Abstract: At 12:00 p.m. on December 26, 2018, Employee #1, a machine operator, was unjamming a Wachter Packautomatik stacking unit machine. The machine is surrounded by a cage with three access point doors. Each door has a key that allows an operator to activate the machine by turning the key to the on position or render the machine inoperable by taking the key away from the key hole. Employee #1 used a key to enter the caged area and left his key at the access door. While Employee #1 was troubleshooting the machine, a coworker, who was in training, went through another access point door, leaving the key at the door. The coworker left the area and actioned the machine from the access door while Employee #1 had his left hand and forearm in the point of operation of the flipper stacker portion of the machine. Employee #1 sustained a serious crushing injury to his left arm that included multiple fractures and nerve damage that was repaired with a surgery. He was hospitalized for multiple days.