Revision Accommodates Changes To TCAS V7.1

The FAA has released an Advisory Circular (AC) to provide applicants with guidance for obtaining an airworthiness approval for traffic alert collision avoidance systems II (TCAS II). It also provides guidance for certification of a stand-alone Mode S transponder system.

The AC includes the TCAS II versions 7.0 and 7.1 along with the latest iteration, which is version 7.1 containing hybrid surveillance functionality as defined by TSO-C119d.

The AC was written "to guide applicants seeking airworthiness approval for TCAS II version 7.1 (V7.1) that are certified to technical standard order (TSO) C119c or TSO-C119d, Traffic Alert and Collision Avoidance System (TCAS) Airborne Equipment, TCAS II with Hybrid Surveillance. Guidance is also provided for those applicants seeking airworthiness approval for stand-alone Mode S transponders that are certified to TSO-C112d, Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment. The guidance presented in this AC can also be used for those seeking airworthiness approval for TCAS II version 7.0 (V7.0) that are certified to TSO-C119b, Traffic Alert and Collision Avoidance System (TCAS) Airborne Equipment, TCAS II."

The AC is not mandatory, the FAA says, and is not to be considered a regulation. The AC has been revised to accommodate the changes of TCAS V7.1, incorporate lessons learned since the last revision to the AC, and add policy for the hybrid surveillance functionality. The most significant change associated with the latest iteration of the TCAS II TSO Standard, TSO-C119d, is the requirement to incorporate RTCA/DO-300A Hybrid Surveillance functionality. This requirement has been added principally as a means of reducing congestion on the 1090 Mhz frequency while airborne and when on the ground.

FMI: Advisory Circular