I'm trying to get my pilots license and this is my theory, as well as many other pilots theories. There are two types of flying VFR (visual flight rules) and IFR (insturment flight rules) IFR means you can soully fly by being dependent on your insturments. He didn't have his IFR rating and was flying around and the weather got foggy and he wasn't able to get IFR clearance because he didn't have his rating. Thats MHO, they said he was site seeing and flying at 1000ft which is pretty low and maybe he accidentaly pitched the plane down, I'm not sure but RIP...and prayers to the family