3
Current Services

The aviation weather system is not as effective as it could be. Aviation weather services that provide accurate and timely information about operationally significant weather are needed for effective decision making by pilots, controllers, and other users. The FAA and NWS should respond to urgent unmet user needs related to weather observation, analysis, forecasting, dissemination, and training.

One way to assess the near-term effectiveness of aviation weather services is to examine whether they meet user needs for accurate and timely information about operationally significant weather. This approach is consistent with the approach that the FAA itself is using to plan improvements in the aviation weather system. As noted in FAA Order 7032.15, "In the past, weather needs were based on the capabilities of proven technology. Today, because of the explosive pace of emerging technologies, a shift toward defining a weather system in terms of user operational needs is essential to allow the operational systems planning process to make the best use of technologies" (FAA, 1994b).

This chapter assesses the effectiveness of (1) currently available aviation weather services and (2) training programs for providers and users of aviation weather services. Based on these assessments, this chapter then identifies unmet user needs that should be addressed by improving existing systems and by developing new systems, as appropriate.

Aviation Weather Services

Within the United States, aviation weather services are provided to nonmilitary aircraft primarily by the FAA, the NWS, and the private sector. The Department of Defense (DoD) contributes to the national effort by sharing weather data produced under its auspices and by providing tailored weather services for military operations.

As shown in Figure 3–1, the process by which aviation weather services are provided can be divided into four phases:

  • observation;
  • analysis;
  • forecasting; and
  • dissemination.

All four phases must operate effectively for the overall aviation weather system to meet user needs; lapses anywhere along the chain jeopardize the outcome.

Observation

Comprehensive, up-to-date meteorological observations are necessary to meet the needs of the general public for accurate and timely reports of current and forecast weather conditions. Traditionally, the essential data needed to meet aviation weather needs were provided by hourly surface observations made by human weather observers stationed at airports, twice-daily upper-air observations made with the aid of inflatable weather balloons (i.e., rawinsondes), and unscheduled reports from pilots in flight. These basic observations are now augmented with a wide array of additional observational data from weather radars, visible and infrared satellite-imaging systems, automated aircraft reporting systems that collect upper-air wind and temperature data from en route aircraft, automatic wind profilers that use ground-based radars to measure upper-air winds, and automated surface weather observation systems. Data from these new systems have significantly enhanced the national meteorological database.

The NWS and U.S. Air Force collect or transmit most of the meteorological data used in the United States to operate national and global weather models. For example, each weekday the NWS receives more than 50,000 surface observations, over 4,000 upper-air observations, and approximately 8,000 automated aircraft reports. The



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--> 3 Current Services The aviation weather system is not as effective as it could be. Aviation weather services that provide accurate and timely information about operationally significant weather are needed for effective decision making by pilots, controllers, and other users. The FAA and NWS should respond to urgent unmet user needs related to weather observation, analysis, forecasting, dissemination, and training. One way to assess the near-term effectiveness of aviation weather services is to examine whether they meet user needs for accurate and timely information about operationally significant weather. This approach is consistent with the approach that the FAA itself is using to plan improvements in the aviation weather system. As noted in FAA Order 7032.15, "In the past, weather needs were based on the capabilities of proven technology. Today, because of the explosive pace of emerging technologies, a shift toward defining a weather system in terms of user operational needs is essential to allow the operational systems planning process to make the best use of technologies" (FAA, 1994b). This chapter assesses the effectiveness of (1) currently available aviation weather services and (2) training programs for providers and users of aviation weather services. Based on these assessments, this chapter then identifies unmet user needs that should be addressed by improving existing systems and by developing new systems, as appropriate. Aviation Weather Services Within the United States, aviation weather services are provided to nonmilitary aircraft primarily by the FAA, the NWS, and the private sector. The Department of Defense (DoD) contributes to the national effort by sharing weather data produced under its auspices and by providing tailored weather services for military operations. As shown in Figure 3–1, the process by which aviation weather services are provided can be divided into four phases: observation; analysis; forecasting; and dissemination. All four phases must operate effectively for the overall aviation weather system to meet user needs; lapses anywhere along the chain jeopardize the outcome. Observation Comprehensive, up-to-date meteorological observations are necessary to meet the needs of the general public for accurate and timely reports of current and forecast weather conditions. Traditionally, the essential data needed to meet aviation weather needs were provided by hourly surface observations made by human weather observers stationed at airports, twice-daily upper-air observations made with the aid of inflatable weather balloons (i.e., rawinsondes), and unscheduled reports from pilots in flight. These basic observations are now augmented with a wide array of additional observational data from weather radars, visible and infrared satellite-imaging systems, automated aircraft reporting systems that collect upper-air wind and temperature data from en route aircraft, automatic wind profilers that use ground-based radars to measure upper-air winds, and automated surface weather observation systems. Data from these new systems have significantly enhanced the national meteorological database. The NWS and U.S. Air Force collect or transmit most of the meteorological data used in the United States to operate national and global weather models. For example, each weekday the NWS receives more than 50,000 surface observations, over 4,000 upper-air observations, and approximately 8,000 automated aircraft reports. The

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--> Figure 3-1 National Aviation Weather System. (Source: FAA, 1994a) NWS receives additional inputs from weather radars, weather satellites, ships, ocean buoys, and other domestic and international sources. About 240 surface observation sites are staffed by NWS employees. Surface observations are made at over 1,000 additional sites by NWS contractors and automated systems, the FAA, DoD, other federal agencies, state governments, air carriers, and other private organizations. The FAA also supports the collection of meteorological data to meet the special needs of the aviation community. The FAA has developed—on its own or in cooperation with NOAA and/or the DoD—the following weather observing systems: Automated Weather Observing System (AWOS)—developed by the FAA; ASOS (Automated Surface Observing System)—developed by NOAA and the FAA; TDWR (Terminal Doppler Weather Radar)—developed by the FAA; Low Level Windshear Alert System—developed by the FAA; WSR-88D weather radars—developed by NOAA, the FAA, and DoD;1 airport surveillance radars with weather capability—developed by the FAA;2 and automated aircraft reporting of weather conditions—developed by the FAA and NOAA. The FAA also collects pilot reports about weather information. The FAA reports observational data that it collects from all of these sources to the NWS. The committee identified three areas of particular concern related to the ability of aviation weather services to meet user needs for aviation weather observations: number and location of weather observing sites; pilot reports and automated aircraft weather observations; and automation of surface observations. 1   The WSR-88D weather radar is also commonly referred to as NEXRAD, the NEXt Generation Weather RADar. 2   In areas that do not yet have weather radar coverage, the NWS extracts weather information from air waffle control radars operated by the FAA.

