Aviation weather refers to any type of weather that can affect the operation of an aircraft—anything from a brief delay in departure because of low visibility to a catastrophic accident during flight. For example, in March 1992, a USAir flight crashed during takeoff from La Guardia Airport in New York City, killing 27 people and injuring 21 others. Icing was identified as one of the factors that contributed to that accident. According to data from the National Transportation Safety Board and FAA, about 24 percent of all aviation accidents in fiscal year 1987 through fiscal year 1996 were weather-related. During the same period, about 35 percent of aviation fatalities occurred in weather-related accidents. About 88 percent of these accidents involved small private aircraft. Weather-related aviation accidents were most often caused by winds, poor visibility, or turbulence. Figure 1 shows all the types of weather events cited in aviation accidents over this period. Multiple weather factors may be cited in an accident investigation. Because of rounding, the sum of percentages exceeds 100. Weather need not cause an accident to have an effect on aviation. FAA estimates that 72 percent of all delays over 15 minutes can be attributed to weather. These delays add to the cost of flying, either for passengers whose travel plans are disrupted or for airlines, which can incur additional fuel, servicing, and crew costs. The Air Transport Association estimates that delays cost airlines and passengers about $4 billion in 1996. (App. II provides more detailed information on weather-related accidents and delays.) FAA is responsible for maintaining the safety of the national airspace system. Because of the impact of weather on aviation, FAA has spent more than $1.4 billion in facilities and equipment funds since fiscal year 1982 to develop and purchase weather-related systems and equipment. In future years, FAA expects to spend another $440 million on those systems already in development. FAA believes that its purchases of improved weather systems will help it meet the President’s stated goal of reducing fatal aviation accidents by 80 percent within 10 years. For example, FAA has purchased more than 500 automated surface observing system (ASOS) units, which use a series of instruments to automatically measure such meteorological data as wind speed and direction, temperature, and barometric pressure near airports. FAA is also buying systems, like the integrated terminal weather system (ITWS), that will collect and analyze weather data from ASOS, radars, and other systems, and display them for use by air traffic controllers and supervisors. FAA relays the data provided by such systems, as well as information provided by the National Weather Service (NWS) and private vendors, to pilots through automated systems or direct voice communications from air traffic controllers. FAA also uses weather information when deciding how to handle air traffic, such as which runway to use at an airport. In addition, since fiscal year 1982, FAA has spent almost $169 million of its total funding of $3.3 billion for research, engineering, and development on research related to aviation weather. FAA’s research has looked into ways to improve radars and other weather sensors, to detect and avoid turbulence, and to support the early development of some of the systems it has purchased or plans to purchase. Much of this research is conducted under contract by several universities and federally funded laboratories, including the National Center for Atmospheric Research, the National Oceanic and Atmospheric Administration’s (NOAA) Flight Systems and National Severe Storms Laboratories, NWS’ Aviation Weather Center and National Center for Environment Prediction, and the Massachusetts Institute of Technology’s Lincoln Laboratories. Several other federal agencies also collect and disseminate aviation weather information, as well as conduct aviation weather research. NWS, which is part of NOAA in the Department of Commerce, is responsible for collecting, analyzing, and disseminating weather information in general and has worked with FAA on joint projects such as ASOS and an advanced national weather radar system. NWS also provides meteorologists for some of FAA’s air traffic control centers. Other agencies with related aviation weather responsibilities include the National Aeronautics and Space Administration, which conducts basic research on weather-related topics, and the Department of Defense, which provides aviation weather information to military pilots and command officers. The Office of the Federal Coordinator for Meteorology (OFCM), which is also part of NOAA, was created to coordinate the meteorological services and research for all federal agencies. However, the office does not have the authority to direct the weather operations of other federal agencies. Over the past 3 years, several reports have raised concerns about the quality of the weather information available to the aviation community. In 1995, NRC, examining the roles and missions of the agencies involved in aviation weather, found that FAA, NWS, and the other agencies involved did not coordinate their activities. NRC called upon FAA to take the lead in federal aviation weather efforts. At the same time, a subcommittee of FAA’s RE&D Advisory Committee that was examining the adequacy of FAA’s aviation weather research found a number of problems. This subcommittee reported that FAA needed to improve its aviation weather research as well as its delivery of weather information to system