the system defect discovery process. Ignoring this information will likely produce much less predictive models than the approaches available today that model this process. Fourth, methods exist and are currently used for developing early assessments of system reliability that make full use of the disparate information available in industrial applications (e.g., information derived from maintenance records, computer simulations, expert knowledge, historical data, and test data, and information from similar systems, or systems with similar parts, components, or processes). However, these methods are not currently applied to defense systems (with a few notable exceptions). Finally, when determining total time on test (in operational test) or other aspects governing an operational test design, requisites for testing system effectiveness typically have been the dominant consideration, while the requisites for producing assessments of operational suitability have received considerably less weight.

The above five areas are ones in which greater attention to reliability measurement, reliability modeling and data collection, and the management of defense system reliability could prove beneficial. Two specific approaches to reliability growth management were considered at the workshop, as summarized below.

The Booker Paper

It is currently typical for reliability assessment of defense systems to be used primarily as input into the DoD acquisition milestone process, for deciding whether a system in development can proceed to the next milestone. Since operational testing is carried out near the end of the second phase of system development (known as engineering and manufacturing development), there is little or no opportunity for reliability assessment of a system’s operational performance to inform system design during its early stages. In contrast, in various industrial applications of system development, reliability assessment has an earlier and more continuous influence on system design. A major benefit of this early influence is that, generally speaking, the earlier modifications are made to system design, the less costly those modifications are. Further, the better a system design is, the more likely it is that the system will pass operational test on its first attempt. Finally, and most important, the better the system design is, the more likely it is that the system ultimately approved for full-rate production will perform better and be less costly to operate in the field, since it will likely require less maintenance and repair. Changing the role of reliability assess-

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement