Framework
Root Cause

Fault Tree

AND/OR logic of failure paths

Best for
reliability engineering analysis
Time
1–2 hr
Difficulty
Advanced
Example

Reliability engineering: tracing how the API returned 5xx

Fault tree branches
  1. Top event — API returns 5xx to customer
  2. OR — gateway returns 5xx (timeout OR memory exhaustion)
  3. OR — app server returns 5xx (downstream DB OR config bug)
  4. AND — DB failure requires (primary down AND failover misconfigured)
  5. Action: harden gateway timeouts AND test failover quarterly

Related frameworks

Root Cause

Fishbone Diagram

Causes grouped under 6 Ms

Root Cause

Current Reality Tree

Logical tree of undesirable effects

Root Cause

A3 Problem Solving

One-page Toyota problem report

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