NASA has been a leader in most technologies it has employed in its programs over the years. One of the important NASA objectives is now to add Probabilistic Risk Assessment (PRA) to its repertoire of expertise in proven methods to reduce technological and programmatic risk. Fault Tree Analysis (FTA) is one of the most important logic and probabilistic techniques used in PRA and system reliability assessment today. The current Fault Tree Handbook, serves two purposes: • As a companion document to the training material taught in FTA courses for practicing system analysts, and • To assist aerospace FTA practitioners in acquiring and implementing current state-of-the art FTA techniques in their applications.