By Simon Hradecky, created Tuesday, Jan 17th 2017 17:19Z, last updated Tuesday, Jan 17th 2017 17:19Z A Virgin Australia Embraer ERJ-190, registration VH-ZPJ performing flight VA-1615 from Melbourne,VI to Mildura,VI (Australia) with 81 passengers and 5 crew, was on a visual approach to Mildura's Aerodrome, which was uncontrolled. Prior to being handed off from approach the crew had been advised there were two other aircraft on approach to Mildura, one showing an arrival time past ZPJ was not considered a possible hazard, the crew verified with the other aircraft via radio, that this aircraft, a light twin, would arrive past them, too. The aircraft joined a left downwind, turned based and was about to turn final, when the crew received a TCAS Traffic Advisory (TA) showing the threat to their right. The crew identified an aircraft, nearly stationary on their windscreen, on their right hand side and high above the sky line with a fast enclosure rate.



The ATSB released their final report describing the following events:



The PM on board ZPJ contacted the other traffic on the radio and requested their intentions. The other traffic was XGA, which was leading XGY back to Mildura Airport for a straight-in approach to runway 09. When the pilot of XGA responded that they were tracking for a straight-in approach to runway 09, the PM assessed they were on a collision course on their present track. They also recognised that there would be a potential risk of collision if both aircraft performed a go-around to the south of the main runway. Therefore the PM responded to the pilot of XGA to immediately turn and remain south of the airport. The pilot of XGA identified ZPJ ahead of them on approach to runway 09 and responded that they would discontinue their approach and manoeuvre to the south of the airport.



The PF on board ZPJ decided to discontinue their approach to land on runway 09, as they were too late for their turn onto final and therefore not in a stabilised condition.4 However, the PM indicated to the PF that they could not execute a go-around manoeuvre because there was another aircraft joining the circuit on crosswind (the light twin-engine aircraft). The PF decided that continuing the approach to land was not an option and therefore executed the go-around to the south of runway 09, maintained separation from the other traffic on crosswind and then landed from the subsequent circuit. During the go-around manoeuvre, the aircrafts TCAS detected XGA pass about 200 ft above and 0.125 NM behind ZPJ.



The ATSB released their findings:



- The pilot of XGA was probably not monitoring Mildura CTAF when the PM on board ZPJ broadcast joining the Mildura circuit.



- The flight crew of ZPJ did not detect the broadcast from XGA that they were intending to join a straight in approach to runway 09.



- After a separation strategy was agreed, XGA continued to close on ZPJ to a closest point of approach of 0.125 NM behind and 200 ft above ZPJ when ZPJ started their go-around.



- Both aircraft made the required broadcasts on the CTAF.



- The flight crew on board ZPJ were cued to the conflict by their TCAS traffic advisory alert.



- The pilot on board XGA was cued to the conflict by the radio broadcast from ZPJ.



The ATSB analysed:



The AIP directs pilots to the minimum required radio broadcasts when operating at non-controlled aerodromes and the pilots of ZPJ and XGA complied with these requirements. However, it is likely that the pilot of XGA was not on the Mildura CTAF when the PM on board ZPJ made a broadcast that they were joining the Mildura circuit. When the pilot of XGA switched to the Mildura CTAF they were initially occupied with communicating with another public transport aircraft inbound from the north and considered this aircraft to be their only potential conflict. It could not be determined why the flight crew on board ZPJ did not comprehend the presence of a potential conflict from this radio traffic. However, the flight crew of ZPJ had previously dismissed these two aircraft (XGA and XGY) as a potential conflict for their arrival.



After ZPJ turned onto the base leg for runway 09, the PM made a base radio broadcast. It could not be determined why the pilot of XGA did not comprehend the presence of a potential conflict from this broadcast. However, the investigation could not rule out the possibility that other aircraft operating at Mildura or Wentworth made broadcasts which interfered with one or several of the broadcasts made by ZPJ or XGA.



Shortly after the base leg radio broadcast from the PM in ZPJ, the flight crew were alerted to the presence of XGA by a TCAS TA aural alert. At this time ZPJ was below 900 ft and therefore TCAS resolution advisory was inhibited. However, the TCAS visual display of the relative position of XGA cued their visual search and facilitated a quick identification. XGA appeared to the flight crew on board ZPJ as stationary against a background of sky. Therefore, to the pilot of XGA, ZPJ was probably against a more complex background with no relative motion, contributing to the difficulty for the pilot of XGA to detect ZPJ before they were alerted by the radio call by ZPJ.



The radio broadcast from the PM on board ZPJ directed to the traffic inbound to Mildura from the west alerted the pilot of XGA to the presence of other traffic and cued them to search for the conflict. The PM on board ZPJ then directed the pilot of XGA to turn immediately away to the south to avoid a potential collision either during their turn onto final approach or in the event that both aircraft attempted a simultaneous go-around manoeuvre on the south side of runway 09.



After receiving an acknowledgement from the pilot of XGA, the flight crew on board ZPJ turned their attention to the execution of their go-around manoeuvre as their turn onto the final leg of the circuit was late due to their preoccupation with monitoring XGA. However, during their turn to join the upwind circuit leg for runway 09 on the south side of the runway, XGA continued to converge to a closest point of 0.125 NM behind and about 200 ft above ZPJ before making an abrupt turn to the south. This was the result of the intention of the pilot flying XGA to join the upwind leg of the circuit to the south of runway 09, before they realised that ZPJ was also conducting a go-around from their approach.



Overview Map of Traffic Scenario (Graphics: ATSB):





Detail Map of developing conflict (Graphics: ATSB):



