An Australian pilot's disappearance continues to fascinate people decades on.
The pilot told air controllers a mysterious aircraft was flying above him 'playing some sort of game'.
After a final chilling transmission, he was never heard from again and the mystery of his disappearance remains unsolved.
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You can listen to flight service officer Steve Robey reflect on his bizarre conversation with Valentich below:
Frederick Valentich had been flying from King Island off Australia's south coast to Moorabbin, located south west of Melbourne, when he went missing.
The 20-year-old pilot had been flying a small single engine aircraft at night over the water.
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Valentich had been hoping to become a full-time pilot but had been rejected from commercial training and the Royal Australian Air Force.
It also wasn't his first incident, with Valentich having received warnings on previous occasions.
In 1978 Valentich had planned to celebrate an anniversary with his girlfriend on Saturday October 21.
The evening before Valentich informed her that he had planned an evening flight to King Island, not far from Melbourne, and they planned to meet when he got back.
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He took off in a Cessna 182L light aircraft in the evening.
"The thing is just orbiting on top of me"
Valentich soon radioed that he was being followed by another aircraft, reporting four bright 'landing lights' circling above him.
He asked ground control if there was another aircraft in the area, but they replied that there wasn't.
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When they asked him if he was able to get eyes on the aircraft, he said: "It seems to me that he's playing some sort of game he's flying over me three times at a time at speeds I could not identify.
"The thing is just orbiting on top of me also it's got a green light and sort of metallic [like] it's all shiny [on] the outside."
After a while Valentich said the aircraft had 'vanished', but soon after it returned and he sent his final chilling transmission.
The young pilot said: "That strange aircraft is hovering on top of me again. It is hovering and it's not an aircraft."
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Nothing more was heard from him, but listeners reported hearing 'metallic' sounds afterwards.
What really happened to Valentich?
The incident saw UFO conspiracy theorists claiming that the young pilot had been abducted by aliens and his plane destroyed.
A number of explanations have been suggested for Valentich's disappearance, including that he faked his own death.
Another is that he had become disoriented flying in the dark and was flying upside down, meaning that the lights 'above' him were actually the lights of his plane reflected in the sea.
This explanation was dismissed because the plane that he was flying uses a gravity-fed fuel system so could not have sustained upside down flight for long.
A review of the evidence in 2013 suggested that Valentich had been confused by an illusion of a tilted horizon, where you think the aircraft is not level but it is.
This meant he tried to compensate when there was no need to and mistakenly sent the plane into a downward spiral called a 'graveyard spin'.
A 'graveyard spin' can create the illusion that the plane is level, and in some cases can even make a pilot think that they are spinning the other way when they correct.
As for the 'bright lights' orbiting above him, these may have been the planets Mars, Venus, and Mercury, and the star Antares.
A search and rescue operation was launched but failed to find Valentich.
In 1983 an official investigation found a fragment of an Cessna 182 aircraft which was determined to have a serial number in a range including his plane.
Topics: Australia, News, World News, Aliens, UFO