Operation Close Encounter: the RAAF Williamtown radar alert

June 1983. Something was showing up on the screens at Mascot. Senior air traffic controllers at the Sydney airport's Area Approach Radar Centre had been noticing unidentified contacts since earlier in the month. They were "moving like aircraft". Most sat between 70 and 150 nautical miles north of Sydney.

The numbers were strange. The RAAF file would record "alleged speeds of 1100-6500 km/h that suggested high altitude". Yet no sonic booms were reported.

30 June 1983. No. 3 Control and Reporting Unit, known as 3CRU, at RAAF Base Williamtown near Newcastle launched an operation. Its name was Close Encounter. By 1 July, two Mirage interceptors stood on "Alert 2", "the second highest level of alert". 3CRU kept a radar watch around the clock. But the contacts never appeared on 3CRU's own radar. Nor on Williamtown's SURAD radar. Only Mascot could see them.

Three senior air defence controllers were sent to Sydney. One of them, a squadron leader, asked whether anyone had compared the contacts on the Mascot screens with those in a "workshop across the corridor". The tests that followed were decisive. "The unidentified objects reported by Sydney were generated entirely by radar interference known colloquially as 'running rabbits'".

According to a later summary of the file, the team compared raw receiver data with the processed display. The processing system had been turning interference into aircraft-like tracks. The contacts showed "a slight clockwise spiral", the known signature of the effect. The Bawdsey Radar Museum puts it simply: "Electrical interference from nearby radar stations would show up on the screen as a series of very close dots".

Squadron Leader K.A. Keenan wrote the report. He tallied 66½ days of overtime, about 1,000 km of staff-car travel, and a C-130 Hercules that "may have been diverted to Sydney airport" to deliver one controller. "The lines of communication, extending as they did across the width of an entire corridor, seem to have been insufficient for the purpose," he wrote. The contacts "elicited puzzlement rather than belief". By one account, the alert was stood down on 4 July.

28 December 2016. The Newcastle Herald printed a different story. Geoff Masters said he watched from Tarro with his son: "My son and I both watched this event." He described a "typical flat saucer shape". "The jets came over towards my home in an attempt to chase or maybe force a UFO to land."

"It was like watching a game," he said. "When the jets got too close, this UFO just changed position in the blink of an eye." It became "a comedy of cat and mouse for close on 10 minutes". Then the jets headed back to base, and "the UFO sped off north at a speed you could not describe." He also spoke of reports that a UFO "buzzed Amberley Raaf Base in Queensland on the same night".

The file was marked "restricted". The National Archives of Australia released it under the 30-year rule, and it made the papers in August 2012, alongside other cases such as the lights over Bendigo and a "disc shaped" light at Imbil. In 2020, News of the Area called it the only official close encounter in the base's 80-year history.

The two records do not match. The papers describe a radar-only alert, with Mirages readied but no recorded flight, while Masters gave no date and his chase is not in the file. The 2020 report wrote that the jets were "scrambled", which conflicts with earlier wording. No source has been found for the Amberley claim. The official answer is running rabbits, while Masters' story, told 33 years later, has never been matched to the file.