WINDMILLING - THE ANATOMY OF A TOWER CATASTROPHE By Robert F. Gonsett Copyright, Communications General Corporation, 1999 This article describes the step-by-step events that led to the tower collapse which claimed the life of Andy Figge, a well respected rigger and Registered Professional Civil Engineer. The article was written at the request of several Southern California broadcast engineers who had close ties with Andy and wanted to understand the events that cost him his life. Hopefully, this understanding will help others avoid similar tragedies. Most of the technical information in this article was obtained from Ernie Jones, a Registered Professional Mechanical and Civil Engineer. Ernie visited the accident scene as a good neighbor and pieced together the events from interviews and physical evidence. Additional data were provided by Ralph Young, president of Empire Crane Service, and Hundley Batts, one of the owners of the broadcast station where the tragedy occurred. A small amount of non-technical information was gleaned from a Huntsville Times article of February 12, 1999. Here, then, is how the tragedy appears to have unfolded: On February 10, 1999, Andy Figge was in the process of installing a 250 foot guyed uniform cross-section tower at Radio Station WEUP(AM), Huntsville, Alabama. He had erected the first 100' of tower and had attached three fiberglass guy lines to the top of that tower. The remaining 150 feet of tower was laying on the ground in a continuous length where it had been preassembled out of 10 foot sections. The plan was to use a crane to set the 150 footer on top of the existing 100 footer, and that would be done in two stages. The first stage involved connecting a crane cable to the side of the 150 footer so there was about 60 feet of tower on one side of the connection point and 90 feet on the other. The 150 foot section was successfully lifted upright and temporarily set parallel against the existing 100 foot tower section with the bottoms of both sections essentially at ground level. (The base of the 100 foot section was anchored to its "point type" foundation while the bottom of the 150 footer was resting firmly on the ground.) Since the crane was not tall enough to lift the 150 footer into place with the crane cable attached at the 90 foot mark, Andy reconnected the cable to a point that was only 70 feet above ground. That left 80 feet of tower above the connection point and caused an obviously unstable situation where the tower could "windmill" and turn over. Andy had anticipated that state of affairs and had already attached weights to the bottom of the 150 foot section to prevent overturning. In the second stage of the project, Andy was atop the 100 foot tower section and secured to the tower with his climbing belt. He was ready to bolt the bottom of the 150 footer to the top of the 100 footer as soon as the crane completed the lift. A decision was made to raise the 150 foot section, just a little, to make sure that the added weights were sufficient to prevent windmilling. Unfortunately, the weights were not sufficient. The bottom of the 150 foot tower section moved out horizontally at an alarming rate (the crane cable attachment point serving as the pivot) and the bottom of the 150 footer headed directly for the studio/transmitter building. The crane operator reportedly tried to set the load down, but could not do so in time. Seconds later, the bottom of the 150' tower section slammed into the underside of the roof eave. That brought the rotation of the 70 foot portion to a halt. Of course, the 80 foot portion wanted to keep going. This state of affairs put tremendous strain on what we could now call the "top" tower leg of the 150 foot section. A leg bolt broke (calculations suggest that its ultimate strength was exceeded) so that the 150 foot section folded in two with the 80 foot end eventually coming to rest on one of the fiberglass guy wires that held Andy's 100 foot tower section upright. The guy line reportedly held at first, then broke as the tower metal slid down and sheared or sliced the line. Andy was never able to unbuckle himself and rode the 100 footer down as it toppled onto the roof of the studio/transmitter building. He was reportedly killed instantly. There were no other injuries or fatalities associated with the accident. Ralph Young, president of Empire Crane Service, commented that a safety meeting had been held on Monday prior to the job, and that the crane operator had attended. Andy presented himself professionally and there was no question in anyone's mind that he had carefully thought over each step of the job, and that he was well qualified to complete it. Through the course of this project, the staff and management of Empire Crane and WEUP had grown to respect and care about Andy as an individual. They were severely shaken by the tragedy. Empire Crane had reportedly been in business 34 years without a major injury accident. By clearly understanding the step-by-step events that led to the fatality, it is hoped that similar accidents will be prevented. ______ This article is published as part of the CGC Communicator newsletter and may be reprinted or republished - free of charge - provided the story is unaltered and printed in full, including this section. Stories that pertain to this incident begin with CGC Newsletter #312.