Abstract: At 9:30 p.m. on March 4, 2019, an employee, a Derrick Hand, was rigging up a jackknife production rig at an oil well site. As the employee was rigging up one of the derrick board support lines, it became caught behind the guide horn on the derrick. Once the line was observed to be in the wrong position, the employee was assigned to climb the derrick to move the line out from behind the horn. The employee climbed the derrick and attached a winch line to the derrick board. His coworker activated the winch to lift the derrick board and achieve some slack on the stuck line. As the employee guided the trapped line out from behind the horn, the support line suddenly tightened up trapping the employee's left pinky finger between the support line and the outside edge of the horn, resulting in the amputation of the tip of his finger. The employee was not hospitalized.