Conducting an Accident Investigation
Course 102
Safety Certified Supervisor Series

MODULE 5: DETERMINING SURFACE AND ROOT CAUSES

Time to analyze for cause

Three levels of cause analysis

As mentioned earlier in the course, accidents are processes that culminate in an injury or illness. An accident may be the result of many factors (simultaneous, interconnected, crosslinked events) that have interacted in some dynamic way. In an effective accident investigation, the investigator will conduct three levels of cause analysis:

Injury analysis. At this level of analysis, we do not attempt to determine what caused the accident, but rather we focus on trying to determine how harmful energy transfer caused the injury. Remember, the outcome of the accident process is an injury.

Event Analysis. Here we determine the surface cause(s) for the accident: Those hazardous conditions and unsafe behaviors described throughout all events that dynamically interact to produce the injury. All hazardous conditions and unsafe behaviors are clues pointing to possible system weaknesses. This level of investigation is also called "special cause" analysis because the analyst can point to a specific thing or behavior.

Systems analysis. At this level we're analyzing the root causes contributing to the accident. We can usually trace surface causes to inadequate safety policies, programs, plans, processes, or procedures. Root causes always pre-exist surface causes and may function through poor component design to allow, promote, encourage, or even require systems that result in hazardous conditions and unsafe behaviors. This level of investigation is also called "common cause" analysis because we point to a system component that may contribute to common conditions and behaviors throughout the company.