What Are Human Factors in Incident Investigation?

Two investigators are reviewing the same incident.

• One asks: “Who failed to follow the procedure?”

• The other asks: “What do we need to understand before we can explain why the procedure was not followed?”

Both questions concern the same event, but they lead the investigation in different directions.

The first begins with a deviation and looks for the person responsible. The second treats the deviation as still requiring explanation. It invites the investigator to examine what the people involved knew, what they were trying to achieve, what information they relied on and what conditions shaped their decisions. That is what Human Factors brings to incident investigation.

Human Factors is not simply a category of possible causes. Nor is it a softer alternative to accountability. It is a perspective that helps investigators examine behaviour in context rather than treating individual actions as the final explanation.

Applied well, it changes how an investigation is scoped, how evidence is gathered, how interviews are conducted and how conclusions are reached.

Human Factors Changes the Starting Point of an Investigation

An investigation often begins with a visible action. Someone selected the wrong setting, missed a warning, skipped a check or departed from a procedure. Because the action is close to the outcome, it can quickly become the main explanation.

A Human Factors perspective asks the investigator not to stop there.

The action is treated as a finding to be explored rather than a conclusion in itself.

Instead of moving directly from “The operator did not complete the check” to “The incident was caused by a failure to follow procedure”, the investigator considers what remains to be understood about the task, the available information, and the circumstances under which the action took place.

The central question becomes: "What do we need to understand before we can judge this action?". This does not assume that the action was justified. It ensures that judgement follows understanding.

This starting point protects the investigation from an early and narrow explanation. It also creates space to identify influences that may otherwise remain hidden.

Human Factors Helps Investigators Reconstruct the Situation

People involved in an incident acted before the outcome was known.

Investigators work afterwards. That difference matters.

Once an incident has occurred, the sequence can appear clearer than it was at the time. A warning may look obvious. A missed opportunity may seem difficult to understand. A decision may appear irrational because the investigator knows where it led.

A Human Factors perspective asks the investigator to reconstruct the situation from the viewpoint of the people involved.

• What could they see?

• What did they know?

• What did they expect to happen?

• What had previous experience taught them?

• What options appeared to be available?

This means separating information that was available before the incident from information that only became clear afterwards.

For example, an alarm that appears highly significant after an equipment failure may have been interpreted differently at the time. It may have occurred repeatedly without consequence, cleared automatically or previously been treated as unreliable.

The investigator’s task is not to decide whether the alarm should have been recognised with the benefit of hindsight. It is to understand how it was interpreted in the actual situation. This reconstruction helps prevent hindsight from becoming evidence.

Human Factors Broadens the Evidence Base

A Human Factors investigation does not rely only on procedures, statements and technical records. It also examines the reality of the work.

That may involve observing the task, reviewing the workplace, testing the accessibility of information and comparing written instructions with everyday practice.

A procedure may appear clear when read in an office but prove difficult to use while wearing protective equipment. A control may be correctly labelled but hard to distinguish from the one beside it. A required check may be possible under normal conditions but difficult during an operational disturbance.

Understanding the reality of the work may take the investigator beyond statements, records and written procedures. The task, workplace, equipment, information flows, and normal working practices may all reveal why the formal description of work does not tell the complete story.

The purpose is not to search everywhere. It is to recognise when the evidence cannot be understood without examining the context in which the work was performed.

This evidence helps the investigator understand the difference between how work is expected to happen and how it is actually carried out. That difference is not automatically evidence of poor behaviour. It may indicate that the formal process does not fully reflect operational reality.

Human Factors Improves Investigation Interviews

Interviewing is one of the areas where a Human Factors perspective becomes most visible. A question such as: “Why did you ignore the procedure?” already contains an interpretation. It suggests that the person made a conscious decision to disregard a clear and workable requirement. It may lead to defensiveness and limit what the investigator learns.

A more exploratory question would be: “Can you talk me through how you approached the task?” This allows the person to describe the sequence before the investigator introduces assumptions about what should have happened.

Human Factors interviewing is not defined by a standard list of questions. It is reflected in the investigator’s willingness to understand what the person was trying to achieve, how the situation appeared and which influences were present before deciding what the behaviour meant. The quality of that enquiry depends on careful listening, appropriate follow-up and the ability to test an account without forcing it into an existing explanation.

These questions help reveal the person’s understanding of the situation. They can also uncover influences that may not initially appear in the evidence: informal expectations, unreliable signals, competing priorities, previous experience or differences between written and actual practice.

Human Factors does not make an interview less critical. Accounts still need to be tested against other evidence. It does, however, help the investigator gather information before deciding what that information means.

Human Factors Challenges Simple Behavioural Labels

Incident reports often contain labels such as:

• complacency;

• lack of awareness;

• poor attitude;

• failure to concentrate;

• risk-taking;

• human error.

These terms can create the appearance of an explanation without providing much investigative value. For example, stating that someone “lost situational awareness” does not explain:

• which information was missed;

• why it was difficult to detect;

• what else demanded attention;

• whether the system provided adequate feedback;

• how the situation developed over time.

Similarly, “complacency” may describe the investigator’s judgement about behaviour, but it says little about the circumstances that shaped it.