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--> In addition, as discussed in Chapter 4 (pages 44 and 45), the committee also is concerned about the need for new sources of meteorological data, especially atmospheric humidity, icing, and turbulence. Number and Location of Weather Observing Sites Aviation in many parts of the United States is adversely impacted by the limited availability of weather observations. Although weather radar and satellite observations can provide useful information in data-sparse regions, such observations do not include parameters such as visibility, surface winds, and atmospheric pressure that are important to aviation users. Thus, surface weather observations remain an important source of meteorological data for aviation. In some cases airports have instrument approaches, but pilots cannot operate under instrument flight rules without official weather observations. This situation will become more common as changes in the air traffic system allow more pilots to use navigation signals from the Global Positioning System to conduct instrument approaches at small airports that currently lack this capability. The availability of weather observations is also an issue in remote regions of Alaska and in mountainous portions of the west (see Chapter 5, page 48). Mountainous terrain increases the need for weather observing sites for several reasons: Mountain ridges limit the horizon of weather observers; the far side of the ridge becomes an area of meteorological uncertainty. Mountains often create small-scale weather phenomena that may not be detected by existing weather observing systems or forecast by available weather forecasting techniques. Mountainous terrain may restrict the movement of small aircraft, limiting their ability to avoid or escape from unexpected adverse weather that they may encounter. Currently, there are few affordable options for significantly increasing the number of weather observing sites in remote or mountainous regions. Automated weather observing systems require electrical power, communications, and periodic maintenance that can be quite difficult to provide in remote or mountainous regions where observations are most needed. Likewise, establishing and maintaining a weather observing site staffed by NWS-certified weather observers is often not an affordable option, in part because current standards require certified weather observers to accurately classify a wide range of weather phenomena. One way to foster the proliferation of official nonfederal (i.e., state, industry, or site-specific volunteer) weather observing sites would be to establish one or more classifications of weather observers, who would be trained and certified to provide partial weather observations. These observers would be able to provide essential information, such as cloud ceiling, visibility, temperature, barometric pressure, runway condition (at airport locations), and precipitation. In many areas, local pilots currently plan their flights by calling personal contacts along their flight path and at their destination to obtain this type of information unofficially. Training and certifying sources of partial weather observations would increase the accuracy of these observations and improve the dissemination of information by making it possible to process these observations as ''official" weather observations. The Alaska Airmen's Association recently initiated a similar effort by encouraging pilots to make pilot reports of adverse weather conditions in remote regions even if they are on the ground and not engaged in flight-related activities. (The Airmen's Association suggests making these "pilot reports" via telephone to the AFSS [Automated Flight Service Station] in Alaska that receives such reports from pilots in flight.) The FAA already encounter pilots to report weather conditions that they encounter in flight, and these observations are processed and disseminated by the FAA and NWS even though pilots generally are not trained or certified as official weather observers and may have very limited meteorological training. Recommendation: The NWS should foster the proliferation of official non-federal weather observing sites by establishing one or more additional classifications of surface weather observers, who would be trained and certified to provide partial weather observations. Pilot Reports and Automated Aircraft Weather Observations Pilot reports are an excellent source of localized, altitude-specific observations of weather conditions such as icing, turbulence, and cloud type that are important to aviation and that may be hard to obtain otherwise. Nonetheless, as-emphasized by Weather for Those Who Fly (NRC, 1994), pilot reports have long been an underused resource. Such reports are aperiodic, labor intensive, cumbersome, and often unformatted. Pilots must make a verbal report to an air traffic controller who may be too busy controlling traffic to deal with weather reports, or they must change radio frequencies to contact a FSS (Flight Service Station) or AFSS. Once pilot reports have been received by an air traffic controller or flight service specialist, he or she must write down the information and

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--> then pass it along so it can be processed. As a result, many pilot reports never make it into the aviation weather data collection system. Pilots, controllers, and flight service specialists need encouragement to generate and disseminate pilot reports. In addition, processing and dissemination systems should make it easier for users to sort through and obtain useful information from pilot reports quickly. Several air carriers use the Meteorological Data Collection and Reporting System (MDCRS) to provide the NWS with automated aircraft observations. MDCRS receives information on upper-air winds and temperature from specially equipped commercial aircraft and translates it into a standard format for use by the NWS. The FAA funds the operation of MDCRS, but air carriers must pay for the cost of automated meteorological sensors for their aircraft and for air-to-ground transmission of data.3 Airlines receive no financial compensation from either the FAA or the NWS for providing MDCRS observations. The fact that air carriers continue to provide MDCRS data indicates that the benefits they receive exceed the additional costs involved. Nonetheless, individual air carriers are paying to generate meteorological data that are of general benefit to the aviation community and national forecasting capabilities. Automated aircraft reporting significantly increases the availability of in flight meteorological data. United Airlines recently shifted to the use of automated reporting in lieu of pilot reports for routine reports of position, wind, and temperature. As a result, it started receiving approximately 8,000 reports per day instead of 200–300 reports per day. The U.S. Weather Research Program Implementation Plan recommends substantially increasing the number of aircraft equipped to collect MDCRS data and expanding the MDCRS effort to include humidity data. 4 Currently, the FAA is sponsoring the development of humidity and turbulence sensors for use with MDCRS. However, despite the current value and future promise of automated aircraft reporting, neither the FAA nor the NWS has definitive plans to expand MDCRS or to establish it permanently as an operational weather observing system. Recommendation: The FAA should ensure that long-term operational funding is provided for MDCRS. In addition, the FAA should enhance the value of MDCRS by encouraging more air carriers to participate in the program. Automation of Surface Observations Surface observations generally include detailed information about atmospheric conditions at a particular site, including temperature, barometric pressure, dew-point temperature, altimeter setting, visibility, clouds, precipitation, and wind speed and direction. Both the NWS and the FAA are increasingly relying on new technologies to replace labor-intensive manual weather observations with automated observing systems. Many automated surface observing systems are being located at or near airports. The proper operation of these units is important to meet the needs of aviation. The FAA initiated acquisition of automated surface observing systems in 1988 when it issued a contract to acquire 160 AWOS units for deployment at airports that had no certified weather observers. Although AWOS was not intended to duplicate all of the functions that a human weather observer provides, it does provide certified weather data such as ceiling, visibility, wind speed and direction, and altimeter settings. State governments have also procured about 275 AWOS units. Most of these units are connected to the national data collection system, but states have sometimes had a difficult time connecting to the system. In some cases, changes in technical specifications associated with the federal system created incompatibilities with state systems, and states have sometimes balked at paying to modify their systems to accommodate these changes. The availability of weather observations from state AWOS units that are not connected to the federal system is limited to individual state-operated weather dissemination systems. In 1991 the NWS, with FAA support, issued a contract to acquire ASOS. ASOS is an improved weather observing system that is the centerpiece of the NWS plan to replace human weather observers with automated systems as part of the NWS Modernization Program. The NWS, FAA, and DoD intend to install a total of 868 ASOS units by fiscal year 1997 at a cost of $351 million (GAO, 1995b). Table 3-1 depicts the status of this process as of December 2, 1994. Like AWOS, ASOS can be a valuable source of weather observations. ASOS units provide a continuous weather watch and enable instrument flight operations at airports where human weather observers are not assigned or are on duty less than 24 hours per day. For example, ASOS provides arriving pilots with up-to-date altimeter settings that are valuable to all pilots and are essential for instrument landings (at night and during inclement weather). In addition, tower controllers at airports with- 3   Data are transmitted from aircraft to the ground via the Aeronautical Radio, Inc. (ARINC), Communications Addressing and Reporting System (better known as ACARS), which is owned and operated by ARINC on behalf of U.S. commercial air carriers. MDCRS Collects data that ACARS has already collected on the ground. 4   The U.S. Weather Research Program is an interagency effort that includes the Department of Transportation, Department of Commerce, DoD, NASA, and the National Science Foundation.

