On December 29 1980, fifty-one-year-old Betty, who lived in Dayton Texas and ran a grocery store and restaurant, was out for the day with a friend, Vickie Landrum aged fifty-seven and Vickie's grandson, Colby, aged seven. They had driven in Betty's Oldsmobile Cutlass to find a bingo game, but the halls were closed in preparation for New Year parties. Instead they had a meal in New Carey and began their journey home to Dayton. It was around nine o'clock and Betty was driving along Highway FM1485 through this swampy area, where Lake Houston and its various tributaries run south to Galveston Bay. It was chilly and the car windows were closed and the heater on. The night sky was clear after a day of intermittent rain. There was a three-quarter moon and the area was bright from the streetlights of Houston, thirty miles away.

Colby saw it first- a bright, glowing object racing them above the tops of the oaks and pines that edged the road. It seemed to be about three miles ahead of them. It grew larger and seemed to be making for the road ahead of them. Betty's instint was to outrun it, but the Oldsmobile wasn't fast enough. She was forced to brake hard as the object came in and hovered infront of them, about 25ft off the ground, straddling the highway. In descriptions the three witnesses gave, it was, in Vickie's phrase, 'like a diamond of fire'. It seemed to be made of aluminium, and the four points of the diamond were rounded. It had a row of blue lights across the centre and emitted bleeps from time to time.

Vickie, a commited Christian, genuinely believed that this was the Day of Judgement and cradled a terrified Colby in her arms as the object rose and fell slightly on downblasts of flame ahead of them. Betty got out of the car. She stood in front of the bonnet, as though mesmerised by the light, apparently unaware of the intense heat the object was giving off. Vickie and Colby sceamed at her to get back inside, but when she tried, the door handle was too hot to hold and she had to use the leather sleeve of her jacket to open it. No sooner had Betty got back into the car than a swarm of helicopters - they counted twenty-three in the next few minutes - arrived from nowhere and moved off again, along with the glowing craft.

Betty drove on and all three of them were still able to see the diamond, glowing in the sky about five miles away, its light illuminating the helicopter escort. They were not the only witnesses. An oil worker in Dayton saw the UFO - "It was kind of diamond-shaped and had two twin torches that were shooting brilliant blue flames out the back." A bakery clerk in Eastgate, eight miles west of Dayton, reported a bright light in the sky over New Carey. An off-duty Dayton policeman and his wife saw the helicopters, as did an inhabitant of Crosby. They flew right over his house.

For Betty, Vickie and Colby the physical symptoms began almost at once. When Betty dropped the Landrums at their home that night, Vickie complained of a headache and sickness. Over the next few days, grandmother and grandson showed sighns of acute sunburn. They vomited and suffered from diarrhoea which lasted for days. Vickie lost 30% of her hair; Colby too lost hair, but much less. Both had pain in their eyes and their sight deteriorated. Vickie still fears she will eventually go completely blind and worries for Colby, who, doctors told her, could develop leukaemia if the problem is radiation sickness, as suspected.

Betty fared worse. She had blinding headaches and felt she was going to die. Huge blisters appeard on her skin, so disfiguring that friends who called to see her in hospital could not recognise her. She developed an aversion to anything hot - the sun, even warm water. A month later she had lost over 50% of her hair and suffered from a continuous eruption of skin conditions.

The encounter left its mark emotionally, too. Both women, previously bright and vivacious, are now withdrawn and nervous. Both have been in and out of hospital and neither has been able to work again.

Neither Betty Cash nor the Landrums could be shaken on their testimony. Of the helicopters they saw; some were large, double-rotor CH-47 Chinooks, which have an unmistakable 'telephone' shape in the air; others were smaller, single-rotor types of the Bell Huey variety. Other witnesses agreed that what they had seen with the UFO were Chinooks. Betty and Vickie sued the United States government for physical and emotional damage and loss of earnings, but the case failed after representatives of the US Army, Navy and Air Force, and from NASA, testified that they neither owned nor operated any such craft. But ufologists have pointed out that there are other agencies who weren't in court that day, and who gave no such assurances. The army base at Fort Hood near Killeen didn't know of anybody who could put that number of helicopters in the air. The Houston Intercontinental Airport Federation Aviation Administration said that nearly 400 helicopters operated commercially in the Houston area, but not one of them was a Chinook.