"It is hovering and it is not an aircraft."
These are the last words anyone ever heard Frederick Valentich say before his radio cut off and he, and the aircraft he was piloting, were never seen again.
On October 21, 1978, a 20-year-old Valentich rented a single engine plane out of Victoria's Moorabbin Airport with plans of heading to Tasmania's King Island to catch seafood.
But things took a terrifying turn when he noticed he was being followed by another aircraft.
It has been 40 years since the young Aussie pilot disappeared over the Bass Strait and in that time no one has come any closer to finding out what happened to him.
The only clue left behind was a radio conversation between him and Melbourne Airflight Service Controller, Steve Robey.
It was 7pm when Valentich radioed in to ask if there were any known aircraft in the area, just after something zoomed overhead.
Robey informed him that there was "no known traffic" in the area and inquired as to what type of plane it was.
"I cannot affirm. It is four bright, it seems to me, like landing lights. The aircraft has just passed over me at least a thousand feet above," Valentich said.
As the transmission went on things got even more unnerving, with Valentich reporting that the mystery aircraft was "playing" with him.
"It seems to me that he's playing some sort of game," he said.
"He's flying over me two, three times, at a time at speeds I could not identify."
The conversation continues with the controller trying to get more information about what the object actually is.
Valentich describes it as long, metallic and with a green light.
At one point the aircraft vanishes before suddenly reappearing on his other side.
It's at this point that Valentich says his final, terrifying words: "It is hovering and it is not an aircraft."
There is silence for 17 seconds before the transmission abruptly cuts off.
An extensive search was conducted of the water and any surrounding land but Valentich nor any indication of a crash site was ever found.
The incident gained worldwide attention and sparked many conspiracy theories, with the most popular being that Valentich was abducted by a UFO.
Others concluded that he faked his own death or was flying upside down and the lights he saw were actually his own reflecting on the water before he crashed.
After the story came out there were contradicting reports about why the inexperienced pilot was heading to the island.
He had told his father that he was heading out to catch crayfish but later told flight officials that he was picking up some friends.
But even more questions were raised about Valentich's intentions when it was revealed that he had not informed King Island airport of his intention to land.
In a disturbing coincidence it was also discovered that Valentich was obsessed with UFO's and had watched numerous movies and collected articles on the topic.
A week after he vanished the young pilot's dad, Guido, told reporters that he was sure his son was still alive and was adamant that he had been taken by the UFO.
"All I am worried about is that he was released in a different area, very far away from where he was taken," he told reporters.
All that remains now of Frederick Valentich's infamous flight is a plaque at Otway lighthouse commemorating his strange disappearance.