Abstract: Employee #1, of Crysen Refining, was collecting a sample of catalyst from inside a MDDW Reactor. Wearing an air supplied respirator with an escape bottle, he entered through an 18 in. opening at the top of the reactor and used a chain ladder to descend 13 ft to the top of the catalyst bed. He then had to go through a tray 78 in. from the opening. A coworker serving as a hole watch told Employee #1 to come out to change his air supply cylinder, but witnesses say that it appeared that the employee did not hear him. His air supply became critically low and coworkers yelled at him to hurry. Employee #1 started to come out, but was said to be moving very slowly. When he got onto the tray, he fell over. The hole watch ran over to the supply cylinder to check the pressure, and then ran back, during which time a coworker (a welder) had gone into the vessel without a breathing apparatus. The welder tried to lift Employee #1 to the opening. Two other coworkers grabbed the employee's arm and tried to pull him out, at which time the welder went down. The coworkers were partially overcome by a lack of oxygen and had to let go. One of the coworkers stated that he could hear what sounded like air leaking and noticed that the employee's air hose was disconnected. An attempt was made to rescue Employee #1, but coworkers could not get through the top opening with a SCBA. Employee #1 died of asphyxia. Neither of the employees that went into the vessel was wearing a harness or lifeline.