Probability of Raid Annihilation, P RA , is the Navy's 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. Threat performance and combat system performance both can vary significantly with natural environment conditions so the P RA federation incorporates these effects. In an earlier paper (01F-SIW-077), uncertainty in the P RA Measure or federation outcome was linked mathematically to uncertainty in the implemented natural environment representation. This procedure was based on the detailed documentation and analysis provided by the P RA Environment Concept Model (ECM). In this paper uncertainty results are presented using this procedure. The uncertainty assessment includes a reasonable range of uncertainties in the individual environment parameters but maintains consistency within the environment representation by means of the ECM.Maintaining consistency is required because the uncertainty analysis shows that the uncertainty in P RA Measure depends not only on the magnitude of uncertainty in an environment parameter but also on the overall environment representation supplied. The uncertainty analysis not only provides an assessment of how good the P RA Measure is but also provides information on the best-cost benefit to improvement in the P RA measure.