Being as safe as reasonably practicable (ASARP) is a fundamental principle of adequate safety at NASA. As discussed in the NASA System Safety Handbook, the ASARP region of a trade space contains those alternatives whose safety performance is as high as can be achieved without resulting in intolerable performance in one or more of the other domains. In practice, however, identifying an ASARP alternative from some set of alternatives is challenging, since on the one hand the concept of ASARP is based on safety being incommensurable with other objectives, while on the other hand any solution that puts people at risk implies some valuation, stated or not, of human life. In many industries, an explicit valuation of human life is made, and standard decision analysis is conducted, with a goal of maximizing expected utility. Unfortunately, this approach is antithetical to the ASARP principle.

This paper presents a simple expected-utility approach to identifying an ASARP alternative that does not depend on an a priori valuation of human life and which is conceptually faithful to the incommensurability of safety. It is based on inverting the expected utility equation to ask, “What is the most value that can be put at risk on a mission and still be worth it?”