This is tragic but also a headscratcher. In all my 39 years of flying I have never heard of such an event. And with an instructor on board, hard to fathom.
Buckle up folks!
http://www.foxnews.com/us/2013/03/30...ll-from-plane/
Addendum: Another more recent report says he was not a student but in fact an experienced pilot who was being checked out in the plane he had recently purchased.