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The Thinking Cap


The Human Factors Analysis and Classification System

Article prepared: 28 February 2014

It has been said before that one incident is one too many. However, given that humans by their very nature make mistakes, how do we prevent a disaster? To answer this question we should look to the innovative world of human factors and focus on learning from our past mistakes and errors. A great example of progress in human error prevention is the Human Factors Analysis and Classification System (HFACS). This human error framework, developed within the U.S. military, tackles human error at every level of the organisation, namely the physical and mental state of humans as well as potential organisational influences.

The Four Levels of Human Failure

HFACS is based on Reason’s (1990) four levels of human failure (commonly known as the Swiss Cheese Model), which, when you work backwards from unsafe acts, establishes that each level of failure impacts drastically on the next. The following breakdown of these four levels provides us with insight into where involvement of the human factor can lead to an error or mistake being made.

Unsafe Acts

Will we ever be able to prevent all unsafe acts from occurring? Probably not. However, understanding what classifies an unsafe act brings us a step closer to implementing the right tools to minimise the risk of negative outcomes. We can classify these acts into two categories: errors and violations.

  1. Errors: Generally encompassing skill-based (memory lapses and slips in attention), decision based (intentional behaviour with an undesired outcome, an “honest mistake”), and perceptual error (when perception of a situation is different from the reality).
  2. Violations: A wilful disregard for safety rules, often resulting in severe consequences. Two distinct forms of violation have been identified:
    1. Routine violations - the breaking of a safety rule or procedure is the normal way of working. It becomes routine not to use the documented procedures for tasks. 
    2. Wilful violations – an isolated departure from the rules, a wilful violation can occur in overcoming an unworkable situation or can, albeit rarely, be the result of an employee’s desire to do something they know they’re not supposed to.

Preconditions for Unsafe Acts

We cannot focus on an unsafe act without also analysing the reasons for why this act occurred. Did the operator have inadequate training? Were they suffering from fatigue? It is vital that we look beyond the act itself to have a hope of preventing someone else from repeating it. HFACS established two major subdivisions of unsafe conditions:

  1. Substandard conditions of operators:
    1. Adverse mental states - mental conditions that may affect performance (e.g. distraction, task obsession, and mental fatigue).
    2. Adverse physiological states - medical or physical conditions that prevent safe operations.
    3. Physical/mental limitations - when the job requires more than the person may be able to achieve (e.g. environmental conditions such as night time driving on a long straight road which demands a large increase in attention and alertness). This can also encompass an individual’s general ability for a role.
  2. Substandard practices of operators:
    1. Employee resource management - poor coordination within and amongst teams (e.g. failure to radio operators on mobile plant or equipment).
    2. Personal readiness – the expectation that individuals will turn up to work ready to perform. Failures occur when individuals do not prepare mentally or physically for work (e.g. at least 8 hours sleep before working a 12 hour shift).

Unsafe Supervision

When we look at the conditions and practices of our operators as contributing to failure, it would be only natural to look at the role their supervisors play as well. HFACS has identified four categories of unsafe supervision:

  1. Inadequate supervision: If guidance and direction from supervisors is non-existent, violation of procedures is more likely to occur. For example, this could happen when a supervisor is working on the tools instead of supervising his team members.
  2. Planned inappropriate operations: Operational demands have been known to impact time and scheduling, at times putting workers at risk and affecting their performance. These periods, though occasionally unavoidable in emergency situations, are unacceptable for standard operations. This category has been created specifically to account for failures that occur due to out of the ordinary circumstances.
  3. Failure to correct a known problem: Sometimes a supervisor may know that a team member is cutting corners or that a piece of equipment isn’t quite up to spec, but for whatever reason, doesn’t address it. This failure to correct inappropriate behaviour or address issues with machinery works to foster an unsafe environment.
  4. Supervisory violations: This category is specific to those supervisors who wilfully violate rules and procedures to get a job done, laying the foundation for a potentially disastrous outcome (e.g. permitting individuals to operate machinery without current licenses).

Organisational Influences

Finally, decisions made at the top level of the organisation must be addressed, given that they impact upon personnel practices across the entire organisation. Failures at the organisational level consist of:

  1. Resource management: Decision making which is focused on two objectives – safety and cost-effective, productive operations. It is not uncommon for safety to be the loser, with training and safety budgets often getting the boot in times of financial strife. This has the concerning knock-on effect of poorly trained employees and poorly maintained equipment lending itself to potential for injury and incidents.
  2. Organisational climate: The working atmosphere within the organisation, what it looks like at any given time. This can be evidenced by its structure, policies, and culture. When these are poorly defined, conflicting or not actively supported from the top of the organisation, confusion tends to result down the levels and safety can end up suffering.
  3. Operational processes: Decisions and rules made at the top level that direct everyday activities within the organisation. These commonplace decisions can potentially have an adverse effect on safety (e.g. increased time pressure to meet deadlines and lengthening work schedules).

Each of these human factors can influence one another and are not independent behaviours. So often an error at an operator level may stem from a management decision at the upper levels of the organisation. Certainly, any analysis of human factors should investigate all levels of the organisation, not just the operator.

How can PSB Solutions help?

PSB Solutions understands that managing risk when it comes to human beings is no easy task.  Understanding the capabilities and limitations of your workforce to ensure the best possible fit between people and the systems in which they operate is a vital step to doing this.

PSB Solutions can assist your organisation in human factor management in the following ways:

  • safety leadership training encompassing human factors; and
  • Human Factors in Systems Analysis (an in-depth analysis of the human factors required to ensure systems are working properly).

For more information, or if you would like to have a discussion regarding what you’ve read today, please contact us on (08) 9489 3900 or email us.


Reason, J. (1990). Human error. New York: Cambridge University Press.
Shappell, A.S. (2000). The Human Factors Analysis and Classification System – HFACS. US Department of Transportation, Federal Aviation Administration. 


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