WHILE EMPLOYEE WAS STANDING ON THE TOP STEP OF CAT OF THE MOUNTING LADDER, AFTER COMPLETED CONVERSATION WITH THE OPERATOR, THE OPERATOR NOTICED THE EMPLOYEE HAD GONE ASHEN AND HIS EYES WERE BEGINING TO ROLL BACK AND NO RESPONSE, HE BEGAN TO FALL OFF THE LADDER AND THE OPERATOR WAS UNABLE TO KEEP HOLD OF HIM. HE FELL DOWN THE SIDE AND HIT GROUND WITH LEFT SHOULDER.