FTA is an event-oriented analysis technique, which means that it allows for the consideration of hardware failures and other undesirable events, such as software failures, human errors, operation and maintenance errors, and environmental influences. It offers a simple and powerful approach for reliability and safety analysis. FTA is a deductive, top-down approach that begins with a single event to be analyzed, usually an undesirable or catastrophic failure, and then aids in the process of determining the specific causes that can lead to the occurrence of this event.

FTA is based on a simple set of rules and logic symbols (such as AND gates, OR gates, and many others) from probability theory and Boolean algebra. It consists of generating a logic model that allows for both qualitative and quantitative evaluation of system reliability or availability.

A fault tree is a pictorial representation of the events that could lead to an undesired event in the system. From a qualitative perspective, you can generate minimal cut sets, which are the smallest sets of events, such that if they all occur, cause the undesired top-level event to occur. From a quantitative perspective, you can determine the likelihood of occurrence of the top event and any intermediate events given the necessary probabilities of the contributing lower-level events.

If you are unfamiliar with FTA and would like to learn morel, the following selections are excellent references: