The Australian Transport Safety Bureau (ATSB) has released a report into an incident that saw two civilian passenger aircraft heading towards each other in military-controlled airspace near RAAF Amberley last year.
The 11 October 2018 incident occurred when a Qantas 737-800, registration VH-VZD, was on descent to Brisbane Airport through military-controlled airspace near RAAF Amberley 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 RAAF currently operate separate air traffic management systems at Brisbane and Amberley. As a result, in this scenario traffic information had to be shared manually.
Due to thunderstorms in the area, 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.
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 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 1,000 feet vertically.
“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.