GPS Supplemental Navigation Systems for Use During the Transition to a Sole-Means-GPS National Airspace System

The current Federal Radio Navigation Plan presents a plan that includes phasing out of existing radio-navigation aids as part of the transition to sole-means-GPS navigation in the United States. GPS based systems are also being envisioned as becoming the primary means of air traffic control resulting in the retirement of older primary and secondary surveillance radar (SSR) systems. This paper discusses the use of existing radio-navigation aids to provide a redundant navigation system alongside GPS/WAAS during the transition to a sole means GPS national airspace system. Specifically, the paper examines three such systems based on existing equipment such as Distance Measuring Equipment (DME), the Traffic and Collision Avoidance System (TCAS) and LORAN. The predicted performance of these systems can be used to determine the number of the existing radionavigation aids that should be left in place to provide adequate navigation services during the transition to solemeans-GPS navigation.