ABCNEWS.com reports on the Payne Stewart tragedy. RealVideo (download RealPlayer)

Sixth Victim Possible
Late today, there were unconfirmed reports that there may be a sixth victim. Jack Nicklaus said he feared one of his golf course designers, Bruce Borland, 40, also died in the crash. Borland was flying to Texas because he wanted to design a course with Stewart under the Nicklaus Design banner, Nicklaus said.
     Borland’s wife, Kate, said she contacted the private jet terminal this afternoon and spoke to an employee who had greeted her husband and confirmed he intended to board the flight.
     Officials at the crash site said they could not tell exactly how many people had been killed.

Plane Fell Into Field
Eyewitnesses say the plane fell straight down into the field, South Dakota Gov. Bill Janklow told ABCNEWS.com from the crash site about 12 miles west of Aberdeen. No one on the ground was hurt.

The plane crashed in Mina, S.D. It had taken off from Orlando, Fla., headed for Dallas. (ABCNEWS.com/ Magellan Geographix)

Hunters in an adjacent field watched it fall, as did state highway patrol officers who watched the plane with binoculars as it descended from the clear sky from about 20,000 feet, Janklow said. The jet’s impact blew a sizable crater in the earth, he said, and left the hole full of debris.
     “It’s a huge, devastating scene,” Janklow said. “You can imagine what it did to the airplane and the human beings on the airplane.”
     Investigators will find little to work with at the scene, Janklow said.
     “Very few pieces of this tragedy are larger than a couple square inches,” said Janklow, who was told about the runaway jet about 40 minutes before the crash.

Possible Depressurization
Two F-16 fighter planes had been following the jet looking for signs of distress. Federal officials said it appeared to be flying on auto pilot before the crash.
     The Learjet 35 left Orlando this morning at about 9:09 ET and lost radio contact about a half hour later, officials said. It was scheduled to land in Dallas.
     The last communication officials had was that the plane was over Gainesville, Fla.
     FAA spokesman Paul Turk said the plane had flown as high as 45,000 feet and the crew did not respond to repeated inquiries from air traffic controllers.
     “What is the most likely probability here is that this aircraft, which has a very small cabin compared to a commercial jetliner, lost cabin pressure some time during the climb out of Orlando,” said ABCNEWS aviation analyst John Nance.
     He said that at altitudes above 30,000 feet, a pilot would have to strap on an oxygen mask quickly or his mind would become so muddled from lack of oxygen — a condition called hypoxia — that he could no longer help himself.
     “The time of useful consciousness at 25,000 feet is a fairly sedate 20 to 25 minutes. But the time of useful consciousness at 39,000 feet is six to 12 seconds, ” said Nance.
     “The fact that this aircraft continued climbing right through their assigned altitude on up to almost 45,000 feet, without any call from the pilots, indicated to me that this crisis occurred some place before 39,000 but most probably above 30,000.”
     The Air Force reported the plane had been “porpoising,” its altitude fluctuating between 22,000 and 51,000 feet.

Stewart’s Wife Tried to Call Him
As the Lear 35 eerily raced across a half a dozen states, Stewart’s Australian-born wife Tracey, following the drama on television, tried to reach her husband on his cellular phone, according to her brother.
     “She was trying to ring him on his mobile and couldn’t raise him,” Mike Ferguson, a professional golfer, told the Australian Broadcasting Corp. radio. “It’s just really bad for my sister to be watching it on CNN, knowing that it was her husband on board.”

Military Aircraft Tracked Jet
According to an Air Force summary, after contact was initially lost, two F-15s from Tyndall Air Force Base, Fla., were sent to track the Learjet. The F-15s pulled back and two F-16s in the air from Eglin Air Force Base, Fla., moved in to track the aircraft.
     After the Learjet reached the Midwest, the Eglin F-16s pulled off and four F-16s and a midair refueling tanker from the Tulsa National Guard followed it.
     Eventually, two F-16s from Fargo, N.D., moved in close to look into the windows to see if the pilot was slumped over and to help clear air space. Officials hoped that the F-16s could provide assistance to anyone on board who might have helped land the plane safely.
     The pilots drew close and noticed no structural damage but were unable to see into the Learjet because its windows were frosted over, indicating the temperature inside was well below freezing.
     The F-16 pilots said they saw the plane, apparently out of fuel, fall to the ground.