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--> TABLE 3-1 Status of Commissioning ASOS Units (Source: GAO, 1995b)   Units Purchased Units Delivered Units Commissioned NWS 232 159 45 FAA 352 312 2 DoD/Navy 33 20 Not Applicablea a NWS commissioning procedures do not apply to Navy ASOS units. out NWS weather observers will benefit from ASOS because it will relieve them of their current responsibility for making weather observations and will allow them to focus on controlling aircraft. Automated systems also offer the potential of consistent and reliable weather observations that are not affected by human variability in making weather observations. Implementation of the ASOS system has involved some problems. In particular, many aviation users believe that replacing full-time human weather observers with ASOS units, as they are currently designed, produces a degradation in service to the aviation community. Appendix E (page 82) discusses the following specific issues associated with ASOS system performance: availability of the data communications system; interpretation of ASOS readings; instrument performance and system development testing; completeness of the weather observation; equal or better level of service; augmentation of ASOS observations; access to ASOS data; authority of controllers to override ASOS readings; maintenance and backup; and site selection. Concerns about ASOS are not new. In 1991 the National Research Council determined that "although ASOS offers some clear advantages over the present surface observation method in operational weather forecasting and warning, serious concerns exist about its accuracy, representativeness, and system performance" (NRC, 1991). ASOS system performance is also the subject of a recent report by the General Accounting Office (GAO) (GAO, 1995b). The GAO concluded that "ASOS is performing neither as intended or expected.... While ASOS meets many of its specified requirements ... six of eight sensors in the ASOS system do not meet key contract specifications for accuracy or performance." The GAO also determined that ASOS "does not provide certain capabilities that some users say are critical to ensuring safe aviation.... While the NWS has corrective actions under way, it has determined neither the full range of problems that it will address nor how much the system enhancements or supplements needed to do so will cost.... ASOS problems in meeting both specified requirements and user needs [that go beyond the scope of existing ASOS system specifications] ... have yet to be resolved." Although the NWS did not concur with many of these conclusions (DOC, 1995), the GAO report does illustrate the type of criticism that ASOS continues to attract from some aviation users. The committee did not conduct a detailed assessment of issues associated with the automation of aviation weather services such as those described above for ASOS. However, in the opinion of the committee, lessons learned from the ASOS acquisition experience include the following: Users should be fully involved in the acquisition of new systems that will impact the aviation weather services upon which they depend. The NWS relies on the FAA to define aviation user requirements for meteorological systems. As a result, the FAA should ensure that it accurately assesses the needs of all segments of the aviation community and translates those needs into system requirements. The best time to build user acceptance is while systems are being developed. This becomes much harder and more costly after systems have been fielded, especially if user confidence is shaken by a negative first impression. System acquisition managers should fully develop strategies and implementation plans with other relevant offices and agencies to ensure that the deployment of new systems accommodates related system interfaces, agency staffing, logistical support, regulatory requirements, and training for agency staff and other system users. Extended field testing in an operational environment should be performed to ensure that systems with cutting edge technology are ready to enter service. Whenever practical, installation should include an overlap period during which data are collected from both existing and new sensors. This would give users an opportunity to become more aware of characteristic differences in the two data sets. (It would also make the data somewhat more useful in tracking climatic change.) Senior officials within both the FAA and the NWS seem to recognize that their involvement will be necessary to ensure that systems developed in the future benefit from the ASOS experience. In addition, despite the difficulties

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--> encountered with ASOS, the committee remains confident that automation of aviation weather services offers the potential to reduce costs and increase quality. Recommendation: The FAA and NWS should continue to resolve user-identified issues associated with ASOS and use the lessons learned from the ASOS acquisition to improve the process by which new systems are conceived, developed, and deployed. Analysis Analysis is the critical link between weather observations and forecasts. Analysis produces an integrated description of the atmosphere that is consistent with observed data. This description takes the form of data sets and graphics that describe and depict the geographic distribution of weather parameters such as temperature, pressure, radar reflectivity, cloud cover, and wind. These data sets also define the initial conditions needed to generate numerical weather forecasts. Within the aviation weather community, data analysis focuses on the aviation impact variables—such as ceiling, visibility, turbulence, and icing—that are particularly important to flight operations. In some cases private weather services that market customized services use observational data sets and analysis products produced by the NWS as the foundation for generating their own analysis products. However, the vast majority of analysis products are produced directly by the NWS. The committee identified one area of particular concern related to the ability of aviation weather services to meet user needs for analysis of meteorological data: new automated observing systems are greatly increasing the quantity of meteorological data that must be analyzed. To accommodate this increase, the NWS is improving its information processing capabilities. In addition, the FAA is funding the NOAA Forecast Systems Laboratory to develop the Aviation Gridded Forecast System. This system will analyze observational data to create a three-dimensional gridded data set of observed, calculated, and short-term forecast weather data that impact aviation. The gridded data set will serve as a common source of data for aviation forecasters at the NWS and elsewhere. As a result, the Aviation Gridded Forecast System offers the potential to increase the level of consistency and compatibility among a wide variety of aviation weather products. Recommendation: The FAA and NOAA should maximize the payoff of national investments in new weather observing systems by implementing improved information processing systems and new data analysis tools such as the Aviation Gridded Forecast System. Forecasting Forecasting uses observed and analyzed weather data to produce weather forecasts that project the current state of the atmosphere into the future. The NWS's National Centers for Environmental Prediction (formerly the National Meteorological Center) in Suitland, Maryland, operates a variety of national and global numerical models to produce national, global, and oceanic analyses and forecasts. These analyses and forecasts, together with information from other sources, serve as a basis for more specialized forecast products, including both generalized weather forecasts and products aimed at specific users, such as terminal, en route, and oceanic forecasts for aviation. Terminal forecasts cover geographic regions in the vicinity of an airport and provide information that pilots need for take off and landing. En route forecasts cover flight paths between the point of departure and destination. Oceanic forecasts (for aviation) describe weather conditions for long distance flights over ocean areas. Aviation weather forecasting has much in common with other types of forecasting, such as severe storm forecasting. In fact, the NWS's National Aviation Weather Advisory Unit is an element of the National Severe Storms Forecast Center. Nonetheless, aviation weather forecasting has different concerns than general forecasting. For example, extended rainfall may have only a moderate impact on aviation, while associated flooding could seriously impact the general public. A long line of thunderstorms, on the other hand, may interrupt flight operations in a wide region, even though it may not have significant impact on the general public. Accurate forecasts are necessary for efficient planning of flight operations. Terminal forecasts are particularly important because most weather-related accidents and delays are associated with adverse weather in terminal areas. NWS aviation forecasters in local weather offices produce terminal forecasts for designated airports in their areas of responsibility. This responsibility is being assigned to the 118 Weather Forecast Offices that the NWS is establishing as part of the NWS Modernization Program. In addition, the FAA funds the NWS to provide dedicated support to aviation by operating the following aviation weather facilities: The National Aviation Weather Advisory Unit in Kansas City, Missouri. This unit generates short-term (6-to 12-hour) regional aviation forecasts and hazardous aviation weather advisories for the 48 contiguous states. (The NWS regional offices in Honolulu and Anchorage provide these services for Hawaii and Alaska, respectively.)

