Pilot went missing moments after reporting UFO following him to air traffic controllers

Decades after his disappearance, the final minutes of pilot Frederick Valentich still fascinate people.

20-year-old Valentich had been flying from King Island off Australia's south coast to Moorabbin, located south west of Melbourne, when he sent out a strange transmission to the airport traffic control tower.

The Australian pilot claimed that there was a mysterious aircraft flying above him 'playing some sort of game'.

Shortly after his final conversation with the tower, Valentich vanished.

Following his disappearance, there have been many theories about what may have happened to the young pilot.

Among them, of course, are conspiracy theorists who believe that Valentich had been abducted by aliens.

But what really happened on that night in 1978?

Frederick Valentich disappeared in 1978. (Australian Department of Transportation)

Valentich had been hoping to become a full-time pilot, but found himself rejected from both the Australian Air Force and commercial training.

It also wasn't his first incident, with Valentich having received warnings on previous occasions.

The 20-year-old had planned to mark an anniversary with his girlfriend on October 21, 1978.

The evening before Valentich informed her that he was going on a flight to King Island and they planned to meet when he returned.

He took off in a Cessna 182L light aircraft in the evening.

"It is hovering and it's not an aircraft"

While flying over the ocean Valentich reported to ground control that he was being followed by another aircraft, but they confirmed that there was not another aircraft in his vicinity.

He claimed that there were four bright 'landing lights' circling above him.

Speaking with the tower, Valentich 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.

A Cessna light aircraft similar to the one Valentich was flying. (Arpingstone / Wiki)

"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."

Finally, he added: "That strange aircraft is hovering on top of me again. It is hovering and it's not an aircraft."

What really happened to Valentich?

There are a number of theories as to what may have happened to the pilot.

One was that Valentich became disoriented in the dark and had been flying upside down, with the lights actually being his own lights reflected in the sea.

However, this explanation was dismissed as his aircraft used a gravity fed fuel system, so couldn't sustain flying upside down 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 plane 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'.

In some cases, a 'graveyard spin' 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 failed to find the pilot, but in 1983 a fragment of aircraft bearing a serial number in the range of Valentich's was discovered.