23/06/2026
ROOT CAUSE ANALYSIS (RCA) METHODS
Different Tools – One Goal: Prevent Recurrence
Root Cause Analysis (RCA) is a systematic process used to identify the actual reason behind an incident, accident, near miss, or problem. The objective is not to blame people but to find the real cause and prevent the incident from happening again.
1. 5 WHY ANALYSIS
What is it?
The 5 Why Method is a simple technique where we repeatedly ask "Why?" until we reach the root cause.
Example:
Incident: Worker slipped and fell.
Why 1? Because the floor was wet.
Why 2? Because water leaked from a pipe.
Why 3? Because the pipe was damaged.
Why 4? Because inspection was not conducted.
Why 5? Because there was no preventive maintenance schedule.
Root Cause:
Lack of preventive maintenance.
Best Used For:
Simple incidents
Near misses
Minor accidents
2. FISHBONE DIAGRAM (ISHIKAWA)
What is it?
A visual tool used to identify possible causes of a problem by categorizing them into different factors.
Common Categories:
👷 People
⚙️ Machine
📋 Method
🧱 Material
🌦 Environment
🏢 Management
Example:
Problem: Frequent hand injuries.
Possible causes:
Lack of training
Defective tools
Unsafe work methods
Poor supervision
Best Used For:
Complex problems
Team brainstorming
Multiple possible causes
3. BARRIER ANALYSIS
What is it?
Barrier Analysis identifies which safety barrier failed, was missing, or was ineffective.
Example:
Incident: Worker entered a restricted area.
Expected Barriers:
Warning signs
Physical barricades
Access control
Supervision
Finding:
Barricade was missing and supervision was inadequate.
Best Used For:
Safety system failures
Process safety incidents
High-risk operations
4. FAULT TREE ANALYSIS (FTA)
What is it?
FTA is a logical diagram used to identify combinations of failures that lead to an incident.
Example:
Top Event: Fire in electrical panel
Possible Causes:
Short circuit
Overloading
Poor maintenance
Damaged insulation
Best Used For:
Engineering systems
Electrical incidents
High-risk industrial facilities
5. EVENT & CAUSAL FACTOR ANALYSIS (ECFA)
What is it?
ECFA creates a timeline of events and identifies contributing factors.
Example:
08:00 AM → Machine started
08:30 AM → Abnormal vibration noticed
09:00 AM → Warning ignored
09:30 AM → Machine breakdown
Root Cause:
Early warning signs were not acted upon.
Best Used For:
Serious accidents
Multi-step incidents
Detailed investigations
6. TRIPOD BETA
What is it?
Tripod Beta examines three levels of causes:
A. Immediate Cause
What happened?
B. Underlying Cause
Why did it happen?
C. Organizational Cause
Why was it allowed to happen?
Example:
Worker fell from height.
Immediate Cause: No fall protection used.
Underlying Cause: Worker not trained.
Organizational Cause: No effective training management system.
Best Used For:
Major accidents
Corporate investigations
System failure analysis
7. BOW-TIE ANALYSIS
What is it?
Bow-Tie Analysis shows threats, preventive controls, consequences, and recovery controls in one diagram.
Example:
Threat ⬇ Gas Leak ⬇ Top Event ⬇ Gas Release ⬇ Consequences Fire / Explosion / Injury
Preventive Controls:
Gas detector
Inspection program
Preventive maintenance
Recovery Controls:
Emergency response plan
Firefighting system
Evacuation procedure
Best Used For:
Process safety
Chemical plants
Oil & gas industry
KEY TAKEAWAY
✅ 5 Why → Simple Problems
✅ Fishbone Diagram → Multiple Causes
✅ Barrier Analysis → Failed Safety Controls
✅ FTA → Technical & Engineering Failures
✅ ECFA → Event Timeline Analysis
✅ Tripod Beta → Organizational Causes
✅ Bow-Tie → Risk Visualization & Control Management
Conclusion
The purpose of RCA is not to find who caused the incident, but to find why it happened and how to prevent it from happening again.
Fix the System, Not the Blame.
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