Why a Single Root Cause in an Investigation is Not Enough

Introduction

In the aftermath of a workplace incident, one of the most common questions asked by managers, regulators, and the public is: “What was the cause?” The expectation, almost instinctive, is that there must be a single factor- a clear root cause, that explains everything. This desire for simplicity is understandable. A single cause implies a single fix. It creates a sense of closure and accountability. It fits neatly into reports, headlines, and executive briefings.

Yet, as decades of safety science and investigative practice have shown, the idea that a single root cause can fully explain an incident is not only misleading but also dangerous. Incidents are rarely the result of one decision, one error, or one failure. Instead, they are the outcome of complex interactions between people, processes, technology, and organisational systems. By reducing an investigation to a single root cause, we risk missing the true lessons, repeating the same mistakes, and failing to create safer workplaces.

This article explores why a single root cause is not enough. Drawing on safety models, real‑world case studies, and investigative frameworks like ICAM, we will examine the limitations of root cause thinking and make the case for a systemic, multi‑factorial approach to investigations.

The Problem with the “Single Root Cause” Mentality

Oversimplification of Complex Events

Most incidents occur within complex systems where multiple variables interact. Isolating one “root” cause oversimplifies reality. For example, a machinery accident may be attributed to an operator error, yet a deeper look often reveals inadequate training, poor maintenance schedules, flawed design, and production pressures that all contributed.

Human Error as a Convenient Scapegoat

The most common “root cause” written in investigation reports is “human error.” While appealing in its simplicity, this explanation is rarely the real story. Declaring that someone “failed to follow procedure” doesn’t explore why the procedure was difficult to follow, whether it was practical, or whether systemic pressures made deviation likely. Human error is not a cause- it is a symptom of deeper issues.

Missed Organisational and Systemic Contributors

By focusing on a single root cause, organisations often miss the broader picture. Organisational culture, management decisions, and latent conditions frequently play a larger role than the immediate act that triggered the event. For example, an accident caused by a “faulty harness” may trace back to procurement policies that prioritised cost over quality, inspections that were rushed, and supervisors who felt pressured to meet deadlines.

The Illusion of Closure

When a single root cause is identified, there is a false sense that the problem has been solved. The box is ticked, the corrective action applied, and attention moves on. But in reality, underlying risks remain. This illusion of closure can be more dangerous than the incident itself, because it prevents the organisation from learning and adapting.

Understanding Incident Causation

Complex Adaptive Systems

Workplaces, particularly in high‑risk industries, operate as complex adaptive systems. These systems cannot be fully understood by looking at components in isolation. Incidents emerge not from one factor but from the interactions between people, technology, and environment.

The Swiss Cheese Model

James Reason’s Swiss Cheese Model illustrates how multiple layers of defence exist to prevent incidents. Each layer has holes (weaknesses), and when those holes align, an incident occurs. No single hole is responsible; it is the alignment across multiple layers that creates vulnerability.

Latent Conditions vs. Active Failures

Active failures are the errors and unsafe acts visible at the time of the incident. Latent conditions are hidden weaknesses in the system, such as poor design, resource shortages, or flawed policies. A single root cause approach almost always stops at the active failure, ignoring the latent conditions that made it possible.

The ICAM Framework

The ICAM (Incident Cause Analysis Method) framework recognises four levels of contributing factors:

• Absent or Failed Defences

• Individual and Team Actions

• Task and Environmental Conditions

• Organisational Factors. By analysing across these dimensions, ICAM prevents the trap of single‑cause thinking and enables organisations to see the full picture.

Case Studies: The Danger of Single Root Cause Thinking

Aviation: Tenerife Airport Disaster

The 1977 collision of two Boeing 747s at Tenerife, killing 583 people, was initially attributed to a single pilot’s decision to take off without clearance. However, deeper investigation revealed multiple contributors: poor radio communication, language barriers, airport congestion, fog, and inadequate procedures. If the investigation had stopped at “pilot error,” aviation safety would have missed crucial reforms.

Mining: Pike River Mine Explosion

The 2010 Pike River disaster in New Zealand, which killed 29 miners, was at first described as a methane explosion. But investigations revealed broader systemic issues: inadequate ventilation, poor regulatory oversight, cost‑cutting by management, and a culture that discouraged raising concerns. The disaster was not about gas alone; it was about governance, culture, and priorities.

The Value of Multi‑Cause, Systemic Investigations

Comprehensive Barrier Analysis

Rather than searching for a single cause, systemic investigations look at all barriers that should have prevented the incident and why they failed. This approach highlights multiple opportunities for improvement instead of just one.

Identifying Organisational Factors

Organisational contributors- such as inadequate training, weak safety leadership, or flawed maintenance programs — are often the real drivers of incidents. Systemic investigations bring these to light, enabling change at the level that matters most.

The Role of Leadership and Culture

Culture is a powerful influencer of safety behavior. A culture that rewards productivity over safety almost guarantees repeated incidents. Multi‑cause investigations expose cultural drivers that single‑cause thinking overlooks.

Building Resilience and Learning Capacity

By looking beyond the root cause, organizations build resilience. They learn to recognize patterns, strengthen defenses, and adapt systems, reducing the likelihood of recurrence even in different circumstances.

How to Move Beyond Root Cause

Ask Better Questions

Instead of asking “What caused this?” ask:

• “What were the conditions that made this possible?”

• “Why did the barriers we expected to protect us fail?”

• “What decisions set the stage for this incident?”

Use Structured Frameworks

Frameworks like ICAM guide investigators to explore systemic and organisational factors, preventing the trap of single‑cause thinking.

Incorporate Human Factors and Just Culture

Recognising that humans will make errors, Just Culture approaches focus not on blame but on understanding why the error occurred and how systems can be designed to mitigate it.

Develop Effective Recommendations

Single‑cause investigations produce narrow corrective actions. Systemic approaches generate broader recommendations that address training, supervision, culture, and organisational resilience.

Addressing the Pushback Against Multi‑Factor Analysis

Why Managers Still Ask for “The Cause”

Leaders often want a simple answer for accountability and reporting. The challenge for investigators is to communicate complexity clearly without overwhelming the audience.

Balancing Simplicity with Accuracy

The key is to present findings in a way that shows the interplay of factors without drowning in detail. Visual models, timelines, and layered summaries can help.

Communicating Complexity Effectively

Using frameworks like ICAM ensures findings are structured, logical, and accessible. Senior leaders can see both the immediate factors and the deeper systemic issues in a way that drives meaningful action.

Conclusion

The notion of a single root cause is outdated and inadequate in today’s complex workplaces. While it may satisfy the demand for quick answers, it fails to capture the reality that incidents are shaped by multiple, interacting factors, from human decisions and task conditions to organisational culture and systemic weaknesses.

If organisations are serious about preventing recurrence, they must move beyond root cause thinking. Tools like ICAM show us that learning comes from recognising the web of contributing factors, addressing them collectively, and strengthening the system as a whole. Only then can we truly honour the lessons of past incidents and build safer, more resilient workplaces.

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