We have over a dozen Apprentices in our club. When we first got the "S" models, they were crashing. The pilot would just lose all response and they would nose dive into the ground.

What we discovered was the folks that were crashing were not allowing the plane to initialize properly. They would move the plane as it was initializing. Also, ... as a precaution, once there is a rough landing or a lot of handling of the plane, then we set it on the ground and reinitialize. We have not lost one since, and that was about a year ago that we had our last crash! Also, I suspect significant wind motion during initialization could cause a similar problem.