Pure speculation:
Possible explosive decompression @ FL350 .... followed by intentional emergency descent ..... without quick-donning O2 mask or no oxygen flow. Result - partial lack of conciousness (or temp complete loss) and spatial disorientation leading to unintentional descent to below level of surrounding terrain. Probable cause: mechnical failure combined with pilot error.
There's not much fuselage volume in a Lear Jet. If it blows and one of you don't get the mask on instantly .... things can get more than interesting very quickly. It's my guess that in most cases private/corporate pilots (at least one of them) don't actually wear the mask at high altitude.
Thought: Most celebrities know nothing about flying. When they charter a jet, especially an older/cheap one, they don't necessarily get what they expect.
Last edited by surplus1; 11th Dec 2012 at 22:55.