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Human Factors, Human Error & The Role of Bad Luck in Incident Investigations


As an Organisational Psychologist working with clients in various safety critical industries over the past 25 years I often get asked for some advice on how to better manage the 'human factor' within an organisation. Usually the conversation begins with a frustrated question from a senior manager that goes something like this. "We have all these mature systems and procedures in place and a low Total Recordable Injury Frequency Rate (TRIFR) but it is the 'idiot factor' that we can't seem to stop. How do we stop people doing stupid things". Of course herein lies part of the problem - using the terms 'stupid' or 'idiot' will do little to help.

This article will outline how we can improve the quality of workplace health and safety investigations by better understanding the role of human factors. A better understanding will ultimately provide insight into practical error management strategies designed to tolerate the errors that individuals will ultimately make.

Human Error is an action or inaction

To better understand the human factors contribution to workplace incidents and accidents, we first need to determine what the outcome of poor human factors is; and that is human error. Often the terms human error and human factors are used interchangeable - but they are quite different things.

Human error is a generic term that involves all those instances where a planned activity fails to achieve its intended outcome. For example, forgetting to set your park brake in your car or misapplying your vehicle brakes in wet and slippery road conditions.

The best non academic definition of human error comes from my former PhD supervisor Professor James Reason who often remarked that saying that an individual makes errors are about as useful as breathing oxygen or implying it was bad luck. In other words errors are quite normal. To make this point I ask the participants in my training courses if they remember the movie Meet Joe Black. You know the movie with Brad Pitt who plays the part of the devil who has come to take the life of the business mogul played by Anthony Hopkins? There is a scene in the movie where Pitts character reminds people that there are two certain things in life - death and taxes. What Mr Pitt forgot was the third most certain thing in life - human error. So human error does not really involve idiots then unless we all admit to being idiots!

So just how normal is human error? In fact, research suggests that regardless of the activity or task being conducted, humans make between 3-6 errors per hour. One study in aviation maintenance conducted by my former Australian Transport Safety Bureau (ATSB) colleague Dr Alan Hobbs, found that aviation maintenance engineers made on average 50 observable errors per work shift. The good news is that most of the time, these errors are self-corrected and they have little consequence.

The following represents a summary of agreed views about human error from experts on the subject:

  • Errors do not usually occur randomly - there are generally reasons for them.

  • An active hazard must be present for errors to become consequential - not paying attention when working at height is more of a problem that not paying attention when watching a movie.

  • Even a relatively small error can trigger a very serious accident, if the system is vulnerable and has poor defences or risk controls.

  • Human error knows no boundaries. Regardless of experience level, professionalism, gender or national culture - everybody makes errors. However, the silver lining is that experts at particular tasks are often better than novices at anticipating errors, and taking action to prevent them becoming serious.

Saying that an individual made an error is about as useful as saying it was an Act of God. Human error needs to be explained and one way to start is to understand that human errors are not all the same; they can be divided into either unintentional or intentional actions.

  • Unintentional actions—those in which the right intention or plan is incorrectly carried out, or where there is a failure to carry out an action. These actions typically occur due to attention or memory failures.

  • Intentional actions—those actions that involve conscious choices. These actions are largely due to poor judgment or motivational processes.

The diagram below illustrates the difference between unintentional and intentional actions which is covered in the Incident Cause Analysis Method (ICAM) training session on human error.

Types of Human Error

Poor Human Factors can lead to Human Error

So if human error is what an individual or team commits ‘actively’ (someone did or didn’t do something); then human factors are the reasons why the errors occur!

Human factors is an umbrella term for the study of people’s performance in a specific environment. Within the workplace, human factors is about the relationship between people and the equipment they operate, their environment, the information and knowledge available to them, and importantly, their interactions with other people.

Simply put human factors can be thought of as conditions that if not managed correctly can lead to human error. For example, a condition like fatigue can lead to poor decision making (mistake).

Within the ICAM Investigation model, specific Task/Environment Conditions are provided that can lead to human error. For example, workplace factors such as those outlined below (poor lighting, housekeeping or visibility) can cause distractions, promote violations or result in poor decisions.