users, such as pilots, controllers, and dispatchers. Finally, FAA’s advisory committee released a report in 1997 on research related to the national airspace system. This report found that FAA’s efforts on aviation weather were unfocused and that the agency had not clearly defined its role in providing aviation weather information. We contacted the members of the NRC aviation weather committee and the FAA advisory committee that addressed weather issues and asked for their assistance in our efforts to follow up on their recommendations that were specifically addressed to FAA. In obtaining their assistance, we asked all of the committee members, in a survey, to identify the highest-priority recommendations. The highest-rated recommendations address three general topics: policy and leadership, interagency coordination, and efforts to address users’ needs. We chose an expert panel from among those who answered our survey, with members representing the various users of aviation weather information, such as airline representatives, commercial and private pilots, and air traffic controllers. The panel reviewed the information we had gathered on FAA’s actions to implement the eight recommendations and rated FAA’s general progress on each recommendation on a 5-point scale, from very poor to excellent. The panelists were also asked to indicate whether FAA’s actions were sufficient to address the recommendation and whether FAA had taken these actions in a timely manner. In discussing the recommendations, the panelists repeatedly raised concerns about FAA’s funding of weather activities, a fourth area of concern that was mentioned in the original reports. NRC and FAA’s RE&D Advisory Committee found that FAA did not exercise leadership for aviation weather services, partly because it lacked a clear policy on weather and partly because of organizational inefficiencies. FAA has attempted to address these criticisms by creating an aviation weather directorate and issuing a policy on weather. However, members of our expert panel did not think these actions went far enough to address the previously identified weaknesses, generally rating FAA’s progress in this area as poor. Reports by NRC and FAA’s RE&D Advisory Committee criticized FAA for failing to exercise leadership on aviation weather issues. For example, NRC found that “vigorous leadership within the federal government . . . needed to build consensus and coordinate the overall effort to optimize aviation weather services and related research.” It concluded that FAA was the agency best able to exercise that leadership because of its aviation expertise and legal authority. All three reports also criticized FAA for not developing a policy to define its role and priorities in aviation weather and recommended that FAA provide a clear policy statement on its role in providing aviation weather services. For example, NRC noted that under FAA’s policies, pilots have the primary responsibility for keeping their aircraft away from hazardous weather, while air traffic controllers are principally responsible for separating aircraft from one another, thus avoiding collisions. The report found that FAA’s guidance required controllers to remain aware of current weather conditions and relay information on hazardous weather to pilots, but it did not allow controllers to direct aircraft away from hazardous weather, as they direct aircraft away from other aircraft. NRC concluded that FAA should develop procedures that allow controllers to take a more active role in separating aircraft from hazardous weather, especially when they have more accurate weather information than the pilot. The 1995 advisory committee report reached similar conclusions. The 1997 advisory committee report concluded that even though the definition of hazardous weather is highly dependent upon the capabilities of the individual aircraft and flight crew, FAA’s mission should include the responsibility for transmitting weather information to pilots and dispatchers in order to improve the separation of aircraft from hazardous weather and to increase collaboration between pilots and air traffic controllers. NRC and FAA’s advisory committee also cited weaknesses in FAA’s internal organization as a reason for the agency’s not taking a leadership role in weather issues. For example, NRC found that no single office within FAA had the authority and responsibility for setting priorities for aviation weather. The 1997 advisory committee report found that six offices within FAA were responsible for setting priorities for aviation weather research. According to FAA’s Manager for Weather Research, prior to 1995, these offices did not set priorities to ensure that the most important research projects received funding. Instead, this official stated, FAA set its research priorities by reviewing the requests submitted by the national laboratories and contractors to the several offices with responsibility for aviation weather. These offices did not coordinate their efforts internally but submitted their requests separately to FAA’s Office of Research and Acquisitions. As a result, NRC and FAA’s advisory committee found that aviation weather research was hampered by a lack of coordination, funding, and priority setting. To address this problem, NRC recommended that FAA appoint an official to serve as the single focal point with responsibility for providing effective internal and external coordination of aviation weather activities. FAA took several actions to address concerns about its leadership role in aviation weather.