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--> The Central Flow Weather Service Unit at the FAA's Air Traffic Control System Command Center in Reston, Virginia. NWS meteorologists at this unit produce tailored forecasts to support day-to-day strategic planning of aviation within the United States and along oceanic routes leading to and from the United States. A Center Weather Service Unit (CWSU) at each of the FAA's 21 Air Route Traffic Control Centers (ARTCCs). The ARTCCs are responsible for en route flight operations within the United States. Each CWSU prepares tailored forecasts for the air traffic control supervisors and air traffic managers at the corresponding ARTCC.5 Each of these facilities uses a mixture of individual weather products that they obtain from either the NWS or private weather services. The private weather services, in turn, access data and information (for a fee) from the NWS and other sources for repackaging and resale to public and private users. New resources such as the Aviation Gridded Forecast System database should increase the access of private vendors to NWS analysis and forecast products and significantly improve the quality of aviation weather products that are developed by both the NWS and the private sector.6 The committee identified four areas of particular concern related to the ability of aviation weather services to meet user needs for aviation weather forecasts: use of forecasts prepared by private weather services; short-term forecasts/nowcasts; geographic resolution of weather forecasts; and feedback from users to aviation weather forecasters. Use of Forecasts Prepared by Private Weather Services The FAA separately approves the process that each air carrier uses to obtain required meteorological information. As a result, even though the FAA may approve the use of a particular set of weather products by one air carrier, other air carriers cannot use them as an essential element of their meteorological process unless the FAA grants them specific permission to do so. This policy complicates the process that air carriers must use to adopt new and improved weather products that private weather services make available. FARs (Federal Aviation Regulations) require that pilots of all types use weather information from "approved sources." In many cases pilots and dispatchers obtain some of their weather information from private weather services, television weather programs, and newspapers. However, neither the FAA nor the NWS certify weather products provided by such sources. In fact, there is no mechanism for private weather services to be designated as an "approved source" of weather information for general or business aviation pilots, even though many of these pilots routinely rely on private weather services for preflight weather information. One of the reasons that the NWS declines to certify any private weather services as an approved source of meteorological information for aviation is its concern that it might be held liable if an NWS-approved private weather service produced an inaccurate weather product that contributed to an aircraft accident. However, the committee notes that the FAA licenses pilots and regulates the manufacture and maintenance of aircraft, yet the FAA assumes no liability if licensed or certified pilots, aircraft manufacturers, parts suppliers, or mechanics make an error in judgment or provide a defective product that results in an aircraft accident. Thus, it should also be feasible to license qualified private weather services. Recommendation: The FAA and NWS should develop a procedure to designate private weather services as approved sources of specific aviation weather products. Short-Term Forecasts/Nowcasts Most domestic flights last less than 5 hours. Therefore, short-term forecasts that cover the next 6 hours or so are of particular interest to aviation. In addition, airport "nowcasts," which cover the next 30–60 minutes, are especially important to allow air traffic controllers and pilots to coordinate the position of arriving aircraft to accommodate short-term weather phenomena such as thunderstorms and windshear. The NWS recently conducted a study of terminal forecasts that concluded that the accuracy of forecast ceiling and visibility at 90 airports in the United States did not seem to have improved between 1983 and 1994. That study also concluded that the 3-hour forecasts of ceiling and visibility that are contained in terminal forecasts are generally less accurate than 3-hour "persistence forecasts." In other words, based on that study, assuming that observed ceiling and visibility will remain unchanged for the next 3 hours is more accurate, on average, than NWS terminal forecasts of ceiling and visibility (Dallavalle and Dagostaro, 1995). 5   Air traffic controllers maintain tactical control of designated aircraft to prevent aircraft collisions. Air traffic managers at the national Air Traffic Control System Command Center and the 21 regional ARTCCs regulate overall traffic flow to avoid overloading individual airports by allowing too many incoming aircraft to arrive at one time, especially in cases of adverse or deteriorating weather conditions. 6   Chapter 6 (pages 57 and 58) addresses the balance between services provided by the NWS and private weather services.

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--> Recommendation: The NWS should continue ongoing efforts to increase the availability and accuracy of short-term forecasts and nowcasts. Geographic Resolution of Weather Forecasts During cold weather, current forecasting methods may conclude that potential icing conditions exist over hundreds of thousands of square miles of U.S. airspace. Icing, however, is usually a localized phenomena. A recent comparison of icing forecasts with pilot reports of icing determined that 70–80 percent of icing forecasts may be false alarms. In addition, even though current methods predict that icing hazards exist over very large geographic areas, this comparison determined that, for the data set examined, about 20–30 percent of icing events reported by pilots were not predicted by current forecast methods (Brown et al, 1995).7 As a result, current forecasting methods are usually not a useful tool for determining whether an individual pilot on a specific flight will actually encounter icing. Current methods also have limited abilities to produce localized predictions of other weather phenomena, such as turbulence, thunderstorms, and windshear, that are of particular interest to aviation. Improved forecasting methods would increase the ability of pilots and dispatchers to avoid these hazards by modifying their flight plans. Recommendation: The NWS should continue ongoing efforts to increase the accuracy, timeliness, and geographic resolution of en route and terminal forecasts, especially with regard to icing and turbulence. Feedback from Users to Aviation Weather Forecasters NWS Weather Forecast Offices may issue two or three forecasts daily for a dozen or more airports. However, in contrast to the meteorological organizations of military services and commercial air careers, Weather Forecast Offices receive little or no feedback from pilots or other users regarding the accuracy, impact, or overall utility of their forecasts. Accurate feedback is important to assess and improve forecasting skills and methods. Recommendation: The FAA and NWS should develop a process to allow pilots and other users of airport terminal forecasts to provide timely feedback to the NWS forecasters who generate these forecasts. Dissemination Dissemination involves the delivery of aviation weather information to a wide variety of users. This information may consist of raw observational data, analyzed data, or forecast information. In most cases, the information is packaged in the form of a standardized audio, alphanumeric, or graphic weather product that is familiar to intended users. (Alphanumeric weather products, however, typically use coded abbreviations that are difficult for many users to interpret efficiently.) Depending upon the situation, weather information may be transmitted from person to person using telephone, radio, or face-to-face conversation; by a recorded or computer-generated telephone or voice message; by computer modem; or by other modern forms of telecommunications. Preflight weather information enables pilots to plan for expected weather along their routes of flight. En route weather information enables them to monitor changing weather conditions and adjust their flight plans as necessary. To illustrate this process, Appendix F (page 86) contains descriptive scenarios of two sample general aviation flights.8 Both scenarios are taken from FAA Order 7032.15 (FAA, 1994b). The first example is based on the air traffic control system as it existed in 1994 and identifies the following operational shortcomings: General aviation pilots who rely on the FAA for their preflight and en route weather may receive information that is "incomplete, inconsistent, and outdated." Radar information is "often too old to be useful by itself." Flight service specialists (1) spend too much time interpreting alphanumeric data, (2) may be "unable to relay accurate information on thunderstorm cells and the exact location of potential icing and turbulence," and (3) may be unable to disseminate pilot reports of adverse weather conditions "at their time of receipt because of equipment limitations" and workload constraints. The exchange of weather information between pilots and air traffic controllers "was time-consuming, work-intensive, and caused [radio] frequency congestion that affected airspace capacity and ATC [air traffic control] efficiency." The committee concurs with this assessment. 7   This study compared archived data from pilot reports with icing conditions predicted by several different forecast models. Results varied widely from model to model and as a function of altitude. On average, however, only 20–30 percent of icing forecasts were verified by pilot reports. Lack of consistency between forecast conditions and reported conditions is caused by model inaccuracies and by the fact that pilot reports do not constitute a comprehensive and error-free record of meteorological conditions. Some occurrences of adverse weather are not reported by pilots, and some pilot reports are not fried and retained in official records. 8   Similar scenarios are also included in Weather for Those Who Fly (NRC, 1994).

