Root cause analysis

Category: Risk identification & assessment · Reviewed by Simon Temme, Account Executive · Last reviewed

Root cause analysis

Root cause analysis (RCA) is a structured method for identifying the underlying cause(s) of an incident, defect or near-miss, rather than treating its visible symptoms. It is typically a retrospective technique applied after an event has occurred, in contrast to forward-looking techniques like FMEA or HAZOP.

Common techniques

• Five Whys — repeated “why?” questioning to peel back layers of causation.
• Fishbone (Ishikawa) diagram — categorising contributing causes under headings such as People, Process, Equipment, Environment, Materials, Management.
• Fault Tree Analysis (FTA) — top-down deductive logic mapping with AND/OR gates.
• Event Tree Analysis (ETA) — forward-looking from an initiating event through success/failure of barriers.
• Cause-and-effect mapping — broader investigation tying multiple causes to outcomes.
• TapRooT, ECFA, MORT — proprietary RCA systems used in major industries.

Levels of cause

A disciplined RCA distinguishes:

• Immediate cause — the direct, proximate trigger (e.g. operator pressed the wrong button).
• Underlying cause — the conditions that allowed the immediate cause (e.g. inadequate training).
• Root cause — the systemic factor (e.g. no formal competency assurance regime).

Action plans targeting only the immediate cause produce recurrence.

Insurance and claims context

RCA is a standard component of large-loss claims investigation, particularly in marine, aviation, energy and product liability claims. Loss adjusters’ RCA reports often determine coverage outcomes under specified perils policies and subrogation strategy.

References

• IEC 31010:2019, Annex B.16.
• HSE HSG48 — Reducing error and influencing behaviour.
• US Department of Energy (1992, revised). Root Cause Analysis Guidance Document.

Cross-references

• Five Whys
• Fishbone diagram
• Ishikawa diagram

---

Maintained by Matt Bartlett, Director, Apex Insurance Brokers Limited. FCA FRN 724952. Companies House 07014570.