This algorithm carries out the association of radar measurements ("returns") from different sites and provides, with the IMM estimator, the best estimates of the trajectories of all aircraft in the surveillance region.
The illustration shows the air traffic over a period of 20 min. in the Syracuse, NY, area, based on the FAA radar data from Remsen and Dansville. Note the test flight trajectory with sharp turns just North of Syracuse (in the center of the map).