That was the flight with golfer Payne Stewart, I believe.
You are correct.
On October 25, 1999, a month after the American team rallied to win the 1999 Ryder Cup in Brookline, Massachusetts, and four months after his U.S. Open victory at Pinehurst No. 2, Stewart was killed in the depressurization of a Learjet flying from Orlando, Florida, to Dallas, Texas, for the year-ending tournament, The Tour Championship, held at Champions Golf Club in Houston that year. Traveling on a Monday morning, Stewart was planning to stop off in Dallas to discuss building a new home-course for the SMU golf program.[24] The last communication received from the pilots was at 9:27 AM EDT, and the plane made a right turn at 9:30 AM EDT that was probably the result of human input. At 9:33 AM EDT the pilots did not respond to a call to change radio frequencies, and there was no further contact from the plane. The plane was, apparently, still on autopilot and angled off-course, as observed by several U.S. Air Force (and Air National Guard) F-16 fighter aircraft[25] as it continued its flight over the southern and midwestern United States. The military pilots observed frost or condensation on the windshield (consistent with loss of cabin pressure) which obscured the cockpit, and no motion was visible through the small patch of windshield that was clear.
National Transportation Safety Board investigators later concluded that the plane suffered a loss of cabin pressure and that all on board died of hypoxia. A delay of only a few seconds in donning oxygen masks, coupled with cognitive and motor skill impairment, could have been enough to result in the pilots' incapacitation. The NTSB report showed that the plane had several instances of maintenance work related to cabin pressure in the months leading up to the accident. The NTSB was unable to determine whether they stemmed from a common problem – replacements and repairs were documented, but not the pilot discrepancy reports that prompted them or the frequency of such reports. The report gently chides Sunjet Aviation for the possibility that this would have made the problem harder to identify, track and resolve; as well as the fact that in at least one instance the plane was flown with an unauthorized maintenance deferral for cabin pressure problems.
According to a USAF timeline, a series of military planes provided an emergency escort to the stricken Lear, beginning with an F-16 from Eglin Air Force Base, about an hour and twenty minutes (9:33 EDT to 9:52 CDT – see NTSB report on the crash) after ground controllers lost contact. The plane continued flying until it ran out of fuel and crashed into a field near Mina, South Dakota, a town ten miles (16 km) west of Aberdeen, after an uncontrolled descent. The five other people aboard the plane included Stewart's agents Robert Fraley and Van Ardan, and pilots Michael Kling and Stephanie Bellegarrigue, along with Bruce Borland, a highly regarded golf course architect with the Jack Nicklaus design company.