Every job has with it a critical step.  A step that is so important that if it is not done correctly and accurately will result in serious and significant harm to the individual (or others in the vicinity) or to the equipment / asset involved.  The harm could be a life-threatening, life-altering, or life-ending event or significant damage to the equipment and production unreliability.  As part of the pre-job planning and tool-box talk the identification of these critical steps is highly important so that everyone’s focus and attention can be in the right place as these steps are started and begun and as these steps are approached that the readiness to continue can be checked and verified.  Before strtign a critical step, it is a good point to hold the team and review the preparaations to continue.  Asking yourself and the team questions about their readiness and the status of pre-conditions necessary to proceed are all part of the final checks to proceed to this critical step.  By definition a critical step is not reversible, so once it occurs it cannot be undone (like the ringing of a bell) so takign the time necessary to prove readiness prior to initiation is a key activity.