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--> The second scenario described in Appendix F describes what it might be like for a general aviation pilot in the year 2015. As reported in Appendix F and other FAA documentation, the FAA anticipates that changes in the federal aviation weather system will increase the efficiency of providing aviation weather services, improve flight safety, and increase airspace capacity. To accomplish these goals, the FAA plans to improve its communications and display systems and rely more on automated systems to observe the weather and generate forecasts, warnings, and other weather products that are tailored to meet the specific needs of pilots, controllers, and other aviation users (FAA, 1994a; FAA, 1994b). The committee agrees that the improvements illustrated in the 2015 scenario are worthwhile, and it believes that the federal government should be able to implement most of them in significantly less than 20 years. The committee identified six areas of particular concern related to the ability of aviation weather services to meet user needs for dissemination of aviation weather information: federal efforts to reduce dissemination costs; form and content of weather products; dissemination to pilots en route; role of air traffic controllers; effectiveness of Center Weather Service Units; and dissemination to airport operators. Federal Efforts to Reduce Dissemination Costs The FAA disseminates preflight weather information to individual pilots using FSSs (Flight Service Stations), AFSSs (Automated Flight Service Stations), and the Direct User Access Terminal Service (DUATS). Like much of the federal government, the FAA is under increasing pressure to cut costs (See Appendix G, page 90). The FAA views dissemination of preflight and en route weather information as one area where it may be able to reduce expenses. However, the effort to reduce costs should be carefully managed to ensure that users have continued access to quality aviation weather services. The FAA has nearly completed the process of consolidating and modernizing its flight service network, which consisted of 317 FSSs in 1981, into a more compact network of 61 AFSSs and 31 part-time or seasonal FSSs, which will provide supplemental service in ''locations of unique weather or operational conditions" such as Alaska (FAA, 1995a). This consolidation is reducing the cost of providing flight services, but neither the user community nor the FAA seems to be satisfied with the outcome of the ongoing consolidation. Most users of AFSSs and FSSs are pilots of general aviation, business aviation, and small commuter aircraft. Prior to shutting down the old FSSs, the FAA made a commitment to these users that the process of consolidating and automating FSSs would result in an equal or better level of service. In fact, based on their experience with the consolidated network, many users view the new system as an improvement. However, many other users believe that the FAA needs to improve the quality of services that AFSSs provide in order to meet its commitment to equal or better service. These users often point to the impact of losing local weather briefers who are knowledgeable about local weather conditions. In addition, even though the FAA has invested hundreds of millions of dollars in this modernization and consolidation effort, some users question the utility of the new weather briefing systems that have been installed. They also have ongoing concerns about the effectiveness of the next generation of AFSS weather briefing systems (i.e., the Operational and Supportability Implementation System, which is better known by its acronym, OASIS) that the FAA intends to procure during the next few years.9 Within the FAA, which originally proposed consolidating all 317 FSSs into just 3 facilities, aviation weather managers interviewed by the committee continue to question the need for government-provided flight services, and a recent FAA-sponsored assessment of flight services concluded that functions such as preflight weather briefings and flight planning that are now provided by FSSs and AFSSs could "readily be assumed by soon-to-be-available technology" (Banks, 1995). However, a more-comprehensive FAA-sponsored study concluded that FSSs and AFSSs should continue as the primary means of disseminating preflight information for the foreseeable future (FAA, 1994d). DUATS, which became operational in February 1990, provides pilots with an alternate source of preflight weather information (besides FSSs and AFSSs). The FAA only authorizes active pilots (i.e., those with a current license and medical certificate) to access DUATS. The purpose of this policy is to limit DUATS use to those pilots who really need it (i.e., those who are fully certified to fly). DUATS is provided by two commercial vendors under contract to the FAA. The vendors are reimbursed on a per-use basis by the FAA, so the vendors compete with each other to attract users. DUATS is used by civil- 9   The committee is not aware of any scientific surveys of aviation weather users. User opinions described here and elsewhere in the report are based on the personal experience of committee members, views expressed at public meetings related to aviation weather, and informal surveys conducted by the Aircraft Owners and Pilots Association and the Alaska Aviation Safety Foundation.

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--> ian pilots of all types, although most users are general aviation pilots. DUATS allows pilots to carry a record of current meteorological data with them in flight. However, it provides no opportunity for human interaction. Also, as illustrated in Weather for Those Who Fly (NRC, 1994), standard DUATS weather briefings contain no graphic weather information. Instead, pilots normally receive pages of coded data that they must interpret to build their own picture of the weather. This can be a difficult task, and many pilots prefer to call a weather briefer at an FSS or AFSS instead of, or in addition to, obtaining weather information from DUATS.10 The FAA charges no user fees for either DUATS or FSS/AFSS services. In order to reduce its costs, the FAA eliminated funding for DUATS in its proposed budget for fiscal year 1994, but funding was restored by Congress. During fiscal year 1993, DUATS services cost the FAA about $10 million, or $1.67 per call. By comparison, the preflight services provided by FSSs and AFSSs cost the FAA about $220 million during fiscal year 1993, or $5.00–$9.00 per call (Thomas, 1995; GAO, 1994; FAA, 1994d).11 This cost differential indicates that DUATS can produce cost savings if it reduces the need for pilots to contact FSSs and AFSSs. DUATS-like services also could reduce dissemination costs by improving the ability of FSSs and AFSSs to disseminate weather information efficiently. For example, weather briefings would probably take less time if both pilots and flight service specialists could view some of the same weather products. This could be accomplished if a new DUATS-like service and improvements to the weather information systems installed in AFSSs allowed flight service specialists to access pilots' DUATS weather briefings and discuss any questions pilots may have. This also could be accomplished if the FAA disseminated some of the graphic weather products and decision aids used by flight service specialists to pilots via telefax or as part of an improved DUATS-like service. (See Scenario Two in Appendix F, page 88.) Recommendation: The FAA should implement an improved DUATS that (1) makes it easier for pilots to understand what weather conditions are likely to impact their specific flights, (2) improves user access to graphic weather products (perhaps by using communications systems such as the Internet), and (3) improves the efficiency of pilot weather briefings by flight service specialists. Because of their meteorological training and experience, flight service specialists are better equipped than many general aviation pilots to make meteorological judgments. In fact, many general aviation pilots believe that it is extremely important to have the option of calling an FSS or AFSS and talking to a human weather briefer, especially when weather conditions are marginal or uncertain. As a result, flight service specialists sometimes serve as a critical element of flight safety as they help pilots interpret weather information prior to and during flight. Recommendation: Flight service specialists should remain available as a source of preflight and en route weather information for general aviation and business pilots. Form and Content of Weather Products One of the FAA's key goals for the federal aviation weather system is to enable all users to plan for—rather than simply react to—operationally significant weather. The FAA anticipates that accomplishing this goal will involve providing users with weather products that feature improved accuracy, timeliness, and resolution; are tailored to meet specific user needs; present information in ways that users can easily assimilate; and provide different types of users (e.g., pilot and controllers) with consistent information, thereby contributing to shared situational awareness (FAA, 1994b). Shared situational awareness occurs when different users have a common understanding of current and forecast weather conditions. Currently, pilots, controllers, and dispatchers often obtain weather information from different sources that may not agree about the location, duration, or severity of adverse weather. In some cases weather products generated by the current aviation weather system do a poor job of meeting the needs of pilots. For example, DUATS inundates pilots with a great deal of meteorological data that apply to a broad geographic region in the vicinity of the proposed flight. As a result, it is difficult for users to identify the information that applies to their specific flight. Tailored route-and user-specific weather products are more useful than all-encompassing weather products that make it difficult for individual users to identify the information that applies to their particular situation. The FAA, NWS, and private weather services are already working to improve the form and content of aviation weather products by developing new products that make greater use of graphics. As illustrated in Weather for Those Who Fly (NRC, 1994), graphic weather products can provide users with multiple options for viewing 10   As a third alternative, pilots can also contact private weather briefing services, which usually operate on a fee-per-use basis. See Chapter 6 (pages 57 and 58) for more information on the role of the private sector in providing aviation weather services. 11   The total cost of operating FSSs and AFSSs during 1993 was about $350 million. However, these facilities provide a variety of preflight and en route services, and it is difficult to accurately estimate the actual cost of a specific preflight service.

