Airborne TIS-B to TIS-B track correlation for reduction of Cockpit Display shadows

During development of revised international standards for the Aircraft Surveillance Applications (ASA) System RTCA Special Committee 186 Working Group 4 (SC-186 WG4) learned of operational cases of Traffic Information Service - Broadcast (TIS-B) track identifier changes (i.e., a discontinuity) across en route service volume boundaries. If not modified the preceding standards for airborne surveillance processors would allow generation of multiple coexisting airborne tracks for individual aircraft and corresponding symbols (graphical representations of these tracks) on cockpit traffic displays. Analysis and characterization of operational data indicated that up to three TIS-B tracks with different identifiers could be generated for a single aircraft within a short time period (e.g., 30 seconds). A high fidelity simulation of the ASA system (airborne processor and display) was used to show that during periods of track coexistence significant display symbol shadowing and divergence could occur. These characteristics, especially when pertaining to multiple aircraft within range of ownship, posed a potential problem of misleading information being presented to flight crews. RTCA SC-186 WG4 determined that a new function, intra-source TIS-B to TIS-B track correlation, was required for airborne surveillance processors. In support of this decision, the MITRE Corporation's Center for Advanced Aviation System Development (CAASD) developed algorithms for this function that instantaneously detect TIS-B track identifier changes and suppress display shadows to ensure flight crew perception of track continuity. This paper describes the analysis and characterization of the problem, development of an airborne algorithmic solution, formulation of strenuous test cases based on operational data, simulation of the TIS-B to TIS-B correlation function, and evaluation of its performance.