Written by Senior Consultant, Pete Hibbert
In the world of aviation and other safety-critical industries, understanding why things go wrong is just as important as knowing what went wrong. At the heart of that understanding lies Human Factors (HF) - 'The discipline of optimising human performance in the workplace'. When conducting safety investigations, HF is not merely a supportive concept; it is a foundational lens through which incidents must be explored. As Professor James Reason stated, "We cannot change the human condition, but we can change the conditions under which humans work" and to do that, we must understand those conditions.
Why Human Factors Matter
When humans contribute to a bad outcome, it is rarely the result of carelessness or incompetence. The overwhelming majority of people in safety-critical industries come to work with the intent to perform well. Unwanted events typically arise from a complex interaction of systemic issues, conflicting goals, workload, organisational pressures, and latent conditions, not isolated acts of individual failure.
According to Boeing (MEDA data), approximately 80% of human errors originate from factors under management control, reinforcing the concept that safety is not an individual issue, but a systemic one.
Beyond Blame: Understanding Behaviour
One of the most transformative shifts in safety investigations has been the move away from blame and towards understanding. This aligns with Reason's argument that blaming individuals does not improve system safety. Investigators must recognise and mitigate psychological shortcuts such as outcome bias, hindsight bias, and the fundamental attribution error, which can lead us to judge decisions solely by their outcomes, rather than the information and context available to the person at the time.
As Professor Sidney Dekker explains in his "Tunnel Concept", investigators should aim to reconstruct the local rationality, not asking "Who is at fault?" but instead considering:
- What did the world look like to the individual at the time?
- What were they trying to achieve?
- What constraints and pressures were they facing?
- Where was their attention focused?
- What tools, information and training were available to them?
This humanistic and contextual approach enables investigators to understand decisions and actions in their authentic setting, thereby producing more meaningful and actionable findings.
Investigative Interviewing: Supporting the Cognitive Interview with PEACE
Central to uncovering the human factors behind events is the interview process. Yet traditional approaches often fall short in capturing accurate, unbiased accounts of what happened and why. This is where the work of Professor Becky Milne becomes particularly influential. A pioneer in investigative interviewing, Professor Milne's techniques emphasise the use of the Cognitive Interview (CI) to enhance memory retrieval and reduce the risk of distortion or suggestion.
Through our collaboration with Professor Milne, Baines Simmons has embedded the Cognitive Interview approach into our Practical Skills for Investigators course, ensuring that interviews support fair, thorough, and context-rich investigations.
During the course, we explore how the CI is most effective through the use of the PEACE model of interviewing:
- P - Planning and Preparation
- E - Engage and Explain
- A - Account and Clarification
- C - Closure
- E - Evaluation
This model, rooted in ethical and evidence-based practice, supports non-coercive, empathetic, and open-ended questioning, allowing investigators to build rapport, reduce stress for the interviewee, and encourage detailed, reliable recollections. PEACE also aligns with the Just Culture principle of treating people fairly and respectfully, essential for encouraging open reporting and learning.
Through this structured yet flexible approach, trained investigators are better equipped to identify the cognitive, organisational, and environmental factors that shaped someone's behaviour.
Classifying Human Behaviour to Tailor Interventions
The Baines Simmons Practical Skills for Investigators course also introduces the FAiR (Flowchart Analysis of Investigation Results) system, which investigators use after the fact to help identify the most appropriate systemic interventions, based on behaviours because, as Reason reminded us, "You cannot change human behaviour by simply telling people to try harder."
For example:
- A slip (of the memory) may result from attentional capture and require adjustments to task design or environment.
- A mistake may indicate a knowledge gap and suggest the need for improved training or procedures.
- A violation may reflect cultural or systemic normalisation and require addressing organisation expectations or incentives.
Interventions must be effective, efficient and enduring, designed to prevent recurrence, not to punish error. The focus should remain on strengthening defences, addressing system weaknesses, and enabling people to succeed.
Building a Just Culture Through Investigation
A consistent theme throughout the Baines Simmons Practical Skills for Investigators course is the pivotal role of the investigator in reinforcing Just Culture. A high-quality safety investigation conducted fairly, objectively, and empathetically sends a clear message: that the organisation values truth over blame, context over outcome, and learning over punishment.
This is how investigators contribute to creating a culture where people are willing to speak up, share, and contribute to safety improvement, a culture that sustains resilience and continuous learning.
Conclusion
Human Factors are not a side note in safety investigations, they are often the central story. Through the thoughtful application of models like FAiR, structured interviews using PEACE, and a Just Culture mindset, safety investigators can uncover the real reasons behind human actions.
By understanding the human context, we move beyond blame and to where learning and improvement are embedded in our response to failure.
Whether you're an investigator, manager, or frontline operator, embracing Human Factors is essential to building safer systems, stronger teams, and a more just and accountable safety culture.
Learn more about the Baines Simmons Practical Skills for Investigators course and the FAiR system.