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--> and assessing the current and forecast state of the atmosphere along proposed flight paths. Many graphic weather products are already being tested in applied research laboratories. These new products will be easier for pilots and other users to understand than the long, coded text reports that are common in the current aviation weather system. Future dissemination systems will need to accommodate these products and other changes in the aviation weather industry. Recommendation: The FAA should take the lead in developing tailored and consistent graphic aviation weather products that feature improved accuracy, timeliness, and resolution.12 Dissemination to Blots En Route Pilots need access to better weather information, not more data. For example, pilots preparing to land or take off need concise information to help them make a go/no-go decision. Although important information is often available on the ground, there are few options for transmitting it to pilots in the air. Many airline dispatch offices, air traffic control facilities, and weather forecast offices have access to a wide variety of full-color graphic weather products that display up-to-date local, national, and even global weather information. However, except for voice radio, general aviation aircraft, commuter airlines, and even some air carriers typically have no ability to receive or display weather information en route. In order to improve the dissemination of weather information to pilots, the FAA is attempting to develop a widely acceptable system for en route dissemination of weather information in graphic form. In order to achieve wide acceptance, such a system will need to meet user needs in areas such as: Cost of equipment and services. Upgrading or replacing avionics is an expense that owners of commercial, business, and general aviation aircraft are reluctant to make unless there is a compelling economic or safety-related justification. Pilot workload. Improved weather information systems will be a mixed blessing if they increase pilot workload. During critical phases of flight, pilots cannot afford to divert very much of their attention from flying the aircraft, especially during adverse weather when up-to-date weather information is most critical. This is particularly true for general aviation pilots, who rarely have a copilot to provide assistance. Design features and human factors. New cockpit weather systems should be appropriate to the typical level of pilot training and expertise for each type of aircraft. For example, complex systems can easily overwhelm general aviation pilots who have limited flight experience. Access restrictions. Pilots and aircraft owners do not want to be excluded from major airports by requirements for expensive new equipment that they cannot afford. New dissemination systems should also consider the special needs of small but important user groups such as rotorcraft operators. For example, rotorcraft often engage in search and rescue or medical evacuation missions that use nonstandard flight paths and emergency landing zones that may be miles from the nearest airfield or official weather observing site. Finding: The limited capabilities of existing cockpit display and ground-to-air communications systems are the largest technical impediments to improving dissemination of graphic weather information to pilots en route.13 Recommendation: The FAA-should support ongoing work that addresses shortcomings in cockpit display and ground-to-air communications systems. The FAA should also continue to provide voice radio links to weather briefers on the ground, such as those currently provided by AFSSs, until a practical alternative system is fielded. Role of Air Traffic Controllers There are three types of air traffic controllers:14 En route controllers at ARTCCs (Air Route Traffic Control Centers), who control the movement of en route aircraft operating in accordance with an instrument flight plan.15 This includes virtually all flights by commercial air carriers. TRACON (Terminal Radar Approach Control) controllers, who control the movement of low-altitude aircraft that are between 10 and 50 miles from major airports. More-distant aircraft are the responsibility 12   See Major Recommendation 3 (Chapter 3, page 39) and Major Recommendation 6 (Chapter 6, page 55). 13   See Major Recommendation 3 (Chapter 3, page 39) and Major Recommendation 6 (Chapter 6, page 55). 14   FAA documentation often refers to air traffic control specialists, a term that includes the three types of controllers described above plus flight service specialism, who work at FSSs and AFSSs. 15   The FAA also offers a flight-following service for pilots operating under visual flight rules. Pilots use the En Route Flight Advisory Service to contact a flight service specialist at an AFSS to obtain weather information. Once a pilot reports his or her position and route, the specialist provides the weather information requested, including observed and predicted weather.

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--> of ARTCC controllers, and close-in aircraft are the responsibility of tower controllers. The FAA operates TRACONs at about 150 airports in the United States (FAA, 1995a). Tower controllers, who control the movement of aircraft while they are on the ground, taking off, and landing. Unlike ARTCC and TRACON controllers, who rely on radars to track aircraft, tower controllers in most cases track aircraft visually, although they also have access to radar systems. The FAA operates air traffic control towers at about 400 airports in the United States, and it contracts out control tower operations at about 30 additional airports (FAA, 1995a). The primary role of air traffic controllers is to separate aircraft from each other and, thereby, avoid collisions between aircraft while they are in the air or on the ground. Pilots—not air traffic controllers—are responsible for separating aircraft from adverse weather. FAA Order 7110.65 (FAA, 1994c) includes the following guidance for air traffic controllers with regard to weather information: Become familiar with pertinent weather information when coming on duty. Stay aware of current weather information needed to perform air traffic control duties. Broadcast a general announcement to advise pilots of the availability of hazardous weather advisories when new advisories are issued. [FAA Order 7110.65 states that controllers should direct pilots to listen to the local Hazardous In flight Weather Advisory Service broadcast or contact an FSS or AFSS to find out what the weather advisory actually says.] Solicit pilot reports of weather conditions when requested by other facilities and when specified adverse weather conditions exist or are forecast. Issue pertinent information on observed/reported weather. Provide radar navigational guidance and/or approve deviations around weather when requested by the pilot [emphasis added]. Thus, even though controllers have a general concern for flight safety that includes the impact of adverse weather, and even though they often advise pilots of hazardous weather that they may be aware of, current FAA procedures do not allow controllers to redirect aircraft movements in order to avoid such weather in the same way that they are required to redirect aircraft to avoid collisions. This situation may have arisen because controllers have never received weather information that is consistently accurate and precise enough to use as a reliable tool for directing aircraft movements. Weather data are available on the radar displays used by ARTCC and TRACON controllers, but it comes from air traffic control radars. These radars are not designed to detect weather; as a result, they are not as precise as weather radars in depicting precipitation. Moreover, during adverse weather, the weather information displayed on the radar may obscure aircraft location data, so controllers may turn off the weather information to ensure they can fulfill their primary function of controlling aircraft movements to prevent collisions. Pilots, on the other hand, often can use onboard weather radar or simply look out the cockpit window for an accurate view of local weather. Also, individual pilots have a better understanding of the impact of adverse weather on their particular aircraft than do controllers. As a result, pilots are generally in a much better position than air traffic controllers to judge the location of adverse weather relative to their aircraft and determine an appropriate course of action. Nonetheless, general aviation pilots flying under instrument flight conditions often desire and expect controllers to help keep them clear of adverse weather such as thunderstorm cells and hail. Similarly, commercial airline passengers generally expect controllers and pilots to work as a team in keeping their aircraft out of hazardous weather. Over the years, the focus of the air traffic control system on aircraft control and collision avoidance has resulted in a situation in which air traffic controllers and the FAA, which is heavily influenced by active and former air traffic controllers, seem to have developed a general cultural bias against increasing their involvement with weather and weather-related issues. This bias was repeatedly encountered by the committee as it gathered information from various FAA organizations and individuals. During bad weather, air traffic controllers may be so busy working with aircraft that they have little time to study the weather. For this reason, and because some controllers view weather information as a low priority, they may not be knowledgeable about current and forecast weather conditions in their sector. Operational procedures reinforce the message that weather is not important to controllers. Even at the ARTCCs, where meteorologists are on duty 16 hours per day, air traffic controllers do not receive a weather briefing prior to the start of their shifts. Instead, a CWSU (Center Weather Service Unit) meteorologist briefs the air traffic control supervisors after the shift starts, and the supervisors then pass along to their subordinate controllers whatever information they feel is appropriate. The timing of these briefings is set by each ARTCC, and they may not occur for an hour or more after the start of each shift. As a result, en route controllers have limited access to weather information, and they may not understand the type of weather conditions that are forecast for their sectors. This limits their ability to advise pilots about