A Human Factors perspective asks the investigator to replace labels with evidence.

• What did the person do?

• What cues were available?

• How were those cues interpreted?

• What conditions influenced attention or decision-making?

• How did the task normally succeed?

This does not mean that behavioural concepts have no value. It means they must be used carefully and supported by a clear explanation.

A strong investigation describes the conditions and mechanisms involved. It does not depend on a label to do the explanatory work.

Human Factors Extends the Analysis Beyond the Individual

The person closest to the incident is often the easiest part of the system to examine.

Their actions are visible. Earlier decisions may be distributed across teams, departments and levels of management.

A Human Factors perspective encourages the investigator to follow the influences behind the action.

A deviation from procedure may relate to how the procedure was designed, tested, introduced or supervised. A missed warning may involve display design, alarm reliability or competing demands. An unsafe shortcut may have become normal because the prescribed method was impractical.

Following the influences behind an action may lead the investigation towards the design of the task, procedures, supervision, workload, maintenance or decisions made elsewhere in the organisation.

The evidence should determine how far the analysis extends. Human Factors simply prevents it from ending at the first visible human action when wider influences remain relevant.

This does not mean that every investigation must expand indefinitely. The evidence should determine the scope. Human Factors simply prevents the analysis from ending at the first visible human action when wider influences remain relevant.

Human Factors Supports Fairer Accountability

Understanding behaviour in context is sometimes interpreted as an attempt to avoid accountability. The opposite can be true. Accountability becomes more credible when it is based on a careful understanding of what happened.

Credible accountability requires an understanding of what the person knew and intended, which expectations applied and how the surrounding conditions influenced the available choices. Without that context, fundamentally different forms of behaviour can easily be treated as the same.

This distinction matters because not all deviations are the same.

A deliberate and reckless act is different from an adaptation that has become routine, a mistake encouraged by confusing design or a decision made under conflicting expectations.

Human Factors does not decide the organisational response. It provides a stronger factual basis for that decision. It also helps prevent accountability from being placed solely on the person at the sharp end while decisions elsewhere in the organisation remain unexamined.

Human Factors Strengthens Findings and Conclusions

A weak finding restates the event:

“The employee failed to complete the required check.”

A stronger finding explains why the check was not completed:

“The check was routinely postponed during start-up because the operator was required to monitor several changing process conditions at the same time, and the control system did not provide a reminder once the immediate workload had reduced.”

The second finding does not remove the individual action. It places that action within an explanatory context. This matters because findings shape conclusions.

When findings are built around individual failure, the conclusion is likely to focus on compliance, competence or attention. When findings describe the interaction between behaviour and working conditions, the conclusion can address the system that made the action more likely.

Human Factors therefore improves the quality of the investigation report.

It helps the report explain not only what happened, but how the circumstances combined to produce the outcome.

Human Factors Leads to More Relevant Corrective Actions

Corrective actions follow the explanation developed by the investigation.

When that explanation ends with individual non-compliance, the response is likely to focus on reminders, training or closer supervision.

When the investigation also reveals how the task, equipment or organisation shaped performance, different opportunities for improvement become visible.

The purpose is not to eliminate every possibility of error. It is to create conditions in which successful performance is more strongly supported.

Human Factors Is a Discipline of Investigative Curiosity

Human Factors is sometimes presented as a specialist topic to be added to an investigation. Its greater value lies in how it changes the investigator’s thinking.

It encourages the investigator to remain curious when an action appears obvious, to distinguish description from explanation and to test whether the evidence supports an early judgement.

A useful question throughout an investigation is: “What do we still need to understand before this action can be explained?” That question may lead to the task, the equipment, the procedure, the team or the organisation. It may confirm that an individual action was important. It may also reveal that the action was only the visible end of a much wider set of conditions.

Human Factors does not tell the investigator what conclusion to reach.

It helps ensure that the conclusion is reached through evidence rather than assumption.

Human Factors Makes the Investigation More Complete

Human Factors in incident investigation means examining behaviour in context.

It influences where the investigation starts, what evidence is gathered, how interviews are conducted and how actions are interpreted.

It challenges investigators to look beyond labels, reconstruct the situation as it appeared at the time and explore the conditions that shaped performance.

This does not make individual actions irrelevant. It makes their meaning clearer.

An investigation that establishes only what someone did may identify a deviation. An investigation that also explains why the action made sense can reveal what needs to change. That is the contribution of Human Factors to incident investigation.

It turns individual behaviour from the end of the explanation into the beginning of a more useful enquiry.

"Human Factors turns human error into questions, not a conclusion."

Explore more about Human Factors in Incident Investigation

If you would like to continue developing your investigation capability, you may also be interested in:

• The Problem with ‘Human Error’ as an Explanation Discover why ‘human error’ describes what happened but rarely explains the conditions that shaped the action.

• Interviewing Witnesses After an Incident

  Learn how open, non-judgemental questions help investigators understand what people knew, expected and experienced at the time.

• Observation Skills

  Explore why effective observation requires investigators to notice more than the most visible actions and evidence.

• Learning from Incidents

  Discover how stronger investigations create the understanding organisations need to improve systems, strengthen learning and prevent recurrence.