I was just looking at the NTSB Preliminary Accident Report on the Cherokee accident that claimed the lives of the Oklahoma State women's basketball coach and three others. One thing that puzzled me was, "Radar data showed the airplane level at 7,000 feet mean sea level on a southeasterly heading." Why was an experienced CFI flying at an IFR altitude while operating as a VFR flight? "Visual meteorological conditions prevailed for the flight, which operated without a flight plan." The accident occurred in Arkansas, so the plane was more than 3,000 feet above the surface.
I image that we'll never know, since there frequently isn't enough data in these kind of accidents to reach a probable cause, but it has me wondering.