Terminal Sequencing and Spacing (TSS): This alternative has been identified as a key capability to address the gap that exists in enabling the use of Performance Based Navigation (PBN) by the Federal Aviation Administration (FAA). This capability leverages Traffic Based Flow Management (TBFM), a system that provides an absolute schedule and displays key information to controllers. Greater detail about this alternative was provided above in the gap analysis.
Relative Position Indicator(RPI): It is a passive situational awareness tool and does not issue advisories. It offers foresight into possible merge issues while relying on the controller to use speed control to achieve sequencing of aircraft. Greater detail about this alternative was provided above in the gap analysis.
TSS Lite & RPI: This is a proposed alternative for the sake of this alternatives analysis. This provides a “hybrid” option which has the potential to provide a great deal of benefit in enabling the use of PBN. While this alternative has not been researched independently it utilizes pieces of information that have been assessed. This option includes the RPI capability as well as two key pieces of information from TSS – runway assignment and sequence numbers. These two tools out of the TSS toolset have proven to provide benefit to controllers as individual pieces of information. This hybrid allows the controller to realize more benefit by adding some of the TSS information without having to be at a facility where TBFM is implemented.
The table below provides a simplistic comparison of the tools listed above.