Description / Abstract: DO-298 is an SC-147 report which documents analyses recommending changes to the TCAS II Version 7 collision avoidance logic (Section 2.0 item 2) in accordance with SC-147 Terms of Reference guidance. June 2014 RTCA List of Available Documents Page 46 of 142 The report was developed to perform a detailed analysis of the TCAS II Version 7 Resolution Advisory (RA) sense reversal logic, investigating the safety impacts of revising the collision avoidance logic to improve the performance of RA reversals for certain encounter geometries. Some encounter geometries have been shown to exist which TCAS II Version 7 may not appropriately resolve with RA sense reversals in certain airspaces. SC-147 has studied the frequency with which these geometries are operationally experienced and recommends the changes specified in this report to reduce collision risk in these encounter geometries.