MINA, S.D. - A Learjet carrying champion golfer Payne Stewart and at least four other people flew a ghostly journey halfway across the country Monday, its windows iced over and its occupants apparently incapacitated, before spiraling nose first into a grassy field. Everyone aboard was killed.
The flight plan said two crewmembers and three passengers were on the jet, but there were reports a sixth person boarded the plane just before it took off from Orlando, Fla.
The chartered, twin-engine Lear 35 may have suddenly lost cabin pressure soon after taking off for Dallas, government officials said. Air traffic controllers couldn't raise anyone by radio.
Fighter jets were sent after the plane and followed it for much of its flight but were unable to help. 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.
Set apparently on autopilot, the plane cruised 1,400 miles straight up the nation's midsection, across half a dozen states. Authorities say the plane was ''porpoising,'' fluctuating between 22,000 and 51,000 feet. It presumably ran out of fuel some four hours after it took off.
''The plane had pretty much nosed straight into the ground,'' said Lesley Braun, who lives two miles from the South Dakota crash site.
Stewart, 42, was one of the most recognizable players in golf because he wore traditional knickers and a tam-o'-shanter hat. He won 18 tournaments, including three major championships. In June, he won his second U.S. Open, prevailing over Phil Mickelson with an astonishing 15-foot putt on the last hole.
''This is a tremendous loss for the entire golfing community and all of sports. He will always be remembered as a very special competitor and one who contributed enormously to the positive image of professional golf,'' PGA Tour Commissioner Tim Finchem said.
President Clinton said: ''I am profoundly sorry for the loss of Payne Stewart, who has had such a remarkable career and impact on his sport and a remarkable resurgence in the last couple of years.''
Stewart was on his way to Texas, first for a meeting on a proposed golf course near Dallas, then on to the Tour Championship in Houston for the top 30 on the PGA Tour's money list. He attended Southern Methodist University in Dallas and had friends in the area.
Also killed were Stewart's agents, Robert Fraley and Van Ardan, and the two pilots, identified as Michael Kling, 43, and Stephanie Bellegarrigue, 27. The jet was operated by Sunjet Aviation Inc.
Jack Nicklaus said Monday that he feared one of his golf course designers, Bruce Borland, 40, also died in the crash.
Borland's wife, Kate, said she contacted the private jet terminal Monday afternoon and spoke to an employee who had greeted her husband and confirmed he intended to board the flight.
Authorities could not confirm that Borland was aboard and officials at the crash site said they could not tell exactly how many people had been killed.
''I am truly shocked and saddened,'' Nicklaus said in the statement released by Nicklaus Design. ''Our hearts go out to their families, as well as the families of the other victims in the accident.''
Six National Transportation Safety Board investigators walked through the crash site Monday night. They did a cursory inspection of the wreckage, lit by generator-powered spotlights. Bob Francis, NTSB vice chairman, declined to comment and said the investigators would be back Tuesday morning.
Planes that fly above 12,000 feet are pressurized, because the air at altitudes above that is too thin to breathe. If a plane loses pressure, those aboard could slowly lose consciousness or, if an aircraft broke a door or window seal, perish in seconds from lack of oxygen.
Once reaching a cruising altitude, pilots often switch on the autopilot. If they pass out, the plane could continue on until it ran out of fuel.
Gov. Bill Janklow, who was at the crash site, said it appeared Stewart's Learjet ran out of fuel because there was no fire. He said the plane and the bodies were obliterated.
Instances in which a civilian jet lost pressure in flight are extremely rare.
However, the Stewart crash was similar to an accident nearly 20 years ago that took the life of Louisiana State University football coach Bo Rein. Rein left Shreveport, La., in 1980 in a private plane en route to Baton Rouge. Radio contact with the pilot was lost, and the plane flew off course for hundreds of miles before going down in the Atlantic off Virginia. Investigators think the plane may have lost pressure.
The last communication from Stewart's jet was over Gainesville, Fla., said Tony Molinaro, an FAA spokesman in Chicago. The jet flew as high as 45,000 feet and the crew did not respond to repeated inquiries from air traffic controllers, the FAA said.
A government source said the plane should have turned left at Gainesville on a course for Dallas. It made only a partial turn before heading in a straight line toward South Dakota.
The FAA routed air traffic around the Learjet and kept planes from flying underneath it in case it crashed.
Fighter jets from Florida and Oklahoma went after the plane. Two F-16s had to make several passes to align with the plane, which was flying steady in the clear blue sky but was going slowly in comparison with the fighter jets.
Air Force Capt. Chris Hamilton said there was nothing he could do when his F-16 caught up with the Learjet over Memphis, Tenn.
''It's a very helpless feeling to pull up alongside another aircraft and realize the people inside that aircraft potentially are unconscious or in some other way incapacitated,'' Hamilton said. ''And there's nothing I can do physically from my aircraft - even though I'm 50 to 100 feet away - to help them at all.''
Pentagon spokesman Kenneth Bacon said the military never considered shooting down the Learjet.
The Rev. Jim Henry, retired pastor for First Baptist Church of Orlando who used to minister to the Stewart family, was one of those outside the Stewart home after the crash.
''He was a wonderful Christian who had Christ in his life and somehow in his death,'' Henry said. ''That brought a great sense of peace to his family in a difficult and tragic time.''
Stewart and his wife, Tracey, had two children, Chelsea, 13, and Aaron, 10.
