Risk forecasting using heritage-based surrogate data

While an individual failure analysis approach has been recommended for the space shuttle program, [Gehman, HW, Jr et al., August 2003] other more heuristic and far simpler approaches have also been used in the past to provide useful information to decision-makers when failure data is scant. This paper provides an example of visual mapping using heritage data might be used to discover problems in complex systems before they lead to failure, using the Saturn launcher family as an example. An effort will be undertaken to further analyze the available data in an attempt to answer the question: "What would have been the risk of future launches if the Saturn launcher had continued in service?" The motivation is to try to show how the use of heritage data, when properly adjusted for growth and combined with scant data on the program under investigation produces estimates consistent with the use of properly analyzed precursor data. Further, an investigation was conducted as to whether heritage and precursor studies can provide considerably better insight than scant failure data alone. On the basis of the findings, it is suggested that heritage and precursor estimates may be more realistic and consistent with launcher history than the more optimistic estimates produced from traditional bottom-up approaches.