On the evening of 21 October 1978, 20-year-old pilot Frederick Valentich took off from Moorabbin Airport in a single-engine Cessna 182.
His planned flight would take him across Bass Strait to King Island.
He never arrived.
Shortly before radio contact was lost, Valentich reported an unidentified aircraft above him. His final transmission—and the strange sounds that followed—turned an aviation disappearance into one of Australia’s most debated mysteries.
A Routine Flight into Darkness
Valentich left Moorabbin at about 6.19 pm in the blue-and-white aircraft registered VH-DSJ.
As darkness approached, he flew south-west along the Victorian coast before heading across Bass Strait.
At approximately 7.06 pm, Valentich contacted Melbourne Flight Service and asked whether any military aircraft were operating nearby.
He was told there was no known traffic in his area.
Valentich then described a large aircraft with four bright lights. He said it appeared to pass above him at high speed before approaching again from another direction.
“It Is Hovering and It’s Not an Aircraft”
During the exchange, Valentich attempted to describe what he could see.
He reported a long, shiny or metallic object that seemed to be orbiting above him. He also said his engine was running roughly.
The controller asked him to identify the aircraft.
Valentich replied with words that would become famous: “It isn’t an aircraft.”
Another transmission has often been rendered as, “That strange aircraft is hovering on top of me again.”
The radio exchange ended with approximately 17 seconds of unexplained metallic or scraping sounds.
Then there was silence.
The Search of Bass Strait
A large air and sea search began, covering thousands of square kilometres.
No confirmed wreckage, emergency beacon, oil slick or trace of Valentich was found.
The Cessna had enough fuel to remain airborne well beyond the time radio contact was lost, but it never appeared on King Island or at another airfield.
The official investigation could not determine what had happened.
The aircraft and its pilot remain missing.
Theories About the Disappearance
The most dramatic theory is that Valentich encountered an extraterrestrial craft and was somehow taken with his aircraft.
There is no physical evidence proving an alien encounter, although Valentich’s own words made the theory almost inevitable.
More conventional explanations have also been proposed.
Valentich may have become disoriented while flying over dark water. A pilot who unknowingly enters a descending spiral can mistake stars, reflected lights or even the aircraft’s own lights for another object.
Some researchers have suggested that he saw a bright planet or stars distorted by atmospheric conditions. Others believe he misidentified conventional aircraft.
Another theory proposes that Valentich staged his disappearance, but investigators found no convincing evidence that he safely landed elsewhere or began a new life.
Questions About the Flight
The investigation discovered uncertainty about Valentich’s reason for travelling to King Island.
Different people understood that he was collecting either passengers or crayfish, but neither purpose was confirmed.
Valentich was also relatively inexperienced and had previously failed some aviation examinations. These facts are relevant to possible pilot error, but they do not prove what happened.
They certainly do not explain why no confirmed wreckage was recovered.
An Unresolved Aviation Mystery
The surviving radio transcript makes the Valentich case particularly haunting.
It records a young pilot trying to understand something he believed was moving around his aircraft. Whether that object was real, misidentified or produced by disorientation may never be known.
Bass Strait can be unforgiving, and a small aircraft could disappear beneath its waters without leaving an easily found trace.
Yet the final report of strange lights, the failing engine and the metallic sounds continue to separate this case from an ordinary aviation accident.
Frederick Valentich and VH-DSJ vanished together, leaving behind a final conversation—but no final answer.