The national airspace system is a complex, interconnected, and interdependent network of systems, procedures, facilities, aircraft, and people that must work together to ensure safe and efficient operations. DOT, FAA, airlines, and airports all affect the efficiency of national airspace system operations. DOT works with FAA to set policy and operating standards for all aircrafts and airports. As the agency responsible for managing the air traffic control system, FAA has the lead role in developing technological and other solutions to airspace issues. FAA also provides funding to airports. The funding that major airports receive from FAA to make improvements at the airports is conditioned on open and nondiscriminatory access to the airlines and other users, and the airlines are free to schedule operations at any time throughout the day, except at airports that are subject to limits on scheduled operations. The airlines can also affect the efficiency of the airspace system by the number and types of aircraft that they choose to operate. As we have previously reported, measuring the capacity of the airspace system and achieving its most efficient use are both difficult challenges because they depend on a number of interrelated factors. The capacity of the aviation system is not a simple measurable element—in addition to being related to airports’ infrastructure, capacity is affected at any given time by such factors as weather conditions and airline flight schedules. For example, because some airports have parallel runways that are too close together for simultaneous operations in bad weather, the number of aircraft that can take off and land is reduced when weather conditions worsen. Achieving the most efficient use of the national airspace system is contingent on a number of factors, among them the procedures that FAA uses to manage traffic, how well FAA’s air traffic control equipment performs, the proficiency of the controllers to efficiently use these procedures and equipment to manage traffic, and how much users are charged for the use of the airspace and airports. FAA has had a long history of attempting to address congestion by managing demand through administrative controls. FAA began establishing limits on the number of takeoffs and landings at five airports—Chicago O’Hare International, Newark, JFK, LaGuardia, and Washington Reagan National—in 1968. The High Density Rule, as it was known, instituted limits, or caps, on the number of takeoff and landings of the incumbent airlines serving each of the these airports. DOT lifted the restrictions at Newark in 1970, and in 2000, with the passage of the Wendell H. Ford Aviation Investment and Reform Act for the 21st Century (AIR-21), caps on operations were to be eliminated at Chicago O’Hare by July 2002, and at LaGuardia and JFK by January 2007. AIR-21 also immediately exempted certain types of aircraft from the caps, a change that resulted in unanticipated increases in demand, especially at LaGuardia. In 2000, airlines took advantage of AIR-21’s small regional jet exemptions and rapidly initiated a large number of new flights to and from LaGuardia. FAA chose to impose a moratorium on additional flights at LaGuardia in November 2000 to limit delays and reduced flights at LaGuardia to a level consistent with the airport’s capacity under optimal weather conditions. On the basis of this experience and FAA’s inability to adopt a final congestion management rule for LaGuardia, FAA issued a December 2006 order to maintain the cap of 75 hourly scheduled operations at LaGuardia until a final rule can be adopted. Chicago O’Hare also experienced increased operations after its caps were eliminated, prompting FAA to again limit operations at the airport beginning in spring 2004 through a series of voluntary agreements and ending with a new rule in late summer 2006. These caps on Chicago O’Hare’s operations are effective through October 2008, which coincides with the scheduled opening of the airport’s new runway in November 2008. In response to the near-record delays in summer 2007, which followed the expiration of the High Density Rule for the New York airports and increasing volumes of domestic air traffic, DOT convened a special aviation rulemaking committee (New York ARC) in the fall of 2007 specifically to address delays and other airline service issues in the New York metropolitan area. The New York ARC, which consisted of stakeholders representing government, airlines, airports, general aviation users, and aviation consumers, was tasked with identifying available options for changing current policy and assessing the potential impacts of those changes on airlines, airports, and the traveling public. The New York ARC had three specific objectives: (1) to reduce congestion, (2) to allocate efficiently the scarce capacity of New York area airports, and (3) to minimize the disruption associated with implementing any of the suggested improvements. The New York ARC issued its findings and options for reducing congestion to the Secretary of Transportation in December 2007. One of the committee’s working groups assessed 77 operational improvement initiatives for the New York area and identified key items to focus on within the list of 