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--> weather conditions even when they have the time and inclination to provide such advice. This can be a significant problem for general aviation pilots, who may be relying on controllers for en route weather information. Many controllers are particularly interested in receiving improved weather information to help them manage traffic flow. For example, pilots will attempt to avoid thunderstorms, and, if controllers can see thunderstorms develop on their radar screens, they can anticipate that pilots of aircraft in their area will start requesting course changes to avoid the storm. Nonetheless, controllers generally prefer to avoid increasing their workload by assuming a larger role in providing pilots with weather information. This could become a contentions issue starting in 1997 when the FAA begins installing new radar display systems for air traffic controllers. These displays will depict data from WSR-88D weather radars. Once pilots learn that controllers have access to reliable, localized weather information, it is likely that they will more often ask controllers about weather conditions. Finding: Increasing the ability of air traffic controllers to access accurate weather information would encourage them to monitor meteorological conditions routinely. Increasing controllers' awareness of adverse weather could significantly contribute to the safety and efficiency of the airways.16 Effectiveness of Center Weather Service Units During 1980 the FAA and NWS established CWSUs at the FAA's 21 ARTCCs to monitor aviation weather conditions and ''keep the controllers advised of weather conditions" (FAA, 1994e). Based on visits to several CWSUs and discussions with a variety of FAA and NWS officials, the committee believes that the utility of individual CWSUs depends to a large extent upon the personalities of the FAA and NWS personnel assigned to each ARTCC. If these personnel work well together and understand the benefit that accurate meteorological information can provide to en route operations, CWSUs can be of significant value. Even so, as discussed above, the effectiveness of CWSUs is limited because the FAA does not require controllers to receive a preshift weather briefing. CWSU effectiveness is also limited because no one in their current chain of command within the NWS (or the FAA) shares their focus on aviation weather. Organizationally, CWSUs are managed by the NWS's regional directors through an intermediate weather office in the vicinity of the CWSU. The committee encountered some managers in this chain of command who voiced little interest in monitoring the performance of their CWSUs. Instead, they relied on the FAA to determine if the CWSUs meet expected standards of performance. The FAA, however, is not a meteorological organization, and it is not structured to evaluate the meteorological performance of individual CWSUs or to suggest ways to take advantage of advances in forecasting techniques. During 1993, an FAA working group examined three options for improving CWSU effectiveness (FAA, 1994e): Close 13 CWSUs and transfer their functions to the 8 remaining CWSUs, which would be recommissioned as Area Weather Service Units. Transfer all responsibility for the CWSUs to the FAA so that the staff would become FAA employees. This option could be implemented as part of the current CWSU structure or as part of a consolidation to eight Area Weather Service Units. Contract with private weather services to obtain the services currently provided by the CWSUs. The working group initially recommended proceeding with the option to consolidate the CWSUs, but the FAA seems to have decided to maintain the status quo. Available documentation does not clearly indicate why the FAA has not implemented the working group's recommendation. Another option for improving the effectiveness of the CWSUs involves the National Aviation Weather Advisory Unit, which is part of the NWS's National Severe Storms Forecast Center in Kansas City, Missouri. During a visit to Kansas City by some committee members, the National Aviation Weather Advisory Unit impressed the committee as the most dedicated, capable, and professional group of operational aviation weather meteorologists that it had encountered within the FAA or NWS. The NWS is in the process of reorganizing the National Severe Storms Forecast Center and several other weather facilities nationwide. In 1997, this effort will result in the establishment of a new organization, the Aviation Weather Center, which will retain the aviation-related functions of the National Severe Storms Forecast Center, including those currently provided by the National Aviation Weather Advisory Unit. Under this reorganization, the Aviation Weather Center will assume management oversight of the Central Flow Weather Service Unit. As previously noted, this unit supports the FAA's Air Traffic Control System Command Center just as the CWSUs support the FAA's ARTCCs. Assigning all 21 CWSUs to the Aviation Weather Center would place the CWSUs under the direct control of the most senior official within either the FAA or NWS 16   The FAA's role in separating aircraft from adverse weather is discussed further in Chapter 6 (see Major Recommendation 7, page 56).

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--> who is focused on aviation weather and has the personal and organizational expertise to optimize the performance of the CWSUs. This approach would tie together the aviation weather community along distinct functional lines within the NWS. In addition, the Aviation Weather Center would be able to transfer new forecasting techniques and software tools that it develops directly to the CWSUs. Most importantly, this approach would centralize responsibility and authority for the performance of the CWSUs with a single, knowledgeable official who could be expected to resolve existing and future issues related to the operation of CWSUs in a timely and efficient manner. Recommendation: The FAA and NWS should improve the effectiveness of CWSUs by taking the following actions: The NWS should place all 21 CWSUs under the organizational authority of the Aviation Weather Center that the NWS is establishing in place of the National Aviation Weather Advisory Unit. The FAA should challenge CWSUs to improve the level of services that they provide. In particular, the FAA should encourage ARTCC managers and staff to use the full capabilities of the CWSUs, and it should ensure that en route air traffic controllers receive preshift weather briefings from CWSU meteorologists. Dissemination to Airport Operators Airport managers need accurate and up-to-date weather information to minimize the impact of snow and other adverse weather conditions on airport safety and capacity. In particular, timely information is essential to assemble the snow removal crews needed to keep runways open. Airports with on-site weather offices are often able to obtain tailored weather forecasts directly from local forecasters. However, most small airports have never had forecasters stationed on-site. In the future, many large airports will face this same situation as the NWS consolidates its facilities and moves some of its offices off airport property. Large airports often have on-site weather sensors and the financial resources to procure information from private weather services. Small airports, however, frequently rely on ad hoc methods to obtain the weather information needed to meet operational needs associated with snow removal, lightning, and strong winds. These methods do not necessarily involve the NWS or FAA. As a result, some airports do not always receive critical weather information in a timely or well-organized fashion. Implementation of new programs to improve the weather information available to airport operators would require additional resources, which may not be available. However, better use of existing programs could also improve the current situation. For example, as noted earlier, the FAA automatically grants licensed pilots access to DUATS. Other prospective users, including the staff of airport operators, must apply to the FAA on an individual basis for approval. Recommendation: The FAA should facilitate the ability of airport operators to acquire appropriate weather information by granting their operational staff routine access to DUATS. Training The potential effectiveness of aviation weather systems is significantly curtailed if pilots, controllers, aviation weather forecasters, flight service specialists, and dispatchers are not trained to use them properly. Thus, it is important for the FAA and NWS to develop and provide appropriate training tools for new systems and procedures that they develop. Using these tools, however, is primarily the responsibility of individual users and their employers. Training plans should include all appropriate user groups. For example, the Advanced Weather Products Generator program included a plan to familiarize air carrier pilots with its new weather products, but this plan did not include similar familiarization efforts for business or general aviation pilots (FAA, 1994a). Training on specific types of hazardous weather phenomena is especially important in areas where they occur often enough to constitute a significant threat to aviation but not often enough for local pilots, controllers, or meteorologists to become familiar with them during day-to-day operations. Realistic training is also important to avoid the complacency that can develop as a consequence of months or even years without a significant accident. Constant vigilance and attention to potentially hazardous weather are essential to minimize the occurrence of weather-related accidents. Pilots Pilots must be able to determine when adverse weather is likely to exceed regulatory requirements for flight or surpass either their skills or the capabilities of their aircraft. Many weather-related accidents take place because pilots use poor judgment in making these determinations. Many of these accidents could be avoided if pilots were more diligent in obtaining preflight weather information; if they were more attentive to meteorological conditions during flight (by observing local weather conditions and obtaining updated weather information by

