Root Cause Analysis (RCA): Systematic Approaches to Incident Investigation

Introduction

In high-risk industries such as oil & gas, manufacturing, and construction, incidents can lead to catastrophic consequences if not properly investigated and addressed. Root Cause Analysis (RCA) is a systematic method used to identify the fundamental causes of failures, accidents, or process deviations. By applying structured RCA methodologies, organisations can prevent recurrence, improve safety, and enhance operational reliability.

This blog explores key RCA techniques, their applications, and how they contribute to robust safety management.

Understanding Root Cause Analysis (RCA)

RCA is not just about identifying what went wrong, it seeks to understand why it happened. The primary objective is to uncover underlying systemic issues rather than just addressing surface-level symptoms.

Key Principles of RCA

• Systematic Approach – RCA follows a structured methodology rather than relying on assumptions.

• Focus on Prevention – It aims to eliminate the root cause to prevent recurrence rather than just fixing immediate issues.

• Evidence-Based Investigation – Decisions are based on data, physical evidence, and structured analysis.

• Multidisciplinary Collaboration – RCA involves input from multiple disciplines to gain a comprehensive perspective.

RCA Methodologies: Choosing the Right Approach

Different RCA techniques are used based on industry requirements, complexity, and nature of the incident.

1. 5-Whys Analysis

A straightforward technique that helps identify the root cause by repeatedly asking “Why?” until the fundamental issue is uncovered.

Example:

Incident: A worker slipped and fell on a wet floor.

• Why did the worker fall? → The floor was wet.

• Why was the floor wet? → There was a leak from a nearby pipe.

• Why was the pipe leaking? → A gasket had failed.

• Why did the gasket fail? → It was not replaced during maintenance.

• Why was it not replaced? → Maintenance procedures did not include routine checks for wear.

Root Cause Identified: Lack of preventive maintenance procedures.

2. Fishbone Diagram (Ishikawa Analysis)

Also known as the Cause-and-Effect Diagram, this method visually maps potential causes across key categories:

• People (human factors)

• Process (workflow, procedures)

• Equipment (machinery, technology)

• Materials (quality, compatibility)

• Environment (weather, working conditions)

• Management (leadership, decision-making)

Application:

Used in complex investigations where multiple contributing factors exist, such as process failures in chemical plants or mechanical breakdowns in heavy industries.

3. Fault Tree Analysis (FTA)

A top-down approach used in high-risk industries, FTA begins with a failure event and works backward to determine possible causes using logic gates (AND/OR).

Example Use Case:

• Aircraft engine failure analysis

• Explosion investigations in process safety

• Industrial equipment failure in petrochemical plants

4. Failure Mode and Effects Analysis (FMEA)

FMEA identifies failure modes, their impact, and likelihood, prioritising risks based on Risk Priority Numbers (RPN).

Industries Using FMEA:

• Aerospace and automotive

• Medical device manufacturing

• Chemical process safety

5. Bowtie Analysis

A combination of Fault Tree (causes) and Event Tree (consequences), Bowtie Analysis helps visualise barriers that prevent incidents from escalating.

Common Applications:

• Major accident hazard management

• Process safety in oil & gas

• Occupational safety risk control

Implementing RCA: Best Practices for Organisations

1. Establish a Structured RCA Framework

• Develop standardised RCA procedures within the organisation.

• Assign trained investigators to lead RCA sessions.

2. Use a Multidisciplinary Approach

• Involve HSE, engineering, operations, and management teams.

• Encourage open discussions to identify systemic failures.

3. Integrate RCA Findings into Continuous Improvement

• Implement corrective and preventive actions (CAPA).

• Track effectiveness through audits and key performance indicators (KPIs).

4. Leverage Technology for RCA Investigations

• Use software tools to document RCA findings systematically.

• Apply data analytics for trend analysis and predictive insights.

Case Study: RCA in Process Safety

Incident: Uncontrolled Chemical Reaction in a Refinery

A refinery experienced a runaway reaction in a reactor vessel, leading to a fire.

RCA Approach:

• 5-Whys: Identified a procedural lapse in temperature monitoring.

• Fishbone Diagram: Highlighted multiple contributing factors—operator error, lack of training, and outdated SOPs.

• FTA: Pinpointed failure of the temperature sensor as a critical trigger.

Corrective Actions:

• Upgraded sensors with real-time monitoring.

• Implemented operator training programs.

• Revised SOPs with enhanced safety barriers.

Outcome: Similar incidents were prevented, and compliance with process safety regulations improved.

Conclusion

Root Cause Analysis is an essential tool for incident investigation, helping organisations uncover underlying failures and prevent recurrence. By integrating structured RCA methodologies like 5-Whys, Fishbone Diagrams, FTA, FMEA, and Bowtie Analysis, industries can enhance safety, compliance, and operational efficiency.

Organisations that proactively apply RCA will not only resolve immediate issues but also build a culture of continuous improvement—ensuring safer workplaces and more resilient safety frameworks.