The TCAS algorithms are part of the spec designed by RTCA (Radio Technical Commision for Aeronautics) Inc for the aviation community. They are a non profit organisation that includes roughly 250 government, industry and academic organisations from the United States and around the world. Together they work on CNS/ATM issues and standards.
You can buy the TCAS specifications and algorithms by looking up the appropriate document and then sending lots of money to them
http://www.rtca.org/downloads/doclist.htm#_Toc79999068
DO-185A is the document you probably want (for TCAS II).
DO-185A, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance System II (TCAS II) Airborne Equipment
Issued 12-16-97 s Prepared by SC-147
This document provides Version Downloadable 7.0 of the TCAS II logic and sets forth the minimum operational perfor_mance standards for TCAS II equipment. Among the changes, this Version Downloadable improves the system's surveillance performance and modifies the interference limiting algorithms to account for aircraft densities near airports as well as to permit longer range surveillance. Improvements have been made in tracking Mode S targets and in permitting TCAS to receive the extended Mode S squitter. To preclude repeatedly issuing Traffic Advisories (TA) against the same target, changes have been made to ensure that a target's TA status is maintained in slow closure situations by using more stringent drop criteria. Other changes include credibility checks to ensure integrity of the data being supplied to the collision avoidance logic and additional, more thorough tests for installed equipment.
Volume I contains the rationale for equipment characteristics, minimum performance standards, bench test proce_dures, 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.
Note:
TSO-C119b -Requests for a Copy of the CD-ROM Titled “TSO C119B Changes to DO-185A, Approved by
SC-147 RWG* dated December 4, 1998 should be directed to: Federal Aviation Administration, Headquarters, Technical Programs & Continued Airworthiness Branch (AIR-120), (P) 202-267-9578.
Available in CD Format ONLY
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