Evaluation of aircraft separations observed in radar data of terminal operations

The advent of satellite-based surveillance technologies including automatic dependent surveillance - broadcast (ADS-B) as well as the transition to a performance-based National Airspace System (NAS) are expected to result in improved ATC surveillance accuracy and aircraft navigational precision. Within the framework of the Next Generation Air Transportation System (NextGen), this evolution is envisioned to pave the way for reduced separation minima as a beneficial way to improve airspace capacity and operational efficiency. The development, approval, and validation of reduced separation standards that safely support future capacity gains require quantitative information of aircraft separations applied in actual operations that reflect the entirety of operational factors. This paper outlines the analysis capabilities developed for NAS-wide evaluations of aircraft separations observed in ATC surveillance data. It describes the analysis approach taken to enable quantitative comparisons and presents examples of evaluation results of terminal radar data recorded at key United States (US) airports. The comparisons illustrate characteristics of aircraft separations found in actual terminal operations and identify separation signatures that pinpoint geographic areas and altitudes where separation standards represent the most significant operational constraints.