EUROCAE ED‐275 VOL 2 PDF

This document assumes the reader is familiar with ACAS Xu including planned variants of the system software and its modular breakdown. If not, the reader is encouraged to review the ACAS Xu Concept of Operations (ACAS Xu CONOPS) [4].

The ACAS X algorithmdesign consists of two separatemodules: (1) the Surveillance and Tracking Module (STM), which detects aircraft in the vicinity and tracks their position, and (2) the Threat Resolution Module (TRM), which identifies threats and provides resolution guidance. The TRM consists of two modules: (1) the vertical TRM, which produces climb and descend advisories, and (2) the horizontal TRM, which produces right and left turn advisories. The algorithms in this ADD are limited to ACAS Xu, the variant of ACAS X intended for installation on unmanned aircraft. This document contains modifications informed by operational suitability and performance evaluations conducted via modeling and simulation as well as analysis of flight tests.

Although this document provides justification for certain aspects of the TRM algorithms, it is not intended to overview the analyses that contributed to the various design decisions. This document does not discuss the process of optimizing the lookup tables. For such details, see [9].

Purpose

This document provides the AlgorithmDesignDescription (ADD) for the Surveillance and Tracking Module (STM) and the Threat Resolution Module (TRM) of the next generation Airborne Collision Avoidance System (ACAS X). The algorithms are described at a sufficiently high level to allow for implementation in a variety of software languages and hardware platforms, thereby providing maximumfreedom tomanufacturers while ensuring the intended output fromthe system. This document provides descriptions of the algorithm’s operations. Every effort has been made to ensure the accuracy of this text, however, in case of a conflict between the description and the function of the algorithm, the algorithm function is correct.