Why Track Close Calls?
In 1986 the Space-Shuttle Challenger exploded soon after lift-off due to faulty o-rings. Engineers working on the shuttle had, previous to the accident, noted that that some of the o-rings used in other shuttle missions were degrading. Management had been informed the night before the launch of Challenger for the potential for such failure.
Was previous reporting of the o-ring degradation a Close Call?
A Close Call is defined as an unplanned sequence of events that could have caused harm if conditions were different or are allowed to progress, but did not in this instance.
In hindsight, this disaster may have been prevented.
Why track Close Calls? The behaviors and conditions that lead to actual accidents and injuries are the same as those involved in Close Calls. If we can get an idea of what almost happened, we can help prevent accidents and injuries that do happen. This is a much cheaper method of prophylaxis (both in terms of human and financial costs).
In 1931, H.W. Heinrich reported on a study of accidents that he classified according to severity. Heinrich's report showed that for each serious-injury incident, we could expect about 29 minor injuries and 300 Close Call or property-damage incidents, as represented in the above diagram.
A category that should be added to the base of this safety-pyramid is "Unsafe/Hazardous Conditions and Behaviors." This is what fuels the other events in the pyramid.
If we decide to track Close Calls, what do we do with the information?
1. Investigate the Close Call and find out what happened, what could have happened and why.
If we can take these steps, and encourage our employees to report Close Calls without the fear of reprisal, the work environment will improve, employees will feel empowered to participate in their safety and we will have a safer workplace.
More information about Close Calls is available at the ES&H website.