The NASA Aeronautics Research Institute (NARI) awarded Saab a cooperative agreement to prototype and test a new tool for the optimization of air traffic across multiple phases of operations, including the airport surface and terminal airspace, with more efficient 4-D trajectory solutions. This research project will enable the aviation industry to more precisely develop future solutions for the Next Generation Air Transportation System (NextGen). Saab, along with its partner NextGen Aerosciences (NGA), will apply two separate techniques (NGA's Continuous Replanning Engine and Probabilistic Graphical Models) to address optimal 4-D (three spatial dimensions plus time) flight. In addition, the research will examine how rapidly changing situations will impact operations and how to more effectively address uncertainty in future operations. The study will focus on managing traffic in the highly congested and complex New York airspace and on the surface at four busy airports in the New York City area that form a metroplex, (a group of proximal airports whose arrival and departure operations are highly interdependent). Currently, controllers at the airports and in the New York TRACON implement a wide variety of traffic management strategies to manage the airspace and surface traffic interactions. These strategies—which include miles-in-trail restrictions, surface holds for TRACON approval, and indirect routings—contribute to delays and additional fuel consumption. The proposed research aims to alleviate such adverse effects of the metroplex interactions on air traffic.