ABSTRACT
Civil aviation is a vital sector of the U.S. economy. In 2009, air transportation and related industries generated $1.3 trillion and employed 10 million people in the United States (Federal Aviation Administration, 2014). The U.S. National Airspace System (NAS), which provides the infrastructure needed for the operation of civil aviation in the United States, refers to all the hardware, software, and people involved in managing air traffic. At any given moment, as many as 5,000 aircraft may be flying in U.S. skies, and in 2011, the NAS managed the progress of nearly 10 million flights. However, the capacity of the U.S. airspace is limited by the ability of controllers to detect conflicts between aircraft and resolve them in a safe manner when traffic density is high. As a result, the air transportation system often experiences significant delays and lost productivity, and it produces greater amounts of noise pollution, carbon dioxide (CO2), and other greenhouse gas (GHG) emissions than it would if operations were more efficient. In 2005, the Air Transport Association, a group representing airlines, estimated the cost of delays to airlines at $5.9 billion (Borener et al., 2006).
