EE WAS OPERATING A ROOF BOLTER AT THE TIME OF THIS INCIDENT. HE STATED THAT HE HAD SWUNG THE BOLTER BOOM OUT TO PUT UP THE RIB PIN AND AS HE POSITIONED HIMSELF TO INSTALL THE BOLT HE SLIPPED O N SOME LOOSE BOTTOM LOST HIS BALANCE AND STARTED TO FALL BACKWARDS. AS HE FELL HE GRABBED THE BOOM CONTROL JOY STICK TO STEADY HIMSELF. HIS LEFTFOOT SLID UNDER THE BOLTER BOOM & BOOM LOWERED.