Root Cause Analysis (RCA) — Methods, Tools & Best Practice
BY RiskoPilot Editorial Team · LAST REVIEWED 2026-07-11
Root cause analysis (RCA) is the systematic identification of the underlying causes of an incident, defect or non-conformance — not just its symptoms. Different RCA methods trade off speed against depth: 5 Whys and Fishbone are fast and linear; ICAM adds absent/failed defences; Tripod Beta and BowTie classify organisational failures. Choose the method by severity, causation complexity and audience.
The five common RCA methods
1) 5 Whys — iterative why-questioning, fastest, single-thread. 2) Fishbone (Ishikawa) — categorises causes across 6 M's (Man, Method, Machine, Material, Measurement, Milieu). 3) Fault Tree Analysis — top-down Boolean logic diagram, quantitative. 4) ICAM (Incident Cause Analysis Method) — mining/aviation-heritage, classifies absent/failed defences. 5) Tripod Beta — Shell-developed, classifies latent organisational failures across eleven General Failure Types. RISKOPILOT specialises in the last.
How to choose the right method
Match the method to the incident: single-thread, low-severity, ops-only audience → 5 Whys. Multi-cause, cross-functional, needs a visual → Fishbone. Quantitative reliability engineering → Fault Tree. Aviation/mining, absent defences → ICAM. Process-safety, high-severity, latent organisational failures, regulator audience → Tripod Beta or BowTie. Rule of thumb: use the deepest method the incident severity justifies, no deeper.
Why 'root cause' can be a misleading term
Modern safety science (Reason 1990, Hollnagel, Dekker) argues that complex incidents rarely have a single root cause — they have a converging pattern of active failures, preconditions and latent organisational weaknesses. That's exactly what the Swiss Cheese Model and Tripod Beta try to capture. When you see a 5 Whys report ending at 'operator error', treat it as a symptom of the analysis method, not of the incident.
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