A garbled message told of another aircraft in the area. Eight seconds later, co-pilot Paul Heffernan was heard to report "12 000 ft descending, spinning rapidly." The plane was seen to level out some 1000ft (330m) above the sea before crashing.

Speculation about Flight 712's demise have been rife for over three decades; and is again newsworthy thanks to recently uncovered, allegedly authentic documentation. A book is also available by Dermot Walsh: Tragedy at Tuskar Rock (Mercier Press, 1983)

Conspiracy theories abound. Originally sparked off by the conclusion of official investigator Richard O'Sullivan that "there was another aircraft involved is inescapable. No aircraft have been reported missing, but there remained the possibility that an unmarked aircraft, either a drone aircraft target or a missile, might have been there."

The most popular theory concerns a missile launched from the Royal Aircraft Establishment's testing range in Aberporth, Wales. The British Ministry of Defence (MoD) states that what was then Britain's top missile development center was closed on Sundays. Recently, Radio Telifis Eireann (Ireland's state broadcaster) found inconsistencies in log books, suggesting that the center was open for business. Another theory is that a radar transponder on board the Viscount failed; a British warship, HMS Penelope thought it was a pilotless drone. The MoD claims that none of its ships were close enough, but the log books of two of the five ships in the area are missing: the other three were never requested by the Irish government. Yet another theory tells of a pilotless drone hitting Flight 712: some witnesses reported seeing an aircraft with red wings close to the Viscount's last position.

In the late 1960s the Royal Air Force used de-commissioned Meteor jets for target practice. The remains of one were pulled out of the sea near Tuskar Rock in 1974. Wexford fishermen have ridiculed RAF claims that the wreckage "floated there." The currents and tides in the area suggest otherwise.

The litany of inconsistencies, cock-ups, claims and 'lost files' continue:

Although several witness reports pinpointed the exact location of the crash, the Royal Navy could not find it, even after seventy days. Local trawlerman Billy Bates, on his first visit to the search area, found it immediately, exactly where the Royal Navy said they had already looked three times. When the HMS Reclaim crew lifted the fuselage without a steel net, it fragmented on the surface, sunk to the bottom again, along with bodies, ruining any chance of discovering the cause.

On RTE's Questions & Answers program (18 January 1999), Minister for Public Enterprise, Ms O'Rourke announced that while she had requested that 'Aer Lingus' furnish her department with the official report on the matter, she was told that such a report did not, and never did exist.

The official British Ministry of Transport file was shredded four years ago. A two-page CIA document, recently 'uncovered' under the Freedom of Information Act by a US investigator working for Ms. Bonnie Gangelhoff (whose parents died in the crash) claims that HMS Penelope was conducting missile tests with the new Seadart missile, one of which hit the Viscount. The document claims that bodies were cremated by the British authorities to cover up evidence that the plane was hit by a missile.

The British Embassy called the document "gruesome and possibly libellous" and that, "It doesn't even look authentic. The language is wrong, one or two of the names of people in charge of the investigation are correct but others are wrong, and the ship which is supposed to have done this wasn't in range and did not carry any missiles."

The views expressed above represent the writer and not necessarily those of The Disinformation Company Ltd.