This session will consider the implementation of increasingly efficient ICAO separation minima in the en-route phase of flight. This work has provided demonstrable and measurable benefits to the aviation industry and has been enabled by the expansion of ATS surveillance services into airspace that was previously the domain of procedural separations and enabled by CNS capabilities (such as CPDLC, ADS-C and SB ADS-B) which have provided the foundation for performance-based (RCP, RNP, and RSP) separation minima.