The Percentile Analysis of Guidance System Errors

The preferred method for the measurement or specification of guidance system errors is the percentile grouping, which states that a predetermined miss distance is not exceeded by a certain percentage of the data. The percentage to be used is a function of the tradeoff between the costs of constructing and testing the systems versus the costs associated with missing the target area. Advantages of this method include immunity to variations in the error model, immunity to the effects of occasional bad data points, simplicity of analysis, and proper appraisal of guidance system requirements. Methods for combining percentile specifications of orthogonal components and of additive errors of guidance systems are derived, which indicate that the error analysis of a guidance system can be formulated without requiring detailed knowledge of the nature of the error distribution.