14.2 Root Cause Analysis Techniques

14.2 Root Cause Analysis Techniques

Quick Answer: Use 5 Whys to drill a single causal chain until a controllable system failure appears; use an Ishikawa Fishbone to brainstorm causes across people, equipment, materials, methods, measurement, and environment—then verify each idea against evidence before writing actions.

Gathering facts without analysis produces a story. Analysis without facts produces a guess. ISPON HSE Level 3 expects supervisors to combine both: structured root cause analysis (RCA) that explains why defenses failed and what must change in the HSE management system.

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Why “Human Error” Is Not a Root Cause

Writing “carelessness” or “failure to follow procedure” as the final cause stops learning. Those phrases describe what someone did, not why the system allowed or encouraged it. Ask further: Was the procedure unusable at the worksite? Was training assessed or only attended? Were two supervisors giving conflicting instructions? Was the permit treated as a signature exercise? RCA ends when you reach a cause the organization can redesign—competence assurance, equipment reliability, task planning, supervision standards, or resource allocation.

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Technique 1: The 5 Whys

The 5 Whys method, popularized in lean/quality practice and widely taught in HSE courses, asks “Why?” repeatedly—often about five times—until underlying systemic failure is exposed. Five is a guide, not a law: stop when a controllable root is clear and evidence-backed; continue if you are still describing symptoms.

Worked Nigerian example

Event: Helper receives a laceration when a grinding disc fragments during hotspot grinding in a Warri contractor workshop.

1. Why was the helper injured? — Fragments struck his face/neck area.
2. Why did fragments strike him? — He was inside the fragment zone without adequate face protection / screening.
3. Why was he in the zone without protection? — No barrier was set and the supervisor allowed the helper to hold the workpiece by hand.
4. Why was that allowed? — The JHA did not require a fixture or screen for this disc size, and PPE compliance was not enforced for helpers.
5. Why were JHA and enforcement weak? — Supervisors were not coached on disc-speed/guarding rules, and weekly inspections did not check grinding set-ups.

Actionable roots: Update JHA/method for grinding (fixtures, screens, exclusion), enforce face shields for all persons near the task, coach supervisors, and add grinding set-up checks to inspections. Stopping at “helper stood too close” would miss the system fixes.

Good practice rules for 5 Whys

• Keep each answer factual and specific
• Prefer causes you can verify (worn guard missing, unsigned PTW, expired certificate)
• Avoid jumping to solutions mid-chain; finish the causal logic first
• If the chain branches (two independent failures), note both—or switch to Fishbone

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Technique 2: Ishikawa Fishbone Diagram

The Ishikawa or Fishbone diagram places the problem statement at the “head” and draws cause categories as bones. The common HSE/quality set is the 6 Ms:

Some teams use 4 Ms or add Management as an explicit bone. For exam purposes, recognize the standard Manpower, Machine, Material, Method, Measurement, Mother Nature/Environment grouping taught in Absolute HSE-style Level 3 outlines and practice banks.

How to run a Fishbone session

1. Write a precise problem statement (“Lost-time ankle fracture during offloading at Onne warehouse on 12 June—forklift fork struck pedestrian in marked walkway”).
2. Brainstorm candidate causes under each bone without criticizing ideas early.
3. Mark causes supported by evidence from Section 14.1 fact-gathering.
4. Circle priority roots that best explain the event and are controllable.
5. Convert priority roots into SMART actions (link back to investigation follow-up).

Fishbone prevents tunnel vision: a team obsessed with “pedestrian error” may miss missing spotters, faded floor markings, production pressure to rush offloading, or a reverse alarm that failed measurement/maintenance.

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Choosing and Combining Tools

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Evidence Discipline and Common Traps

• Trap — Stopping at the first plausible why: “He slipped because the floor was wet” needs further whys about drainage, housekeeping standards, and leak management.
• Trap — Cause = missing PPE only: Ask why PPE was missing and why higher controls were absent.
• Trap — Copy-paste actions: “Retrain all staff” with no competence check or procedure change rarely alters outcomes.
• Trap — Confidentiality breach: Share learning without unnecessary personal stigma; focus on system lessons in alerts.

Document the logic: attach the 5 Whys chain or Fishbone photo/scan to the investigation pack so auditors and clients see how conclusions were reached.

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Linking RCA to Controls and the HSE-MS

Root causes should map to durable controls:

• Competence and supervision → Clause 7 support / training matrices
• Method and PTW failures → operational control and permit discipline
• Machine/material failures → maintenance, procurement, and inspection regimes
• Environmental/SIMOPS issues → planning, area authority, and congestion management

Feed verified lessons into toolbox talks, induction updates, and management review inputs. That is how investigation becomes continual improvement rather than archive filler.

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Exam Focus Checklist

• Explain how 5 Whys peels symptoms to systemic failure
• List Fishbone 6 M categories and give one example each
• Distinguish immediate cause vs root cause inside an RCA story
• Reject “blame the worker” as a complete analysis

Mastering these techniques lets you defend investigation quality under client audit and under ISPON Level 3 scenario questions.