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The Valentich disappearance is a mysterious event that occurred on October 21, 1978, in which 20-year-old Frederick Valentich disappeared in unexplained circumstances while piloting a Cessna 182L light aircraft over Bass Strait to King Island, Australia.

During a 125-mile (201 km) “training flight”, Valentich contacted Melbourne air traffic control, saying he “was being buzzed by a UFO with four bright lights about 1,000 feet (300 m) above him.” More reports from Valentich followed; he later noted that his plane’s engine was running roughly, and his last message was “It is not an aircraft.”

No trace of Valentich or his aircraft was ever found, and a Department of Transport investigation concluded that the reason for the disappearance could not be determined.