Including Systematic Faults into Fault Tree Analysis

Abstract

Fault Tree Analysis (FTA) is a technique widely used for fault forecasting of physical systems. Although FTA is considered a well established safety analysis technique, paradoxically classical Fault Trees include only random faults. However, in modern automated systems, undesirable events arise not only from random hardware faults but also from defects in the logic of software controllers that control the physical system. Faults generated by these software controllers are systematic faults caused by coding errors or misinterpretations of control requirements. This paper proposes an extension to the basic Fault Trees construction process which takes into account this category of faults and advocates the use of dynamic and temporal gates to model it.