Chapter 3 - Using the Analytical Approach to Investigate Accidents

What is analysis, and how can it be used in accident investigations? Analysis is a systematic and exhaustive process used to determine what is unknown about an accident by examining all of the known facts or circumstances surrounding it. As a result of an accident analysis, the analyst will know as much as possible about what caused the accident and will be able to recommend corrective actions.

In taking an analytical approach to accident investigation, the investigator interviews people involved with the accident, takes photographs, and uses other investigative techniques to analyze an accident. In this fact-gathering process, the investigator develops scenarios that help to reveal what happened before and during the accident. This is the accident sequence. The events in the accident sequence that are deemed to have been causes or significant factors are called the causal factors.

The Phases of an Accident Investigation

from the accident if the investigation is not thorough, and it is difficult to determine corrective actions if the accident sequence and causal factors have not been identified. Unfortunately, the investigative phase seems to be left out of many “investigations,” which makes it difficult if not impossible to conduct a proper analysis of the accident.

Many safety professionals compare accident investigation to the problem-solving process. As in that process, the accident investigator defines a problem, gathers data, analyzes the facts, and determines and evaluates solutions (Handley 2000).

The analytical approach establishes consistency in and lends validity to the accident investigation process. Training in analytical techniques also helps investigators to determine how much they need to find out about an accident and how much interviewing and data collection are necessary.

Thinking Analytically

During an accident investigation, it is necessary to break down the events surrounding the accident into workable pieces and dissect each one to determine whether it is significant. This requires structured thinking, a process that does not come naturally to everyone. Studying the techniques described in Part III of this book will help you to structure your thought processes and learn to systematically break down an accident.

An accident investigator must use a structured process to develop the accident sequence and a systematic and exhaustive approach to analyze evidence and determine causal factors. The analytical phase of accident investigation starts with discovering facts about the accident and using them to determine the accident sequence, and from the sequence deriving the causal factors. This systematic process eventually enables the investigator to determine corrective actions that will not only prevent recurrence of the accident, but also prevent other accidents in the future.

Root Causes and Root Cause Analysis

Safety professionals disagree about how many “root causes” there should be in an accident and even about what a root cause is. Root cause analysis is more of a process than an investigative tool or analytical tool.

Levels of Root Causes

Safety professionals agree that it is important to uncover the root causes of an accident, but everyone in the safety profession seems to have a different view about what constitutes a root cause and at what levels root causes exist. Suppose, for example, that while a worker is hammering, the hammer head comes loose, flies off the handle, and hits another worker. One investigator might say that the root cause of this accident was at the worker level. Another might examine the same accident and find that the hammer broke because proper tool maintenance procedures were not followed, so the root cause was at the management level. There are many levels of accountability, from the worker level to supervisory, management, and even corporate or program development levels. The philosophy of this book is that accident investigators must analyze events at all levels to determine the causes of the accident as well as recommend corrective actions.

Some safety professionals distinguish between “root causes” and “direct causes.” In the hammer example above, the direct cause is an engineering failure—the hammer came apart. The root cause is what allowed the engineering failure to take place—in this case, management’s failure to make sure tool inspections were being carried out. In the same example, an investigator might have identified another direct cause—worker failure—if the worker was using the hammer to do something it was not intended to do. In this case the root cause would be supervisory failure if the supervisor failed to notice that the worker was using the hammer improperly. This book discusses all of an accident’s causal factors and corrective actions that may be taken at every level.

The Many Meanings of “Root Cause”

One problem with using the root cause concept is that the term “root cause” has many meanings among safety professionals. It may be defined as the first cause of an accident, the last cause of an accident, the cause that if corrected would have prevented an accident, the cause that involves management systems, the cause that started the accident sequence, or the cause that would have prevented the accident if it had not happened. These various definitions reduce the effectiveness of the term “root cause.” Some companies even have a list of possible root causes and designate one of them as the root cause of each accident. Some people call this “dial-a-cause.” It allows safety professionals to make excellent charts and graphs for studying trends, but the accident itself tends to disappear while the root cause becomes the emphasis of the investigation. Many of the root causes in such a system boil down to either human error or management system failure, and it is difficult to recommend corrective actions based on such broad categories. This superficial approach obviously prevents a systematic and exhaustive process of discovering the causes of an accident. Our employees are worth more effort than this.

Ranking Root Causes

Some companies rank the root causes identified during an investigation in order of importance. This writer believes that corrective actions can be prioritized, but that causes should not be ranked.