Mosaic ATM proposes to study a Relative Position Indicator (RPI) concept for managing mixed RNAV and traditionally vectored arrival traffic, to enable increased adoption of RNAV procedures in airspace or traffic environments that include mixed RNAV and non-RNAV aircraft. The most common reason controllers give for why RNAV procedures are not used at their airports is the difficulty handling mixed RNAV and non-RNAV flights. Our proposed concept directly addresses this complaint, providing a controller decision aid to help controllers merge RNAV and non-RNAV aircraft. We will also study other applications of the RPI concept, such as planning departure slots into an arrival stream. The project directly compliments NASA's research and contributes to the NASA Airspace Systems Program's mission. The results of this project could be applied within NASA's TAPSS project to address mixed RNAV/vectored aircraft environments. Since RPI technology has been deployed by the FAA for other applications, and the project addresses a current need, the project also endeavors to transfer the resulting technology to the FAA for operational use.