Fault Tree Analysis (FTA)

The Fault Tree Analysis technique was developed by H.R. Watson of Bell Telephone Laboratories in 1962. FTA was first applied to anti-ballistic systems. Boeing further developed and refined the process becoming the foremost proponents of the method.

It is an accepted technique used to analyze system safety. Hardware, software and human factors can be analyzed in an integrated fashion. FTA is particularly suited to the analysis of complex systems consisting of several functionally related or dependent subsystems with different performance objectives. This is especially true whenever the system design requires the collaboration of many specialized technical design groups.

A fault tree is a symbolic logic diagram, in the form of an inverted tree, showing the cause and effect relationship between an undesired event and contributing causes. Fault trees clearly show the parallel and sequential combinations of events that can constitute a hazard. FTA always begins assuming that an undesired event has taken place. It is a backward moving process which attempts to determine all possible causes for the undesired event to occur.

FTA can imply different things to different people as reflected by the wide range of depths of analysis that exist. Coverage in the areas of:

• fault tree verification,
• minimal cut set analysis,
• common cause analysis,
• importance analysis, and
• supporting material

varies dramatically as does fault tree quality. There truly are some scary FTA's out there! A military client of ours showed us a SAR produced by a well-known defense company. We noticed a problem at the first gate in the tree!

HCRQ has over 20 years experience in FTA and we can teach you how to perform one the right way. We punch holes in other's fault trees every day.

Do you know the 17 ways that distinguish a "good" fault tree from a "bad" one?

Do you know the disadvantages of using FTA?

HCRQ is equipped with CAFTA and Item Fault Tree software.