Abstract: SEAGRAVE AERIAL LADDER TRUCK (MODEL #PA-20766) RESPONDED TO A FIRE CALL. THE DRIVER PARKED WHERE INSTRUCTED AND BEGAN SETTING UP THE TRUCK. SINCE THE TRUCK WAS PARKED ON LEVEL PAVEMENT THE DRIVER DIDN'T BOTHER PUTTING OUT THE JACK PADS WHEN EXTENDING THE JACKS, NOR DID HE CHOCK THE TRUCK'S WHEELS. HE SET UP THE HOSE AND LADDER BY ATTACHING THE HOSE TO THE END OF THE LADDER THE BEST WAY POSSIBLE, SINCE THE LOCK NUT FOR THE HOSE NOZZLE AT THE END OF THE LADDER WOULDN'T WORK. THE LADDER WAS RAISED TO A 35 DEGREE ANGLE AND EXTENDED TO A LENGTH OF 100 FEET. WHEN WATER PRESSURE WAS APPLIED TO THE HOSE EMPLOYEE #1 CLIMBED THE LADDER TO THE END. HE ATTACHED THE SAFETY BELT HE WAS WEARING AND PROCEEDED TO GUIDE THE WATER HOSE. THE DRIVER AND ANOTHER FIREFIGHTER WERE PREPARING TO RELIEVE EMPLOYEE #1 AND PROVIDE STRAPS TO SECURE THE WATER HOSE. SUDDENLY THEY SAW THE LADDER TURN TO THE LEFT, SWAY, AND BREAK AT THE INTERSECTION OF THE FIRST AND SECOND EXTENSIONS. EMPLOYEE #1 RODE THE LADDER DOWN APPROXIMATELY 50 FEET AND SUSTAINED INJURIES TO HIS HEAD, LEGS, CHEST, ARMS AND PELVIS. CAUSAL FACTORS INCLUDE THE FAILURE TO LOCK THE EXTENSIONS IN PLACE AND FAILURE TO FOLLOW THE MANUFACTURER'S RECOMMENDATIONS AND INSTRUCTIONS FOR SETTING UP THE TRUCK AND LADDER. ALSO, THE ANGLE OF OPERATION WAS NOT SUFFICIENT FOR CLIMBING AND THE LADDER WAS OVEREXTENDED.