Root Cause Analysis "The Five Whys"
Updated: Apr 27
“Five Why” analysis is a systematic approach used to identify the causal factors and root cause of incidents such as injuries and near misses.
Consider this example. A company I once worked with consistently experienced slips and falls on a walkway between two warehouses during winter months. Snow and ice would continually build up on the warehouse roofs. When temperatures increased the snow and ice would melt causing water to collect on the walkway where it eventually turned to ice. They initially addressed this issue by applying ice melt on the walkway. As the incidents continued, the company decided that it was time to implement a new analysis technique. They decided to use “Five Why” analysis.
5 Whys Accident Investigation Example
The first step in “Five Why” analysis involves defining the problem. In this case, the problem involved employees slipping and falling on ice between the warehouses.
After defining the problem, the analysis team asked the question “why is that” in succession to identify the root cause and causal factors involved with the problem:
1st Why (is that)? - Why are employees slipping on ice between the warehouses?
Answer: Water from snow and ice melt on the roofs is collecting on the walkway between the warehouses.
2nd Why (is that)? – Why is water from snow and ice melt collecting on the walkway between the warehouses?
Answer: The gutters on both warehouses are not effectively carrying the water to nearby drains.
3rd Why (is that)? – Why are the gutters not effectively carrying water to the nearby drains?
Answer: The gutters are leaking.
4th Why (is that)? – Why are the gutters leaking water?
Answer: The gutters are deteriorated and have never been cleaned, repaired, or replaced since installation over 40 years ago.
5th Why (is that)? – Why haven’t the gutters been cleaned, repaired, or replaced since installation?
Answer: There is no maintenance requirement for cleaning, inspection, or repair.
The fifth “why” is referred to as the corrective action level of why, also known as the root cause. When conducting a five whys accident analysis, identify the root cause. Then, develop an action plan to address the problem. The analysis team in this example worked to identify all potential means to eliminate, reduce, or control the hazard prior to deciding on the most feasible option. The identified corrective action involved replacing the steel gutters with aluminum gutters that are less likely to deteriorate. An annual inspection and gutter cleaning were also added to the facility’s preventative maintenance program. In the short term, pedestrian traffic was diverted from the area until the new gutters were installed.
As you can see, the corrective action was much more effective than just applying de-icer to the area. “Five Why” analysis has its limitations, but in the absence of another analysis tool, it can be a good place to start.
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Joe Mlynek is a partner and subject matter expert at Safety Made Simple, Inc. He has over 20 years of experience in safety at the corporate level and as a consultant. He is a Certified Safety Professional (CSP) and Occupational Safety and Health Technician (OHST). Joe can be reached at firstname.lastname@example.org