Task/Environment Conditions: Workplace Factors

Also specific human factors issues (fatigue, personal issues or change of routine) including those outlined below can greatly increase the probability of human errors occurring.

Task/Environment Conditions: Human Factors

The best way to illustrate the relationship between human factors and human error is via the use of a case study.

Case Study

The following case study is based on actual events; however names, locations and other identifying details have been changed.

On 19th March 2015 at approximately 15:40 Western Standard Time (WST) three passengers, departed their accommodation facility in a 200 Series Landcruiser wagon, bound for the West Australian town of Geraldton some 400km to the South West. At 17:30 WST and only 115km from their departure point on the unsealed Carnarvon-Mullewa Road, while travelling at approximately 100km/h, the front right wheel impacted a standing pool of water, resulting in the steering wheel sharply pulling to the right. The driver overcorrected with left input causing the vehicle to travel sideways, and control of the vehicle was lost as it ran off the left of the road colliding with several shrubs and small trees. None of the occupants of the vehicle sustained any injuries.

The impact with several shrubs and trees on the side of the road, resulted in a punctured front passenger side tyre as well as minor vehicle panel damage including a smashed indicator, and damage to the plastic liner of the wheel arch.

The vehicle was able to be driven back on to the road where the punctured tyre was replaced. The vehicle was then driven safely to Geraldton, by one of the passengers, without further incident.

The incident was reported by the original driver to the site manager via phone once back in mobile range.

Picture 1: Puncture damage to front passenger tyre.

Picture 2: Road conditions at the time of the incident.

While it was determined that the Actual Consequence of the incident was “Minor” with less than $2,500 damage to the Landcruiser, the Potential Consequence was determined to be “High” with the potential for fatal injuries to be sustained by the three occupants of the vehicle.

The ICAM model forms a practical way to analyse both the errors and human factors involved in this incident.

Analysis Overview

The basic cause of the incident was that the driver failed to maintain adequate control of the vehicle.

There are a number of contributing factors that exacerbated this:

  • The driver operated the vehicle at an inappropriate speed for the road conditions.

  • 4WD training provided to site staff and contractors is a one-off training course and there is no ongoing Verification of Competency (VOC) process.

  • The 4WD training package provides insufficient emphasis on driving techniques for wet gravel roads and role of passengers as a secondary defence in speaking up when concerned about safety.

  • The passengers in the vehicle did not identify the hazards about the speed of the vehicle given the wet road conditions.

Individual/Team Actions- These are the errors or violations that led directly to the incident. They must be ‘active failures’ – something that a person(s) did (or failed to do) in the presence of the hazard (driving) that directly led to the event?

So in the case of the vehicle incident; who did or did not do something that led to the driver losing directional control of the vehicle?

Using the ICAM methodology, let's have a closer look at the human errors and human factors involved based upon the evidence.

  • IT3 Operating Speed: The driver operated the vehicle at an inappropriate speed for the road conditions. While the driver was not exceeding the 110km/h posted speed limit, the driver by choosing to operate the vehicle at 100 km/h, through standing pools of water on the road, is evidence of not driving to the current road conditions.

  • IT11 Hazard management error: The vehicle passengers chose not to speak up about the inappropriate speed of the vehicle for the road conditions. The passengers admitted the driver was going "a bit fast" for the conditions but failed to speak up about their concerns.

Task/Environmental Conditions- These are the conditions in existence immediately prior or at the time of the incident that directly influence human and equipment performance in the workplace. It is important that only conditions are selected that influenced the behaviour. The conditions should link to the Individual/Team Actions previously identified.

So in our vehicle incident case study; what were the workplace and human factors conditions that resulted in the driver not driving to conditions and the passengers failing to express concern?

  • HF16 Experience/knowledge/skill for task: The driver did not adequately apply his experience in driving on wet gravel roads. Despite being an experienced driver in these conditions the driver failed to utilise that experience in choosing a more conservative speed and over correcting once directional control was compromised.

