A fault tree analysis (FTA) is a logical, graphical diagram that starts with an unwanted, undesirable, or anomalous state of a system. The diagram then lays out the many possible faults, and combinations of faults, within the subsystems, components, assemblies, software, and parts comprising the system that may lead to the top-level unwanted fault condition.

An FTA shows the many possible cause-and-effect paths to a specific fault condition. For example, a laptop computer may have a top-level fault of not turning on. A few possible causes are a dead battery, faulty power distribution circuitry, or a broken power switch.

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