The Airport Capacity Enhancement Plan plays a major role in the Federal Aviation Administration's (FAA) effort to increase airport capacity and efficiency without compromising the safety of passengers or the environment. The Plan identifies the causes and extent of capacity and delay problems currently associated with the U.S. air system, projects the effects of increased air traffic on airport capacity over the next decade, and outlines various planned and ongoing FAA projects intended to reduce capacity enhancement areas: 1) airport construction and expansion; 2) revised airspace control procedures; 3) additional equipment and systems; and 4) capacity enhancement and planning studies. A description of each project is provided, along with significant milestones and estimates of the resulting capacity-related benefits. Keywords: Air traffic control systems.