Abstract: Employee #1, working for True Drilling LLC in Wamsutter, WY, was part of a crew that was tripping pipe into a drill hole. Employee #1 ascended a derrick wearing his personal fall arrest system. Employee #1 was attempting to grip a stand of pipe but was having difficulty. After several failed attempts to secure grip of the stand of pipe, with the aid of an air tugger to align the stand towards him at one point, Employee #1 was seen leaning forward at an acute angle with his feet on the derrick platform and his hands on or near the pipe stand. At this time, Employee #1 was heard yelling for assistance and, moments later, fell from his position on the derrick. Employee #1 was killed. At the time of the fall, his positioning system waist belt was unbuckled and he was not connected to the derrick via any type of personal fall arrest system.