David Fravor from Toledo, Ohio, was flying a F/A-18F super hornet off the coast of San Diego while the US Navy tracked mysterious UFOs for two weeks in November 2004.

It was before a bizarre encounter with one of the objects that was later investigated by a multi-million dollar top secret government program looking at mysterious aerial threats.

Details of the Department of Defense Advanced Aerospace Threat Identification £16.5million secretive programme investigating the threat posed by UFOs, and Mr Fravor's case, were revealed last month.

Cmdr Fravor and Lt Cmdr Jim Slaight were two pilots each in an F/A-18F super hornet on a routine training mission 100 miles out over the Pacific Ocean off the coast of San Diego when it happened.

They were with the USS Princeton guided missile cruiser and SS Nimitz supercarrier at the time.

Mr Fravor said it was at the end of a two-week period when the Princeton had been tracking mysterious "Tic Tac-shaped" aircraft that appeared suddenly at 80,000 feet, before shooting down towards the ocean.

They stopped at 20,000 feet and appeared to hover, before dropping off range or heading back upwards.

Speaking to Bostonglobe.com about the implications of the case, known as the Nimitz UFO, Mr Fravor said:“I think the story needs to be told. We need to stop making jokes and start paying attention to it.