Assessing Uncertainties in the Probability of Raid Annihilation

Abstract

Abstract : The Probability of Raid Annihilation, PRA, is the measure of a single ship with its combat systems to detect, control, engage and defeat a specified raid of threats within a specified level of probability in an operational environment. The Navy, led by Program Executive Office for Theater Surface Combatants (PEO TSC), is developing an assessment process for PRA that uses an innovative combination of live testing and a simulation, the PRA Federation. A crucial element in the assessment process is identifying the uncertainties in the PRA measure, in particular those associated with the natural environment. The PRA Federation is unusual in that a given threat reacts to the combined ship defenses while all ship defenses simultaneously see the common threat. This complexity of interactions with the associated environmental effects makes it very difficult to determine uncertainties in the PRA due to environmental considerations. To further complicate matters, the PRA Federation is designed to permit the interchange between operational and test scenarios, thereby supplementing live testing with simulation results. This interchange capability demands that the relation between the real world and implemented environment be captured in detail so that resulting uncertainties in the PRA due to the environment can be well-understood and documented. Using the PRA measure as a specific example, this paper illustrates a new technique in evaluating how the outcome of simulations is affected by uncertainties in the natural environment provided. The Environment Concept Model (ECM) process, developed under the Navy MARitime Environmental Data Standards (MARVEDS) program for use in developing environmental requirements, is applied to identify and document the complexities within the PRA Federation and the links with the operational and test environments.