As an engineering discipline System Safety Engineering is relatively new, with an origin in the 1960s. During the last 60 years the management approaches used by the discipline have evolved and six discrete ideas have come to the fore which can be characterized as phases or eras. The newer ideas have been implemented successfully by a few organizations whereas the larger government sponsored system safety programs within DOD, NASA and DOT for the most part remain using methods developed in the earlier eras. This paper describes the six eras, identifies their distinguishing features, and points to best practice documents which embrace and define each era.
