Evaluation of a Projection Algorithm for the Stereographic Representation of Aircraft in an Air Traffic Control System

摘要

In an air traffic control system such as the National Airspace System (NAS) horizontal control is effected from a ground facility through the separation of aircraft in at least one of the dimensions of latitude and longitude. Ideally, these dimensions are obtained indirectly in real time by means of a projection algorithm that maps raw surveillance information into the stereographic representation of aircraft latitude and longitude on a plane surface. In practice, there is always some processing delay and some difference between the algorithm output and the actual stereographic representation of aircraft position. In addition, the accuracy is affected by the orientation of the plane relative to the control jurisdiction of the facility. While the projection algorithm currently employed in NAS is capable of timely delivery of output due to its structural simplicity, it cannot meet the accuracy requirement of the Advanced Automation System. The accuracy of a simple modification of the NAS algorithm that does meet this requirement is evaluated by means of a technique that avoids determination of the geometric relationship of the plane and the control jurisdiction.