Description / Abstract: This document examines operational and technical performance issues observed in the current TCAS II as well as issues anticipated to emerge in the future as NextGen changes affect the airspace. It explores potential changes to address these issues and addresses their maturity. The document comments on additional research and development that would be required, either to better characterize the issue, to develop solutions or both.

Both issues and solutions are presented in two major categories: Issues affecting the current TCAS II and changes that could be made to that system without substantial redesign. These are termed "near-term" changes, but their development, certification and implementation could take as long as six years. Issues anticipated in the future, and changes that would require either substantial redesign or that might use entirely new sources of surveillance data. These changes are termed "far-term" and would take more than 10 years. Some far- term solutions may be required to address near-term issues. The document presents tables to help the reader map solutions to issues and recommendations are presented for the solutions deemed most promising and deserving of high research priority.