77, such as reducing excess spacing on final approach when landing. Nationwide, according to DOT data the annual number of domestic airline flight delays and cancellations has increased about 62 percent (from 1.2 million to 2.0 million), while the annual number of scheduled flights has increased about 38 percent (from 5.4 million to 7.5 million) since 1998. In the New York area, the trend is even more pronounced, as the number of domestic flight delays and cancellations at the three main commercial airports has increased about 111 percent, while the number of domestic operations has increased about 57 percent since 1998. DOT statistics indicate that 2007 was the second worst year on record for U.S. airlines’ on-time performance, and the trends in the percentage of flight delays and cancellations appear to be worsening. As shown in figure 1, about 20 percent of flights in the system were delayed and nearly 3 percent were canceled in 1998, compared to about 24 and 2 percent in 2007, respectively. The data also show that flight delays and cancellations have been steadily increasing since 2002, although the percentage of cancellations in 2007 is still lower than it was from 1998 through 2001. However, cancellations have become more problematic in recent years as the airline industry is now operating with fewer empty seats on flights. As a result, passengers on canceled flights must wait longer to be rebooked, and in some cases may be forced to spend the night before resuming travel the next day. Flights delays are also becoming longer. According to DOT data, the average length of a flight delay increased from more than 49 minutes in 1998 to almost 56 minutes in 2007, an increase of nearly 14 percent throughout the system. Despite this relatively small increase in average flight delay length, far more flights were affected by long delays in 2007 than in 1998. For example, the number of flights delayed by 180 minutes or more increased from 25,726 flights in 1998 to 64,040 flights in 2007, or about 150 percent. In addition, DOT’s data indicate that the number of flights in which an aircraft has departed the gate, but remained for an hour or more on the ground awaiting departure, has increased over 151 percent since 1998. Because the entire airspace system is highly interdependent, delays at one airport may lead to delays rippling across the system and throughout the day. This delay propagation appears to be increasing and leading to more delays in the system overall. For example, researchers at George Mason University’s Center for Air Transportation Systems have found that 46 percent of delays in the system in 2007 were caused by flight delays occurring earlier in the day. Flight delays in the New York metropolitan region also appear to have a disproportionate impact on delays experienced throughout the rest of the airspace system. During a typical day, approximately one-third of the aircrafts in the national airspace system move through the New York airspace. According to preliminary research conducted by the MITRE Corporation for FAA, an average of 40 percent of the flight delays in the system are from delays that originate in the New York metropolitan area. Compared to the rest of the country, where flight delays and cancellations have been steadily increasing, the magnitude and upward trend of the problem in the New York region is greater than the rest of the airspace system. For example, over a third of all flights in the New York metropolitan region in 2007 were delayed or canceled, according to DOT statistics. Figure 2 shows that the percentage of late arriving and canceled flights at each of the three major New York area airports was considerably higher than the systemwide averages. Since 2003, the percentage of late arriving and canceled flights has been increasing faster in the New York area than in the rest of the system. Since 1998, the New York area’s three major airports have often been among the airports with the lowest on-time performance records. In 2007, DOT reported that LaGuardia, Newark, and JFK had the lowest on-time performance rates among major domestic airports, followed by Chicago O’Hare International Airport, Philadelphia International Airport, and Boston Logan International Airport. Table 1 shows the ranking of major airports by the lowest on-time arrival performance in 2007. While DOT data show that the trends in delays and cancellations are getting worse, current on-time performance data do not capture the full extent of delays and cancellations or the extent to which passengers’ average travel times have increased in recent years. For example, airlines have, in many cases, opted to lengthen scheduled flight times to enhance on-time results, particularly along heavily congested and frequently delayed routes. DOT data do not account for the increased average flight times that are masked by these schedule changes. Also, available DOT data may not necessarily reflect passengers’ experience of delay because DOT tracks flights, not passengers. Passengers can experience delays to their trips because of missed connections resulting from delayed or oversold flights or lengthy delays due to flight cancellations—elements that are not measured in current statistics.