Chris Gibson, an oil drill engineer, told Jane's he saw the aircraft from the rig Galveston Key in August 1989. A trained member of the Royal Observer Corps, he said that it was apparently refuelling from a KC-135 tanker and was escorted by two F- 111 bombers. Although high, it was clearly visible against high cloud.
He did not take his sketch to the media at the time, as he was still a member of the ROC, a home-defence organisation funded by the Home Office. The ROC was abolished on 30 September last year. Santa Fe Drilling, which owns the Galveston Key, an offshore drilling unit, says it was hired to Amoco at the time and would have been south of the 54th parallel, in the UK sector of the southern North Sea. This is further south than previous reports linked with the Aurora.
Mr Gibson took his sketch to Bill Sweetman, author of the article in Jane's, who said Aurora would travel at eight times the speed of sound - 5,280 mph. This would enable it to reach any point on the earth's surface in three hours.
The name Aurora derives from an unexplained line in the 1984 US defence budget next to the SR-71 Blackbird. The Pentagon retired the SR-71 early in 1990, saying it would rely on satellites, but satellite orbits are predictable.
Experts believe the US has developed a successor to the SR-71, shrouded in the secrecy of its 'black budget', and that the aircraft may be flying across the Atlantic. A Scottish air traffic controller has picked up something travelling at three times the speed of sound and people living near Machrihanish, Argyll, a Nato reserve airfield have complained of a 'pulsating, ear- splitting shriek'. That is the sound associated with a hybrid rocket-ramjet engine suitable for a 'hypersonic' plane - one that goes at more than five times the speed of sound.
In California, the US Geological Survey picked up several sonic booms over southern Nevada in late 1991 and earlier this year. They were made by something travelling at several times the speed of sound - and not the Space Shuttle.
Mr Gibson's sketch indicates an aircraft in the form of a 75 degree swept triangle and the right shape for a 'lifting body aircraft' - in which the body itself provides lift. A hypersonic plane goes so fast it does not need conventional wings. Up to a certain speed it is rocket-powered, but then a ramjet, using the air ingested at great speed, takes over.
The article says the aircraft appears to be up to 27 m (81 ft) long.