2005 Volume 113 Pages 99-106
In the surveillance of aircraft using Automatic Dependent Surveillance (ADS), the extrapolated positions need to be estimated from the position data received from each aircraft and to be shown on a display. The extrapolation errors affect surveillance accuracy. The author has evaluated the extrapolation errors in α-βtracking for ADS and clarified the characteristics of extrapolation errors when the aircraft position data are used to estimate most likely positions so far. In ADS, the velocity and track angle of aircraft can also be transmitted together with positions at need. This paper describes the extrapolation errors in α-β tracking using velocity and track angles as well as aircraft positions. We confirmed through simulations and theoretical analysis that the use of velocity and track angles improves the extrapolation accuracy for all values of α and that the improvement is more remarkable as α decreases. For example, while the extrapolation error in conventional α-β tracking is about 1.3km for α=0.5 for a turn angle of 90°, it reduces to about 0.1km by using velocity and track angles (velocity is between 150kt and 200kt, ADS reporting interval is 10 seconds).
