Abstract: At approximately 5:35 p.m. on December 31, 2009, Employee #1 was found dead at the bottom of a vertical reciprocating conveyor (PFlow Industries, Inc., Mechanical Vertical Lift/Series M) shaft. The conveyor was located in the East Plant Processing Blend Tower, bunker 9. Employees were using the reciprocating conveyor to move equipment and trash cans. Employee #1 and a coworker placed two trash cans onto the conveyor and sent it down to the first floor to be emptied. The coworker then walked down the stairs to empty the trash cans. After emptying the trash cans, the coworker called Employee #1 and stated that he was sending the trash cans back up to the fourth floor. Employee #1 responded that he would remove the trash cans from the conveyor. Employee #1, thinking that the conveyor car was at the fourth floor level, opened the door to the conveyor, but failed to notice that the car was not present. He fell into an empty shaft. The gates to the conveyor were supposed to be interlocked with the lift operation so that they could not be opened without the car being present. An investigation revealed that the interlock failed and the doors on the fourth floor opened without the car being present.