HE WAS DRIVING A TRACTOR-TRAILER BEWLLY-DUMP COAL TRUCK DOWN A 6% RAMP. TRUCK HIT A SLICK SPOT, AND TRAILER BEGAN TO SKID. WHEN OPERATOR TRIED TO CORRECT, THE TRUCK HIT A BERM, AND THE DRIVER' S HEAD HIT THE WINDOW. HIS GLASSES CUT HIS CHEEK--THE CUT REQUIRED 2 STITCHES. THE OPERATOR WAS WEARING HIS SEAT BELT.