What is Risk/Safety Analysis (FTA/FMEA/HAZOP)?
Risk and safety analysis, told as a story about the student council systematically tracing a near-accident at festival setup, using three methods.
A near-accident happened while setting up the festival.Nobody got hurt this time — but next time it could be a real accident.
Guessing at the cause on the spot gets it wrong.Guessing without a method misses the real cause — and the next risk.
Risk/safety analysis is three systematic ways to find accident causes and risks.The three look at different things but share a goal — finding risks before an accident.
Use FTA to trace the causes of an actual or feared accident; use FMEA or HAZOP to find failures in advance.To trace back from an accident, use FTA — to scan parts and steps ahead, use FMEA/HAZOP.
Analysis doesn't mean an accident can never happen.Analysis lowers the odds of an accident — it doesn't guarantee safety.
Risk/safety analysis = three methods for catching trouble early — FTA (tracing causes backward), FMEA (checking each part), and HAZOP (scanning each step with guide words).
FTA (Fault Tree Analysis) places a top (undesired) event at the root and decomposes it into contributing causes through logic gates (AND/OR), estimating root causes and likelihood. FMEA (Failure Mode and Effects Analysis) walks through each component's possible failure modes and effects, ranking risk priority by severity, occurrence, and detection. HAZOP (Hazard and Operability Study) applies guide words — too much, too little, none, reverse, other — to each step of a process to systematically find deviations. All three aim to reduce accidents, but none fully escape the limits of the analyst's own experience and imagination.
When grown-ups say it
- FTA (Fault Tree Analysis)
- A tree that traces backward from an accident to its causes. Logic gates show how causes combine.
- FMEA (Failure Mode and Effects Analysis)
- A table checking "what if this fails?" for every part. Ranks failures by severity, occurrence, and detection.
- HAZOP
- A scan using guide words like too much, too little, none. Walks through a process one step at a time.
- Risk Assessment
- Gauging how big and how often a risk is. All three methods are tools that feed into this.
- Root Cause Analysis
- Finding the real cause, not just the visible symptom. FTA is one of its representative methods.
- Failure Mode
- The specific way a single part can break. FMEA lists the ones a team can foresee for each part.
- Guide Word
- HAZOP's fixed set of prompting words. Works like a checklist that keeps the scan from skipping anything.
- Functional Safety Standard
- The official standard that grades the risks these analyses find. A separate standard turns this analysis into a safety grade. → the shared rulebook that grades safety