Fault Tree

FAULT TREE

What Is It

A fault tree is a model that logically and graphically represents the various combinations of possible events, both faulty and normal, occurring in a system that leads to the top undesired event. It uses a tree to show the cause-and-effect relationships between a single, undesired event and the various contributing causes using standard logic symbols to connect the branches of the tree. In risk management, fault tree could be applied to identify potential conditions, or a combination of conditions, that could cause the risk. The sequences of conditions, or pathways, will be used to analyze the predetermined risk. The branches of the tree, the cause-and-effect relationships, will be used to analyze the top undesired event or the predetermined risk.

When To Use

Use Fault Tree

To identify numerous potential conditions which lead to a risk, especially to a very high risk.
To analyze complex multi-dimensional system.
To determine the predetermined event (risk) probability by propagating probabilities throughout the failure pathway of the event.

Benefits

This method

Helps to answer the question what can go wrong?
Identifies main paths to disaster and potential single point failures to provide risk mitigation guidance.
Breaks down activities into detailed steps for better management.
Graphically displays the chain of conditions leading to the predetermined risk.
Results in improved understanding of system characteristics and detailed assessment of system "common cause" vulnerability.