Root cause analysis - Fault Tree Analysis

Root Cause Analysis (RCA) - A structured evaluation method that identifies the root causes for an undesired outcome and the actions adequate to prevent recurrence. Root cause analysis should continue until organizational factors have been identified, or until data are exhausted.
  1. Identify and clearly define the undesired outcome (outage).
  2. Gather data.
  3. Create a timeline.
  4. Place incidents and conditions on an event and fault tree.
  5. Using the fault tree identify all potential causes.
  6. Break down system failures to a basic events or conditions (further describe what happened).
  7. Identify specific failure modes (immediate causes).
  8. Continue asking “WHY” to identify root causes (five times).
  9. Check your logic and your facts. Eliminate items that are not causes or contributing factors.
  10. Generate solutions that address both proximate causes and root causes.
Timeline template

Proximate Cause(s) (Direct Cause)The event(s) that occurred, including any condition(s) that existed immediately before the undesired outcome, directly resulted in its occurrence and, if eliminated or modified, would have prevented the undesired outcome.
Root Cause(s)One of multiple factors (events, conditions or organizational factors) that contributed to or created the proximate cause and subsequent undesired outcome and, if eliminated, or modified would have prevented the undesired outcome. Typically multiple root causes contribute to an undesired outcome.