We had a very serious crash today testing XBee/joystick-level control where the vehicle lost all attitude control--the vehicle just pitched/rolled gradually, lost LOS, and eventually crashed (3 broken booms, 1 motor). We are running a sparkfun Explorer board and Digimesh 900. We were using the 'channels_override' action, mainly putting the copter in loiter via our own software client (AND this wa…