Maintenance Q&As

What are the most common sources of human error in maintenance?

Answered July 19 2019

Some of the typical causes of human error are poor training, poor management, poorly written operating or maintenance procedures, and improper work tools. There are three general types – skill-based, rule-based, and knowledge-based errors. By determining the type of error, you can narrow down the potential sources and more easily identify where you have room for improvement.

A majority of failures and accidents in maintenance are caused by some element of human error. In the aviation industry, for example, an estimated 80 percent of maintenance errors involve human factors.

Familiarizing ourselves with each type of error will help us catch them in real-world settings. By spotting these scenarios early on, we can better plan out strategies to prevent future incidents.


Skill-based errors surprisingly occur most often while doing routine activities. Repetitive tasks that might have previously been performed many times without issues are still susceptible to this type of error. As workers become more familiar with routine activities, there is a tendency to perform tasks with less conscious attention. This might seem counter-intuitive, but experienced workers are in fact more prone to committing skill-based errors than less experienced workers.


Maintenance work usually has detailed procedures and instructions to guide technicians as they complete tasks. The “rules” here are those guidelines – set to ensure the safety and quality of the work performed. Rule-based mistakes occur when the misuse or disregard of certain rules results in a negative outcome. This type of error can further be broken down into two subtypes:

1) Misapplying a good rule

This error type occurs when a rule is used in an inappropriate situation. It’s a good rule, but since it’s not relevant to the scenario at hand, an error results.

2) Applying a bad rule

Applying a bad rule occurs when teams or facilities develop informal rules. Bad habits or cutting corners may get the job done, but when these practices become common, they’re often seen as informal rules. If these bad rules turn into routine processes, unwanted consequences will follow.


Knowledge-based errors usually occur when workers perform tasks for the first time. Mistakes of this nature happen due to insufficient knowledge of the activity at hand. These errors come from ‘trial and error’ and a lack of procedural knowledge. They are somewhat unavoidable when new people are added or new failures come up, but if repeated over time they can indicate a breakdown in processes.

Managing human error in maintenance

Research studies show that more than 50% of equipment fail prematurely after being serviced. While human error is inevitable, the incentive to manage and prevent it as much as possible is huge. To minimize human errors in maintenance, you must first recognize the different error types, then grow aware of their root causes, and finally develop a plan of action to prevent them from happening again.

Take human errors as a specific area for improvement. Investing in proper training, for example, can help reduce human errors significantly. In one study, a training program specifically designed to reduce human error resulted in a 50% reduction in incidents within the first year, proving that though human error is inevitable to an extent, it is certainly manageable.

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