Undaunted, at 7.45pm local time the next day, Hill again held his breath as TAM 5 climbed rapidly, turning gracefully before disappearing out of sight on a 62-degree heading towards Ireland. By 11pm, satellite data showed the tiny aircraft still aloft at a satisfactory altitude, making approximately 43mph with no tailwind.

At 8.30 the following morning, the little plane, nicknamed The Spirit of Butts Farm, after the farm in Maryland owned by Beecher Butts where it had been tested, was roughly 560 miles out. But Hill noted some ominous data from satellites monitoring its telemetry.

The aircraft's four-stroke engine was supposed to be regulated at 3,900rpm, but the readings ranged from 3,100 to 4,100rpm. The plane's altitude was bouncing between 280 and 320 metres, suggesting a porpoising flight path from a shallow climb to a speedy dip.

"The Spirit trotted along all day Sunday," Hill reported. "Over the mid-ocean it picked up a 5-10mph tailwind and was cruising at 50-55mph. I went to bed at roughly 10pm, fearful that the cool of night would increase the viscosity of the fuel, taking the engine from lean to dead."

When he awoke at 4am, there had been no satellite data for three hours, and Hill believed the plane was lost; it was agreed to stand down the officials in Ireland who were making a special six-hour trip from Dublin to the landing site at Mannin Beach, Co Galway.

But just then, data from one of the satellites confirmed that TAM 5 was not only still flying, but was now far enough east to be in warming sunshine, and had shed a lot of fuel weight. By 9am local time (12.30pm in Ireland), the Spirit was a mere 70 miles from the Irish coast.

The landing was a cliffhanger. The engine had been set to run for roughly 37 hours, and Hill worried it might stop a couple of miles short of the landing site.

At 2pm Irish time, the Spirit of Butts Farm hove into view at Mannin Beach, and one of the Irish officials took manual control, banging the rudder stick hard right to kill the engine. A mobile phone link was opened to Hill as the Spirit made a dead-stick landing approximately five feet from the designated spot. At 2.08pm, hearing over the phone link the shout "It's on the ground!", Hill led a whooping cheer, buried his head in his wife's shoulder "and wept unashamedly for joy".

The plane's tank contained less than two ounces of fuel – a quarter of a cupful. "In the model airplane world, this is no different from Armstrong landing on the moon," Carl Layden, an official observer of the feat, announced.