Operation Close Encounter — RAAF Base Williamtown

Operation Close Encounter was initiated in June 1983 following reports of unidentified radar contacts at the Area Approach Control Centre (AACC) in Mascot, Sydney. The Department of Aviation (DOA) reported that these contacts moved like aircraft and were likely man-made. In response, RAAF Base Williamtown was directed to investigate. 3 Control and Reporting Unit (3CRU) established round-the-clock surveillance and placed Mirage interceptors on alert. An investigative team of Air Defence Controllers was dispatched to the AACC to analyze the radar data. The team discovered that the reported contacts were not physical objects but were instead generated by radar interference within the Sydney Route Surveillance Radar (RSR). This interference, colloquially known as 'running rabbits,' was confirmed through technical testing of the radar receiver chain. The investigation concluded that the AACC operators had been misinterpreting this interference as rapidly moving aircraft. The operation resulted in significant accrued overtime for 3CRU personnel and disrupted planned maintenance and training. The report emphasizes the importance of data-linking radar sensors and conducting thorough technical investigations before escalating to air defence alerts. The operation was officially stood down on July 4, 1983, after a conference with DOA technical staff confirmed the findings.