In this chapter, an overview of the fifth ENRI International Workshop on ATM/CNS (EIWAC2017) is provided, together with summaries of presentations at keynote sessions and special speeches. This chapter also explains the approach of the Electronic Navigation Research Institute toward the organization of EIWAC. In this workshop, various aspects of air traffic management (ATM) and its enablers in the fields of communication, navigation, and surveillance (CNS) were discussed. EIWAC2017 was held in Nakano, Tokyo, from November 14 to 16, 2017.