On 1 July 2010, an Aeronautica Macchi S.P.A. AL60 aircraft, registered VH-ELI (ELI), departed Devonport, Tasmania (Tas.) for Portee Station, South Australia (SA) with planned refuelling stops at King Island, Tas. and Hamilton, Victoria (Vic.).
While enroute from King Island to Hamilton, the crew observed low cloud along the track and diverted to Mount Gambier, SA to refuel. After departing Mount Gambier, the crew observed that the left fuel tank gauge was indicating half full. The crew discussed the situation and elected to continue the flight. Also, the directional gyro had to be aligned twice by the crew due to gyroscopic precession. As a result, the aircraft diverted to the left of the planned track by about 2-4 km. The crew commenced correcting the track when an inbound Pilatus Aircraft Ltd. PC-12/45 aircraft, registered VH‑FDK (FDK), passed to the left in close proximity.
It was estimated that the distance between the two aircraft was between 5 and 15 m horizontally and about 20 ft vertically.
While the operator of FDK determined that their pilot had complied with the required procedures, they advised the Australian Transport Safety Bureau (ATSB) that they will be conducting an internal education to remind pilots that maintaining a lookout and the use of radio telephony procedures are the primary tools used for traffic separation, supported by the traffic alert and collision avoidance system (TCAS).