Aircraft Tracking using
GPS Position and Velocity Reports

Ran Gazit

Department of Aeronautics and Astronautics
Stanford University

ABSTRACT

A new approach to Air Traffic Control (ATC) calls for every aircraft to periodically broadcast its GPS derived position. The position reports will be received by ATC controllers, and will be used for aircraft tracking and conflict prediction. This technique is expected to increase the quality and extent of ATC surveillance coverage, and to provide a highly accurate Collision Avoidance System.

In this study we identify the required elements of the appropriate tracking algorithms, and estimate the improvement in tracking accuracy that can be obtained by using this technique. A measurement error model that matches the correlation functions of both position and velocity errors is identified. This model is combined with two aircraft models in an adaptive Kalman filter. A switching logic provides the best position and velocity estimates during all phases of flight, and guarantees smooth transition of the estimates during satellite constellation changes.

The filter performance is checked in a Monte Carlo simulation, using real GPS data and simulated aircraft motion. The simulation includes the effect of an imperfect radio data link due to message interference. The tracking accuracy is then compared to the performance of modern ATC radar trackers. The effect of the improved surveillance accuracy on minimum separation standards is demonstrated.

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