffic controllers operating in separate, yet adjacent airspace, as well as the need for a clear understanding of the responsibility for separation assurance when operating without a shared traffic picture”.
The ATSB released the result of is final investigation report into the 11 October 2018 incident, where a Qantas 737-800, registration VH-VZD, was on descent to Brisbane Airport through military-controlled airspace near Amberley Air Force Base, while a Virgin Australia 737-800, VH-YFW, which had departed Brisbane Airport, was approaching Amberley airspace on a reciprocal track.
Airservices Australia, which operates Australia’s civil air traffic management system, and the Royal Australian Air Force, which is responsible for controlling military airspace, such as around major air bases, currently operate separate air traffic management systems at Brisbane and Amberley. As a result, in this scenario traffic information had to be shared manually.
Thunderstorms in the area meant the Virgin aircraft was flying air traffic control (ATC)-assigned radar headings, rather than using a procedural standard instrument departure. As the Virgin aircraft approached Amberley airspace, the Brisbane departures controller (operating from Airservices’ Brisbane terminal control unit at Brisbane Airport) provided an identification of the Virgin aircraft to the Amberley approach controller, who advised that there was an aircraft on an inbound air route.
Brisbane replied that the Virgin aircraft would soon be turning right, and thus would avoid Amberley airspace; however when advised to turn right, the crew of the Virgin aircraft replied that due to the weather they wished to continue on their current heading for another 70 or 80 nautical miles.
It was around this time that the Virgin aircraft entered Amberley airspace without a hand‑off from Brisbane ATC and without instructions to the crew to change to Amberley frequency. Prior to this, the Brisbane terminal control unit had not advised Amberley ATC of a changed terminal control unit configuration. This delayed Amberley ATC in being able to contact the correct controller position at the Brisbane terminal control unit to inform them of the inbound aircraft, thus reducing the opportunity for Amberley ATC to resolve the impending conflict.
As the ASTB puts it, dryly: “Once appropriate communication between Amberley and Brisbane ATC was established, the Virgin aircraft was transferred to the Amberley frequency, and the two aircraft were diverted away from each other. The successful recovery of separation illustrates the effectiveness of the conflict resolution training received by air traffic controllers in loss of separation events.”
The ATSB’s investigation found the aircraft had incurred a vertical and lateral loss of separation with a minimum-recorded distance between the aircraft of 2.1 nautical miles horizontally and 650 feet vertically, respectively, where the required separation was 3 nautical miles horizontally or 1000 feet vertically. (Both aircraft were fitted with traffic collision avoidance systems which would have assisted in providing separation instructions to their flight crews in the event ATC were unable to resolve the situation.)
“This investigation highlights the importance of clear communication and coordination between air traffic controllers operating in different, yet immediately adjacent airspace, and the need for a clear understanding of the responsibility for separation assurance, especially when operating without a shared traffic picture,” ATSB Director Transport Safety Dr Stuart Godley said.
As a result of the incident, both Brisbane and Amberley ATC have taken a number of steps to improve communication between their two systems.
As a result of this occurrence, Airservices Australia (civil air traffic control) advised the ATSB that they are taking the following safety actions:
- Implementing airspace releases that control the risk that short notice deviations present across the non-linked systems.
- Deployed dedicated communication lines between Amberley ATC and Brisbane departures south.
As a result of this occurrence, RAAF (military) air traffic control has advised the ATSB that they have taken the following safety actions:
- A communications line to Brisbane departures south has been established and commenced operational use.
- The relevant parties are working together to implement a solution to ensure separation assurance between Brisbane departing aircraft and Amberley traffic during weather diversions.
- Amberley have submitted a documentation change to Airservices Australia to extend the weather colour coding to include the Brisbane TCU/Amberley approach interface.
Edited by Peter Needham
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