TIPS FOR BUILDING GOOD WHY TREES

TIPS FOR BUILDING GOOD WHY TREES

• TIPS FOR BUILDING GOOD WHY TREES
• IS THE CAUSE and EFFECT TRUE?

TIPS FOR BUILDING GOOD WHY TREES

• TIPS FOR BUILDING GOOD WHY TREES

• Intangible Cause
• Tangible Effect

TIPS FOR BUILDING GOOD WHY TREES

• TIPS FOR BUILDING GOOD WHY TREES

• Experience shows you should drive at least five (5) levels (5 times) to get to operating system key factor (S)

• WHY

• WHY

• WHY

• WHY

• WHY

• FAILURE EVENT

• KEY FACTORS

• Physical Causes

• Human Causes

• System Causes

• HOW MANY TIMES DO YOU ASK WHY?

WHEN BUILDING A WHY TREE

• WHEN BUILDING A WHY TREE
• When You find the Root Key Factor(s) at the
• Operating System,
• OR
• At the point where you no longer have control or
• influence over the solution.
• There are certain things you have neither control nor influence over. Forget about them, or get the appropriate person(s) to deal with them.
• An example is the 35A and the 50A fuses in the WHY Tree example, which are manufactured nearly alike.

HOW LONG DOES IT TAKE TO COMPLETE A WHY TREE

• HOW LONG DOES IT TAKE TO COMPLETE A WHY TREE
• Depends on the complexity of incident and number of observations or "branches" to be processed.
• Consider breaking "WHY Tree" sessions down into segments to maintain group focus and energy.
• Two hour segments recommended.
• Verification activities should occur between sessions with report back.
• Don't rush the process - sacrifice quality of investigation and ultimately the findings / improvements.