TCAS (Traffic Alert and Collision Avoidance System) is a specific implementation of the ACAS (Airborne Collision voidance System) concept. TCAS II version 7.0 is currently the only available equipment that is fully compliant with the ACAS II Standards and Recommended Practices (SARPs). ACAS II provides “Resolution Advisories” (RA’s) in the vertical sense (direction) advising the pilot how to regulate or adjust his vertical speed so as to avoid a collision.