A tank overflowed, resulting in a spill to the environment. The operator filling the tank was using the wrong revision of the procedure, which had an incorrect calibration chart for the tank.

A mechanic doing maintenance in a confined space was not allowed to take a written procedure with him. As a result, he had to review the procedure and commit it to memory. During performance of the task, he omitted an important step. This resulted in the failure of a key piece of equipment.

An operator made a mistake performing a calculation. The data used in the calculation came from multiple steps in the procedure. He made a mistake in transferring one of the data points from an earlier step in the procedure to the step at which the calculation was performed.