The Impact of Policy on System Reliability

Examples taken from observations of current military maintenance experience show how reliability is affected by the paperwork and procedures which surround a system´s use. Information theory is used as a measuring device to demonstrate the degree to which system performance is not a function of engineering design. In the case studied (the Air Force´s F-106 avionics systems in use), many reported failures were not the result of either faulty design or human error, but were rather ``required´´ by the procedural environment. Information theory provides a means of measuring the size of this effect. Furthermore, information theory in this kind of application may be useful in sorting out the relative importance of the various factors which influence variation in system performance.