A Learjet 35 flying from Orlando, Florida to Dalls Love Field, Texas crashed in South Dakota.
For undetermined reasons the plane lost its cabin pressurization during flight. As the altitude warning alarm was raised, the crew failed to perform the complete emergency checklist for a loss of cabin pressurization because they did not apply the oxygen masks immediately.
Payne Stewart, two time winner of the Golf US Open, was on board of this flight. All crew member and passengers were killed. This plane crash was featured on Season 16 Episode 1 of "Mayday".
Links: en.wikipedia.org, aviation-safety.net, www.planecrashinfo.com