On July 2, 1998, a 37-year-old male equipment operator (the victim) was crushed in the cab of a track-mounted hydraulic excavator (Backhoe) when a brick chimney toppled over and struck the machine during demolition operations. The victim and a co-worker, a truck driver, were in the final stages of demolishing a 2 1/2-story stone and stone veneer house. They had demolished about 75 percent of the structure, leaving a large brick chimney between 26 and 30 feet high and part of a stone wall. As the victim proceeded to knock down the rest of the wall, the co-worker seated inside the truck saw the chimney sway and topple en masse, falling directly across the operator's cab of the machine. The weight of the chimney crushed the cab with the victim inside. NIOSH investigators concluded that to prevent similar incidents in the future, employers should: ensure that before demolishing and structure, and engineering survey is performed by a competent person to determine the condition of the structure, evaluate the possibility of unplanned collapse, and plan for potential hazards and injuries; ensure that machine operators are provided with the safest work environment possible by complying with the boom height standards of ANSI A10.6-1990 Safety Requirements for Demolition Operations.