Complete firstIncident datanot in catalog
Symptoms, relevant times, logs, alerts, or observations are available in raw form.
Without: Without a clear scope, the team collects material but cannot produce a robust structure or decision.
RunsheetEngineering
Fault Isolation
ComplexityMedium
Time30-180 min
Participants1-6
FormatWorkshop + async
MaturityEstablished
01
Prerequisite
What needs to be finished first
02
Preparation
What needs to be ready before start
Materials
Workspace or document for isolation map; existing notes, data, decisions, and assumptions; markers for uncertainty, owner, and next steps.
People / roles
Facilitator; domain experts from affected area; owner for outcome and follow-up; named decider for decisions.
Pre-read
Scope, occasion, known facts, relevant constraints, existing options or events, and desired meeting outcome.
Time needed
60-180 min
Setup
Prepare an empty Isolation Map template. Make scope and working question clearly visible at top. Mark each assumption as assumption, not fact.
03
Core question
The one question this method answers
Which system area most likely causes the symptom, and which tests narrow the fault domain further?
04
Flow
Marker: Phase
| Step | Duration | Action | Hint |
|---|---|---|---|
1Fix scope | 10-20 min | Define occasion, objective, and boundaries of analysis. Collect off-topic themes on a parking lot. | A tight scope produces better results than a complete but diffuse sweep. |
2Collect raw material | 20-40 min | Gather and visualize facts, events, options, constraints, and assumptions. | Keep facts and interpretations separate. Mark uncertain points instead of smoothing them. |
3Build structure | 30-60 min | Fill the isolation map step by step, clarify relationships between elements, and make contradictions visible. | Do not evaluate too early. Stabilize structure first, then derive conclusions. |
4Review and condense | 20-40 min | Mark gaps, weak assumptions, counterexamples, and critical paths. Check output for understandability. | If nobody can explain the logic in two minutes, the artifact is not ready. |
5Define next steps | 15-20 min | Document decision, experiment, test, measure, or follow-up with owner and date. | An excellent artifact without a next action remains knowledge work without impact. |
05
Artifact
What comes out at the end
Form
Isolation Map with occasion, scope, key elements, assumptions, flagged gaps, outcome interpretation, and next step with owner and date.
Versioning / ownership
Save artifact with date, scope, and participants. On new evidence, create a new version or change note so decision logic remains traceable.
Tool alternatives
- Miro or FigJam
- Lucidchart or draw.io
- Confluence or Notion
- Google Docs or Sheets
- Markdown in repository
fault-isolation-working-template.md
Compact working template for Fault Isolation with context, input, output artifacts, and next step.
Fault Isolation Canvas
Context
What is this method used for?
Core question
Which question should be answered at the end?
Input
Which data, observations, or materials are available?
Working area
- Area 1:
- Area 2:
- Area 3:
- Relationships / patterns:
Output artifacts
- Fault Isolation Map:
- Test Log:
- Excluded Hypotheses:
- Narrowed Fault Area:
Open questions
- ...
Next step
Owner, date, and success signal.
06
Example output
Concrete filled scenario, fictional example
fault-isolation-beispiel.md
Concrete filled scenario, fictional example
Fault Isolation - Webhook delivery faulty
Scope: A specific project area is considered, not the entire company. Working question: Which system area most likely causes the symptom, and which tests narrow the fault domain further?
Output excerpt:
- Fact 1: Current observation is documented with source.
- Assumption 1: The key causal chain is plausible but not yet proven.
- Critical point: one open condition decides whether the preferred direction is viable.
Result: The team chooses a focused next step with owner and date. Signal: Move from large fault space to a testable interference area.
07
Pitfalls
Recognize symptoms and steer against them
Trap
Scope drifts
Symptom
New topics are continuously added and artifact loses focus.
What to do
Keep scope visible and park new topics.
Trap
Assumptions become facts
Symptom
Conversation sounds certain despite weak evidence.
What to do
Mark every uncertain statement and set a validation point.
Trap
Too early action
Symptom
Team jumps to measures after only a few minutes.
What to do
Complete structure first, then derive options or actions.
Trap
No negative checks
Symptom
Artifact only confirms favorite hypothesis.
What to do
Explicitly ask for counterexamples, negative branches, or excluded options.
Trap
No owner
Symptom
Result is understandable, but no one carries it forward.
What to do
Document next step with owner, date, and success signal.
08
Stop criteria
Done signals checkable in under a minute
Trigger or scope is not clear.
No raw material or no participants with context knowledge.
Method is used to justify an already failed decision.
Important assumptions cannot be discussed openly.
No owner for result or follow-up is available.
Finished the runsheet?
Go to the profile for purpose, similar methods, and sources or continue to the next method in the catalog.