On 26 August 2011, a Hawker Beechcraft Corporation B200 aircraft, registered VH-MWH (MWH), departed Ivanhoe for Broken Hill, New South Wales. While maintaining flight level 140, the pilot of MWH received a traffic alert and collision avoidance system (TCAS) traffic advisory (TA) on a Regional Express S.A.A.B. Aircraft Corporation 340B aircraft, registered VH-ZRC (ZRC), which had departed Broken Hill for Sydney and was on climb to flight level 170.
At about the same time, while climbing through flight level 130, the crew of ZRC received a TCAS TA, shortly followed by a resolution advisory (RA). As the First Officer (FO) believed they were above MWH, he immediately commenced a climb. Shortly after, the Captain noted that the FO's response was contrary to the RA command to descend and advised the FO, who immediately commenced a descent.
A review of the Airservices Australia radar data indicated that, with both aircraft at flight level 142, lateral separation reduced to 2.2 NM.
This incident highlighted the benefit of TCAS in assisting pilots with traffic awareness and the importance of responding appropriately to a TCAS RA.