Abstract: At 10:45 a.m. on January 9, 2023, an employee and coworkers, steel erectors, were performing structural steel erection operations of a 1,000,000 square foot warehouse building. The scope of the work included the installation of metal decking on the roof which consisted of welding 22 Gauge, Type B, 3-foot wide by 18-foot long metal decking panels. For fall protection, the workers were utilizing full body harnesses with self-retractable lifelines attached to roof anchors. The installation process consisted of dividing 12 workers in groups of two to handle the panels. Ten workers were positioning the panels while two employees were tack-welding the panels in place. The employee was assigned to tack weld the panels in place during. After approximately 20 panels were secured to the roof, most of the workers came down to the ground however four workers remained on the roof, including the employee. The employee, for unknown reasons, was not wearing his harness when he fell approximately 45 feet from the roof to the concrete floor below and died instantly as result of the impact.