Use of aircraft-derived data to assist in ATC tracking systems. Part 2: Some practical tracking filters

At present, aircraft tracks for ATC purposes are formed by filtering SSR data measurements only, but the introduction of selectively addressed systems such as ASDEL and DABS will make it possible to transmit additional on-board measurements to the ground station. This information may be used to significantly improve the tracking performance, and Part 1 of the paper considered the question of the measurement accuracy required and the mechanism by which it may be incorporated into the tracking algorithm. Whereas Part 1 considered the extended Kalman filter as a reference against which to compare other sub-optimal filters, Part 2 considers practical filters, incorporating aircraft-derived data, which are considerably more economical than this reference, and which, in the typical ATC environment studied, gave almost identical results.