Abstract: On or about August 16, 1991, five employees were rigging up a Spencer Harris Model 5000 trailer-mounted oil well drilling rig at a new location. The sub-base was set and then the pony sub was placed on top of the sub-base; it was leveled by eyesight only. The trailer-mounted rig was backed onto the pony sub and preparations were made to raise the derrick while two of the three screwjacks on the pony sub were partially braced under the trailer. The fully extended derrick was raised before the turnbuckles from the trailer were attached to the sub-base to provide stability. The trailer was also not leveled. After the derrick was raised, apparently Employee #1 fell from the rig and died.