Abstract: STURCTURE #696 HAD BEEN ERECTED AND A CREW WAS AT THE STRUCTURE SITE FOR CLEANUP WORK CONSISTING OF RE-CHECKING TO MAKE SURE ALL BOLTS WERE IN PLACE AND TIGHT ALONG WITH POLICING THE GROUND AREA. THEY HAD BEEN FLOWN IN BY HELICOPTER TO BE ASSIGNED VARIOUS TASKS AND LOCATIONS. EMPLOYEE #1 ALONG WITH THREE OTHER EMPLOYEES HAD CLIMED THE LADDER,LOCATED ON THE SOUTH WEST LEG,AND WERE MOVING ABOUT THE STRUCTURE, IN MOVING ABOUT IT WAS,ON OCCASSION,NECESSARY TO UNHOOK THE SAFETY LINE THEN RE-HOOK INTO THE D-RING AT THE NEW WORK POSITION. THEY WERE WORKING APPROXIMATELY 80 FEET ABOVE THE GROUND LIVEL. EMPLOYEE #1 WAS APPARENTLY IN THE PROCESS OF HOOKING HIS SAFETY LINE ONTO HIS BODY BELT D-RING. OTHER EMPLOYEES STATED THEY HAD HEARD A CLICK-LIKENED UNTO THE NOISE MADE WHEN THE SAFETY LINE IS SNUGGED ON THE D-RING. APPARENTLY #1 HEARD THE CLICK ALSO AND ASSUMED THAT THE SAFETY LINE WAS PROPERLY HOOKED INTO THE D-RING, LEANED BACK AND SINCE THEY PROPER HOOK UP HAD NOT BEEN MADE, FELL TO THE GROUND. IT WAS STATED THAT #1 WAS CARRYING IN THE RIGHT SIDE TOOS PUNCH-AN OPEN END WRENCH 12" LONG AND A PIN OF CHANNEL LOCK PLIERS WHICH WOULD HAVE PROTRUDED OUT OF THE POUCH SOME 6" AS WOULD THE WRENCH HAVE DONE. IDENTIFY THE TYPE CLOTHING WORN BY#1 AT THE TIME OF FALL THINKING THERE COULD HAVE BEEN SOME OBSTRUCTION FROM WHICH THAT COULD HAVE PREVENTED PROPER HOOKING OF THE SAFETY LINE INTO THE D-RING, APPARENTLY THIS WAS NOT THE CASE #1 WAS WEARING A SHORT LEVIJACKET AND ACCORDING TO OTHER EMPLOYEES THE D-RINGS WERE FULLY EXPOSED.