On the airworthiness approval of a SAR ATR system

Abstract

A manned platform is to be equipped with a Synthetic Aperture Radar (SAR) based Automatic Target Recognition (ATR) system for precision targeting. The platform's airworthiness has to be approved including the ATR system, i.e. the ATR system needs to be qualified appropriately. Part of the airworthiness approval is a hazard analysis. In general, this is carried out to make sure that the probability of a fatal error in one hour of flight is 10^-9 or lower. To date, error probabilities of a SAR-based ATR system, i.e. error probabilities of detection and classification, must be assumed to lie above 10^-9 per hour. This is one reason why existing rules of engagement demand "Man-in-the loop", i.e. to display the result of the ATR system to the pilot. Components to the ATR system are consequently a Synthetic Aperture Radar (SAR) sensor an Automatic Target Recognition (ATR) SAR image processing unit, and a Human Machine Interface (HMI) to the pilot. The aim of the work reported in this contribution was to identify those performance features of the thus defined ATR system that are relevant to airworthiness approval, and to define the procedures to determine the feature values. The paper contains the analysis of a reference case of an airworthiness-approved technical system with an error probability above 10^-9 per hour and a result display to the pilot. In the light of the analysis results, it concludes with an outlook to the airworthiness approval of the ATR system.