Technology-enabled airborne spacing and merging

Over the last several decades, advances in airborne and groundside technologies have allowed the air traffic service provider (ATSP) to give safer and more efficient service, reduce workload and frequency congestion, and help accommodate a critically escalating traffic volume. These new technologies have included advanced radar displays, and data and communication automation to name a few. In step with such advances, NASA Langley is developing a precision spacing concept designed to increase runway throughput by enabling the flight crews to manage their inter-arrival spacing from TRACON entry to the runway threshold. This concept is being developed as part of NASA's distributed air/ground traffic management (DAG-TM) project under the Advanced Air Transportation Technologies Program. Precision spacing is enabled by automatic dependent surveillance-broadcast (ADS-B), which provides air-to-air data exchange including position and velocity reports; real-time wind information and other necessary data. On the flight deck, a research prototype system called airborne merging and spacing for terminal arrivals (AMSTAR) processes this information and provides speed guidance to the flight crew to achieve the desired inter-arrival spacing. AMSTAR is designed to support current ATC operations, provide operationally acceptable system-wide increases in approach spacing performance and increase runway throughput through system stability, predictability and precision spacing. This paper describes problems and costs associated with an imprecise arrival flow. It also discusses methods by which air traffic controllers achieve and maintain an optimum inter-arrival interval, and explores means by which AMSTAR can assist in this pursuit. AMSTAR is an extension of NASA's previous work on in-trail spacing that was successfully demonstrated in a flight evaluation at Chicago O'Hare International Airport in September 2002. In addition to providing for precision inter-arrival spacing, AMSTAR provides speed guidance for aircraft on converging routes to safely and smoothly merge onto a common approach. Much consideration has been given to working with operational conditions such as imperfect ADS-B data, wind prediction errors, changing winds, differing aircraft types and wake vortex separation requirements. A series of Monte Carlo simulations are planned for the spring and summer of 2004 at NASA Langley to further study the system behavior and performance under more operationally extreme and varying conditions. This coincides with a human-in-the-loop study to investigate the flight crew interface, workload and acceptability.