I was recently reading up on the 1981 Hyatt Regency walkway collapse. It was a tragic loss of life and haunts many to this day.
The linked article does a better job of summarizing things, but here's a summarized version of what led up to the collapse:
The engineering firm (Gillum & Associates) designed the walkways to be supported on really long, threaded rods. The company supplying the rods (Havens Steel) didn't like the specified rods because they were going to be expensive and likely to be damaged during construction. Havens Steel sent an alternate design to Gillum & Associates which was used for the construction.
The alternate design didn't meet code, catastrophically failed, and led to the loss of many lives.
The Missouri Board of Architects, Professional Engineers, and Land Surveyors found Gillum & Associates guilty of negligence and revoked all of the engineering licenses assigned to Gillum & Associates and its employees.
What I'd like to understand better is why Gillum & Associates was held liable for the disaster. Wasn't it really Havens Steel's fault for proposing the alternate design to begin with? If Havens Steel had built according to the original design proposed by Gillum & Associates, then the disaster never would have occurred.