Lincoln Laboratory Evaluation of TCAS II Version 7: Volume I

This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in the U. S. airspace. Version 7 is a major revision to the TCAS II logic consisting of more than 300 separately defined changes affecting all major TCAS areas (surveillance, CAS logic and displayslaurals). Lincoln Laboratory evaluated the logic by examining approximately two million simulated pain&e TCAS-TCAS encounters, derived from actual tracks recorded in U. S. airspace. The main goals of the evaluation were: (1) to study the performance of the new TCAS-TCAS coordinated reversal logic; (2) to detect and explain any areas of poor performance; (3) to examine the performance of the version 7 logic for the 30 Representative NMACs identified during the 6.04a logic evaluation; and (4) to understand the limitations of the logic by analyzing every version 7 NMAC. Five Lincoln Laboratory analysis programs written for previous logic evaluation work were updated and new software was written to aid in the evaluation of TCAS-TCAS sense reversals. There were four phases of the evaluation corresponding to the above goals. For each phase the report gives an overview of the evaluation approach taken and a description of the results. An overall summary and perspective on the evolution of the TCAS II logic are given at the end of the report. This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7. BACKGROUND TCAS II is an airborne collision avoidance system required since December 1993 by the Federal Aviation Administration (FAA) on all air carrier aircraft with more than 30 seats operating in the United States airspace. The FAA mandated the current TCAS II logic version 6.04a by December 1994 in order to correct a potential safety problem in earlier versions of the TCAS II logic. Version 7, also known as Change 7, is a major revision to the 6.04a logic. It provides enhancements to all major TCAS areas (surveillance, Collision Avoidance System (CAS) logic, and displays/aurals) and is essentially …