Three Primary Phases Of Accident Investigation Cause Analysis

Three Primary Phases Of Accident Investigation Cause Analysis

Conduct Cause Analysis

You’ve completed the initial step of the accident analysis by gathering information and using it to break the accident down into an accurate sequence of events. You have a good mental picture of what happened. Now it’s time to continue the analysis process by completing each of the following three phases of analysis to determine what caused those events.

Tree phases of analysis:

  • Phase 1: Injury Analysis: It’s important to understand, we’re not analyzing the accident in this phase: we are analyzing precisely what happened during the accident event to identify the type of harmful energy involved (electrical, mechanical, thermal, etc.) and how the harmful transfer of this energy (an action) caused the injury or illness. Remember, the outcome of the accident process is an injury or illness.
  • Phase 2: Surface Cause Analysis: In this next phase in the analysis process, you determine how the hazardous conditions and unsafe behaviors described in each of the events interact to produce the accident. The hazardous conditions and unsafe behaviors uncovered are the surface causes for the accident and give clues that point to possible system weaknesses.
  • Phase 3: Root Cause Analysis: During this phase of the analysis process, you’re analyzing the weaknesses in the Safety Management System (SMS) that contributed to the accident. You can usually uncover weaknesses related 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.
Conduct Cause Analysis

Phase 1: Injury Analysis

It’s important to understand all injuries to workers are caused by one thing: the harmful transfer of energy. Let’s take a look at some examples that illustrate this important principle.

  • If a harsh acid splashes on your face, you may suffer a chemical burn because your skin has been exposed to a chemical form of energy that destroys tissue. In this instance, the direct cause of the injury is a harmful chemical reaction. The related surface causes might be the acidic nature of the chemical (condition) and working without proper face protection (unsafe behavior).
  • If your workload is too strenuous, force requirements on your body may cause a muscle strain. Here, the direct cause of injury is a harmful level of kinetic energy (energy resulting from motion), causing injury to muscle tissue. A related surface cause of the accident might be fatigue (hazardous condition) or improper lifting techniques (unsafe behavior).

The important point to remember here is the “direct cause” of the injury is not the same as the “surface cause” of the accident event.

  • The direct cause of injury is the harmful transfer of energy as a consequence of your exposure to that energy. The direct result of the harmful energy transfer is injury. The cause is the harmful transfer of energy. The effect is the injury.
  • The surface cause of the accident is the condition and behavior that interacts in a way that results in the harmful transfer of energy. The interaction of the condition and behavior is the cause. The effect is the harmful transfer of energy.

Phase 2: Surface Cause Analysis

You learned that each event in our sequence will include an actor and an action that may have contributed to the accident. Once we have identified the actors and actions in the sequence of steps, our next job is to analyze each event to determine the surface causes for the accident.

What are Surface Causes?

The surface causes of accidents are those hazardous conditions and unsafe or inappropriate behaviors within the sequence of events that have directly caused or contributed in some way to the accident. It’s important to understand that surface causes describe unique conditions or individual behaviors.

hazardous condition is characterized by the following:

  • a unique tool, piece of equipment, or machinery, etc., that is not properly guarded or somehow defective
  • an employee’s “state of being” such as fatigue or being distracted
  • may also be a unique defect in a process, procedure or practice
  • may exist at any level of the organization
  • is the result of deeper root causes

Unsafe or Inappropriate Behaviors are characterized by:

  • taking an intentional/unintentional action that is unsafe or failure to take an action that is safe
  • a unique performance error in a process, procedure or practice
  • may exist at any level of the organization
  • are the result of deeper root causes

It’s important to know most hazardous conditions in the workplace are the result of the unsafe or inappropriate behaviors that produced them.

The Seven Steps of a Thorough Incident Investigation

Phase 3: Root Cause Analysis

The root causes for accidents are the underlying SMS weaknesses that consist of thousands of variables, any number of which can somehow contribute to the surface causes of accidents. This level of investigation is also called “common cause” analysis (in quality terms) because you’re identifying a system component that may contribute to common conditions and behaviors that exist or occur throughout the company. These weaknesses can take two forms.

  • SMS Design Root Causes: Inadequate design of one or more components of the safety management system. The design of safety management system policies, plans, programs, processes, procedures and practices is very important to make sure appropriate conditions, activities, behaviors, and practices occur consistently throughout the workplace. Design root causes describe the “condition” of the SMS, and ultimately, they contribute to most accidents.
  • SMS Performance Root Causes: Inadequate implementation of one or more components of the SMS. After each SMS component is designed, it must be effectively carried out or implemented. Performance root causes describe the “behavior” of the SMS. You may design an effective safety plan, yet suffer failure because it wasn’t implemented properly. On the other hand, if you effectively implement a poorly designed component, you’ll get the same results: inadequate system performance.

Ultimately, for the SMS to be effective, both the design and implementation must be effective.

Assume the SMS Failed

When conducting an accident investigation, a basic assumption should be that somehow the SMS has failed. The investigation will either verify this assumption or prove it wrong. Most of the time, it will be verified. Why is that? Most accidents in the workplace result from unsafe work behaviors.

  • unsafe behaviors are the primary surface cause for the vast majority of all workplace accidents;
  • hazardous conditions are the primary surface cause for a small percentage of workplace accidents; and
  • uncontrollable (unknowable) “acts of God” account for the remaining very small percentage.

These statistics imply that, because SMS weaknesses contribute in some way to workplace hazardous conditions and unsafe behaviors, those weaknesses are ultimately responsible for almost all workplace accidents. So, the basic assumption should be that, ultimately, most accidents are the result of SMS weaknesses, not unsafe behaviors or hazardous conditions.

To effectively fulfill your responsibilities as an accident investigator, you must not close the investigation until these root causes and solutions have been identified.


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