A letter report issued by the Government Accountability Office with an abstract that begins "The Federal Aviation Administration (FAA) predicts that the national airspace system will become increasingly congested over time, imposing costs of delay on passengers and regions. While transforming the current air-traffic control system to the Next Generation Air Transportation System (NextGen) may provide additional en route capacity, many airports will still face constraints at their runways and terminals. In light of these forecasts, the Government Accountability Office (GAO) was asked to evaluate regional airport planning in metropolitan regions with congested airports. GAO (1) identified which airports are currently or will be significantly congested and the potential benefits of regional airport planning, (2) assessed how regions with congested airports use regional airport planning in decision making, and (3) identified factors that hinder or aid in the development and implementation of regional airport plans. GAO reviewed studies; interviewed FAA, airport, and other aviation and transportation officials; and conducted case studies in selected regions."