scope:

This document provides Version Downloadable 7.1 of the TCAS II logic and sets forth the minimum operational performance standards for TCAS II equipment. The main changes are the enhancement of the Resolution Advisory Sense reversal function, and the replacement of "Adjust Vertical Speed, Adjust" Resolution Advisories by "Level Off, Level Off" advisories. Volume I contain the rationale for equipment characteristics, minimum performance standards, bench test procedures, and installed equipment performance. Volume II presents the required collision avoidance algorithms in a state chart formulation with informational commentary text. Attachment A provides both high and low level pseudocode representations of the collision avoidance algorithms. The standards and performance requirements in the document ensure that TCAS II is fully interoperable with other elements and equipment of the National Airspace System.