Early in the flight, the aircraft, which was climbing to its assigned altitude on autopilot, lost cabin pressure, and all six on board were incapacitated by hypoxia, a lack of oxygen in the brain and body.

The plane ran out of fuel over South Dakota and crashed into a field near Aberdeen after an uncontrolled descent, killing all six on board.

The four passengers on board were PGA golfer Payne Stewart; his agent, and former Alabama football quarterback, Robert Fraley;[4][5] president of the Leader Enterprises sports management agency, Van Ardan; and Bruce Borland, a golf architect with the Jack Nicklaus golf course design company.

At about 15:12 UTC, Olson concluded his inspection of N47BA and broke formation, proceeding to Scott Air Force Base in southwestern Illinois.

[2] Officials at the Pentagon denied that a shoot down of the Learjet was considered to prevent a possible crash in a heavily populated area, indicating that the fighter jets were not armed with air-to-air missiles.

He writes in his 2018 memoirs, "The plane was heading toward the city of Winnipeg and the air traffic controllers feared that it would crash into the Manitoba capital.

"[2] Impact occurred approximately 17:13 UTC, or 12:13 local, after a total flight time of 3 hours, 54 minutes, with the aircraft hitting the ground at nearly supersonic speed and at an extreme angle.

[2] The first officer, 27-year-old Stephanie Bellegarrigue, held a commercial pilot certificate and type ratings for Learjet and Cessna Citation 500.

No definitive evidence exists that indicates the rate at which the accident flight lost its cabin pressure; therefore, the Safety Board evaluated conditions of both rapid and gradual depressurization.

If there had been a breach in the fuselage (even a small one that could not be visually detected by the in-flight observers) or a seal failure, the cabin could have depressurized gradually, rapidly, or even explosively.

A more gradual decompression could have resulted from other possible causes, such as a smaller leak in the pressure vessel or a closed flow control valve.

Safety Board testing determined that a closed flow control valve would cause complete depressurization to the airplane's flight altitude over a period of several minutes.

Investigations of other accidents in which flight crews attempted to diagnose a pressurization problem or initiate emergency pressurization instead of immediately donning oxygen masks following a cabin altitude alert have revealed that, even with a relatively gradual rate of depressurization, pilots have rapidly lost cognitive or motor abilities to effectively troubleshoot the problem or don their masks shortly thereafter.

In this accident, the flight crew's failure to obtain supplemental oxygen in time to avoid incapacitation could be explained by a delay in donning oxygen masks; of only a few seconds in the case of an explosive or rapid decompression, or a slightly longer delay in the case of a gradual decompression.

In summary, the Safety Board was unable to determine why the flight crew could not, or did not, receive supplemental oxygen in sufficient time and/or adequate concentration to avoid hypoxia and incapacitation.

[2] The NTSB report showed that the plane had several instances of maintenance work related to cabin pressure in the months leading up to the crash.

Stewart was ultimately headed to Houston for the 1999 Tour Championship but planned a stop in Dallas for discussions with the athletic department of his alma mater, Southern Methodist University, about building a new home course for the school's golf program.

On June 8, 2005, a Florida state court jury in Orlando found that Learjet was not liable for the deaths of Stewart and his agents.