The Development of the ATC Radar Beacon System: Past, Present, and Future

Absrruct-The ATC radar beacon system is a descendant, through an extended evolutionary development, of military identification friend or foe (IFF) systems begun during World War 11. It is today’s primary source of surveillance data for air traffic control and performs this function with a high degree of effectiveness. A number of programs are underway to correct its current deficiencies. Looking to the future, the further automation of air traffic control together with the projected growth of air traffic lead to requirements for improved surveillime and communication capability. A discreteaddress mode of beacon system operation, with integral ground-airground data link, is under development to meet these needs. HE MISSION of the air traffic control (ATC) system is to maintain separation between aircraft for which it is responsible. Accurate and continuous knowledge of aircraft position is essential to the efficient functioning of the ATC process. As the demands on the ATC system, both in terms of the numbers of users of the airspace and the performance of the aircraft, have steadily increased over the past three decades, techniques for acquiring the necessary position data have been continuously improved. Prior to 1950 civil ATC was based entirely on voice position reports from aircraft as they passed over the radio fixes that defined the airways system. In the early 1950’s radar began to be used to provide the air traffic controller with an independent (of the aircraft) means of monitoring aircraft position. Beginning in the late 19503, an interiogatorltransponder system was added to the radars; this system, the air traffic control radar beacon system (ATCRBS), has become the primary means of air traffic surveillance, with the radars to which it was added assuming a backup role. The ATC surveillance capability must continue to evolve to meet the projected demands of the coming decades. However, as improvements are made, or new techniques introduced, they must be brought “on line” in such a way that there is no degradation or interruption in service during the transition. Sections 11-IV of this paper review the development of ATCRBS, and discuss the performance and limitations of today’s system. Sections V and VI address the improvements needed to meet projected future demands and describe the program under way to develop a discrete-address beacon system (DABS) as an evolutionary upgrading of today’s system.