Gamma process based optimal mission abort policy.

• Developing degradation-based and duration-based mission abort policies based on a two-stage degradation process. • Deriving mission reliability and system survivability under the proposed stochastic failure process and mission abort policies. • Investigating the optimal mission abort policies balancing the tradeoff between mission reliability and system survivability. • Providing a detailed comparison of the cost-saving performance of the two proposed abort policies numerically. Various safety-critical systems such as aircrafts, submarines and space stations are required to perform missions continually in harsh environment. To enhance the survivability of such systems, a mission can be aborted when the mission completion becomes problematic and a rescue procedure is immediately initiated. This paper investigates the optimal mission abort policy based on a two-stage Gamma process which can be separated into normal and defective stages. Degradation-based abort policy where a mission is aborted if the system degradation level is higher than a threshold and duration-based abort policy where a mission is aborted if the duration in defective stage is larger than a threshold are considered. The mission success probability and system survivability under these two policies are evaluated and the optimal mission abort thresholds balancing the tradeoff between the mission success probability and system survivability are investigated. A numerical example on an unmanned aerial vehicle (UAV) is presented to illustrate the applicability of the proposed abort policies. [ABSTRACT FROM AUTHOR]