Abstract: At 9:15 a.m. on August 27, 2015, Employee #1 and his supervisor had been assigned to clean out concrete silo #507, that measured 30 feet in diameter and held a 50/50 mix of soybeans and corn. There were 500-1,000 bushels of grain left in the silo when the two workers entered. A third employee had conducted air monitoring prior to the supervisor completing an entry permit. Employee#1 and the supervisor reviewed the results and put on fall protection harnesses and lanyards, and locked out the overhead fill conveyors prior to entry. They were using a JLG Model # 860SJ aerial lift to gain access to the 24 inch x 24 inch entry point on the north side of the concrete silo, 20 feet above ground level. Employee #1 entered through the opening which was 4 feet down and at a 60 degree slope to the south where the sump was located. Employee #1 attached a 50 foot lifeline to the top rail of the aerial lift basket and then to his harness prior to entering the silo. Employee #1 then walked the grain down to the sump, in view of the supervisor. The third employee was in the conveyor basement operating the sump gate, in radio communication with the supervisor. While Employee #1 was cleaning the bin, the grain came down the 60 degree slope, engulfing him underneath of 4 feet of the mixed grain. The supervisor radioed for help. Other employees arrived and 911 was called. Several volunteer fire and rescue departments arrived and assisted in the rescue, using multiple grain engulfment rescue panels. Ninety minutes after the 911 call came in, Employee #1 was found. The grain had asphyxiated and killed him.