  • HF15 Distraction/ pre-occupation: The driver of the vehicle was keen to return home - “get home soon” mentality - which influenced the choice of speed. The driver's contract had ended and he was heading overseas for a holiday and the driver admitted he was focused on getting home rather than driving to the conditions.

  • HF1 Complacency/motivation/desensitisation to hazard: The passengers were desensitised to the journey to and from the site. The complacency felt by having done the journey many times and that things would be OK, was one of the influencing factors for the passengers failing to speak up.

  • TE22 Surface gradient/conditions: There were standing pools of water on the road from previous rain fall which resulted in the vehicle experiencing sideways movement and loss of directional control. The long ribbons of standing water on the road, mud and slurry; were challenging road conditions.

Recommended Corrective Actions

  • Issue a site wide safety alert warning drivers about importance of driving to the road conditions.

  • Ensure that the 4WD initial training or equivalent provided to staff and contractors adequately focuses on driving techniques for wet gravel roads and the importance of accompanying passengers expressing concern about unsafe driving practices.

  • The issues raised from this investigation should be widely disseminated throughout other company sites and business areas as part of demonstrating a visible learning culture. Any communication should also include a reminder of the importance of speaking out about observed “at risk behaviour”.

  • Implement a process for regularly assessing ongoing 4WD competency assessment to ensure skills are refreshed.

  • Site management formalise a regular education program on 4WD vehicle safety to continually highlight the “high risk” nature of this activity and reduce potential complacency.

NOTE: The incidence of vehicle incidents was extremely low on this site, despite several hundred thousand kilometers being travelled annually. Had the incident rate been higher, and it was possible to use alternative transport in this remote location, higher order controls such as substitution (different form of transport) or engineering controls (In Vehicle Monitoring Systems) may have been explored.

Key Learnings

  1. When driving in adverse conditions, reducing speed can assist in avoiding a loss of control of the vehicle.

  2. Even the most safety conscious staff can become complacent about the risks posed when driving on wet gravel roads.

  3. When you are concerned about a risk, then you should not hesitate to express concern.


Don't get confused between human factors and human errors. The former generally leads to the other. One good way to remember is the concept of fatigue. Saying someone is fatigued is NOT considered a specific error - it is a condition or state (physical and mental) of your body.

However, what fatigue may lead to; is poor decision making (mistake) or inattention (slip). Use the Task/Environment Conditions - workplace and human factors conditions causal codes in the ICAM pocket guide to identify some of the human factors issues.

But be warned - try to avoid a 'recipe' approach by just selecting a whole bunch of them from the list! Don't guess; more is not necessarily better! What evidence is there to support the inclusion of each chosen condition?

Interested in Knowing More?

Further information on Safety Wise’s Incident Cause Analysis (ICAM) Training is available from our website:

Additional ICAM Related Services

Safety Wise also offers the following additional services for sites that adopt the ICAM investigation analysis method:

  • Quality review of incident investigations using ICAM

  • Trend analysis of organisational factors contributing to serious incidents

  • Participation in investigations as an external / independent party


ABOUT THE AUTHOR- Dr Graham Edkins (Business Development Manager)

Graham was involved with the original development and rollout of the ICAM process while representing Qantas as Head of Human Factors in the late 1990's. Nearly 20 years later Graham's belief in the practical utility and continual improvement of ICAM as a bespoke incident investigation analysis tool for any workplace has not wavered.

Graham's commitment to improving the quality of incident investigations for high-risk industries originally stemmed from safety investigation roles in rail, aviation and for the Commonwealth Government as a Transport Safety Investigator. This commitment continued during his time as the Rail Safety Regulator for Victoria and as a Senior Executive with the Civil Aviation Safety Authority. What these roles have taught Graham is that it's possible to develop error-tolerant systems through data driven but practical strategies.

In his role as Business Development Manager for Safety Wise, Graham is involved in the ongoing improvement of the ICAM product and driving the quality application of its use within client organisations. With a focus on delivering practical and sustainable results, Graham is highly sought after as an expert on safety behaviour change, error management and the proactive application of ICAM.

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