Abstract: At 11:15 a.m. on February 6, 2017, Employee #1, a crew leader, and Coworker #1, a helper, both employed by a heating and air conditioning company, were working at a warehouse. They were assigned to finish an equipment installation job by replacing two roof HVAC units. The bottom half of the fixed ladder to the roof was blocked by a metal storage rack measuring about 9 feet 8 inches in height. Employee #1 used a rolling staircase and climbed its seven steps to the landing platform. He then climbed over the metal guardrails and onto the top shelf of the metal storage rack. Coworker #1, who was standing on the rolling staircase, handed Employee #1 a compressed gas cylinder containing nitrogen that Employee #1 planned to use to leak-test the HVAC units. The gas cylinder weighed approximately 35 pounds and measured about 19 inches in height. As Employee #1 shifted to the fixed ladder and began to climb with the gas tank in one hand. Near the top of the ladder, he fell, hit the storage rack, continued falling and landed on the concrete floor, a fall height of approximately 17 feet. Emergency services were called, and Employee #1 was transported to the hospital. He was admitted and treated for a transverse fracture of his lower back (lumbar).