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--> radio); if they had a better understanding of the preflight and en route weather information that they do receive; and if they were able to make better operational decisions regarding the weather prior to flight, en route, and before approaching an airport for landing. Improved meteorological training during initial and recurrent training for pilots has the potential to improve their ability to execute each of these tasks. Similarly, improved training for dispatchers, controllers, and flight service specialists has the potential to improve their ability to understand the weather information they receive and make better operational decisions. Experience with windshear demonstrates the potential impact of pilot training. During the last few years, the aviation community has conducted extensive training on how to detect and survive windshear events. This seems to have produced a significant reduction in aircraft accidents related to windshear. Nonetheless, avoidable accidents continue to occur as a result of anomalous windshear events and other weather phenomena that have not been the subject of a comparably intensive training effort. Initial pilot training is primarily a responsibility of prospective pilots and flight training schools. Recurrent training is generally the responsibility of individual pilots, although responsibility for advanced and recurrent training of professional pilots is shared with the companies that employ them. In addition, in order to promote the safety and efficiency of aviation, the FAA is responsible for setting standards for initial and recurrent training, including the level of weather knowledge that pilots are expected to achieve. Many pilots believe that weather is one of the most difficult and least understood subjects in the student pilot training curriculum (Lankford, 1995). As indicated by the ongoing occurrence of avoidable accidents associated with hazardous weather, traditional methods of teaching weather concepts during initial and recurrent pilot training do not always adequately prepare pilots to make consistently safe operational decisions. The classroom training of many student pilots is focused on passing the FAA's written examination, but it is possible to miss every question in the meteorological section of the written examination and still pass by doing well on other sections. In addition, many of the weather-related questions on pilot examinations focus on the ability of students to decipher the abbreviations used in standard weather messages rather than on their ability to use weather information in making safe operational decisions regarding the weather. As a result, it is not uncommon for general aviation pilots to ask flight service specialists if it is safe to fly, even though it is the pilot's responsibility to make that determination (Lankford, 1995). Recurrent training is available for general aviation pilots to improve their skills, but the experience of committee members who teach pilot safety courses indicates that too many of the pilots that really need this training do not attend the training seminars and courses that are available. Flight experience is an important aspect of training because it allows pilots to learn how they interact with adverse weather. Pilots should be able to interpret visible signs of adverse weather properly, and they should have the flying skills to avoid or escape from hazardous weather that they do encounter. For example, pilots who will be flying in mountain passes should know how to reverse course when there is minimal room to maneuver because this skill is important if they encounter adverse weather that blocks their path. Nonetheless, most student training flights occur during good weather because instructor pilots are generally reluctant to train student pilots during marginal weather conditions. Furthermore, even though major air carriers use sophisticated aircraft simulators as part of their training programs, most of the training is focused on aircraft malfunctions that most pilots will never experience rather than on weather phenomena that occur on a routine basis. Except for the windshear training that is required by the FAA, most air carriers provide their pilots with no simulator or academic training in meteorology. Similarly, there are few, if any, requirements for general or business aviation pilots to receive recurrent classroom or flight simulator training in meteorology. Specialized meteorological training is especially important for pilots who need to cope properly with unusual environmental conditions such as mountainous terrain. Low air densities reduce aircraft performance, and strong winds can create adverse flying environments. Thus, accidents sometimes occur in mountainous regions when pilots of small aircraft fail to anticipate the interaction between the terrain, the high-altitude atmosphere, and their aircraft. The general aviation accident rate for the 11 western states that the FAA classifies as mountainous is 40 percent higher than the general aviation accident rate in the other states of the contiguous United States (GAO, 1995a). In many cases, accident investigations have determined that surviving pilots or passengers saw signs of hazardous weather without appreciating the danger to their aircraft until it was too late to take corrective action (Lamb and Baker, 1995). Dispatchers Dispatchers have a responsibility to assess weather conditions in terms of regulatory requirements and company guidelines. They are also responsible for providing necessary information to assigned pilots. The training of dispatchers is a joint responsibility of individual dispatch-

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--> ers, the air carriers that employ them, and the FAA, which sets standards for training and licensing. Air Traffic Controllers and Flight Service Specialists Like flight dispatchers, flight service specialists work with pilots to assess weather conditions both prior to and during flight. It is also a common occurrence for air traffic controllers to provide en route assistance to pilots regarding weather conditions even though controllers have limited access to meteorological information. Controllers generally have less meteorological experience than flight service specialists, and controllers have other duties that limit their ability to focus on providing weather information to pilots. The FAA is directly responsible for the training and licensing of controllers and flight service specialists. For example, the FAA requires that each of its operational facilities establish an annual refresher training program that includes "unusual situations, such as weather affecting flight" (FAA, 1995b). In addition, CWSU meteorologists assigned to some ARTCCs offer voluntary refresher training in meteorology. Training of air traffic controllers focuses on reading weather products and exchanging weather-related information with pilots. New systems such as the TDWR (Terminal Doppler Weather Radar) and Integrated Terminal Weather System may make it appropriate to increase the level of meteorological training that air traffic control supervisors receive. For example, the TDWR monitors that line controllers use display straightforward alerts that require no interpretation. TDWR terminals for air traffic control supervisors, however, display a great deal of information, including six levels of precipitation, gust fronts, windshear, and microbursts. Although, the FAA provides training on new systems such as TDWR, it is not always timely and complete. For example, even though three TDWR systems were operational as of May 1995, the FAA had not yet established guidelines for training supervisors in how to use much of the information on their displays (PAI, 1995). Aviation Meteorologists Within the meteorological research community, scientific research usually takes precedence over training. The Cooperative Program for Operational Meteorological Education and Training (COMET) of the University Corporation for Atmospheric Research is a notable exception. The mission of COMET, which is funded by the NWS, Air Force, and Navy, is to improve operational weather services through advanced scientific education and training of forecasters and increased interaction between the operational and academic communities. In addition to conventional classroom training programs, COMET develops computer-based learning modules that combine voice, text, graphics, and video in self-paced modules that educate operational forecasters about advances in meteorological science. These modules are a cost-effective means to educate large numbers of geographically dispersed meteorologists without the expense of assembling them for conventional classroom training. New meteorologists generally have limited knowledge about the special needs of aviation. However, the NWS conducts its own training programs to improve staff skills. Instructor-led courses are taught at centralized locations and on-site at NWS field offices. Training Improvements One very cost-effective way to reduce the impact of adverse weather on aviation safety is to improve the effectiveness of initial and recurrent aviation weather training of (1) commercial, business, and general aviation pilots; (2) ARTCC, TRACON, and tower controllers; (3) aviation weather forecasters; (4) flight service specialists; and (5) dispatchers. Training offers great potential for near-term reductions in weather-related accidents. Improved training programs make it possible to improve the effectiveness of current systems, and it generally takes less time to develop and implement new training programs than it does to develop and deploy new weather systems. Many aviation and meteorological professionals receive initial and recurrent training at universities. Several of these universities currently offer interactive training via satellite to remote sites throughout the United States. Upgrading university educational programs could enhance the skills of many providers and users of aviation weather information. For example, increasing the availability and effectiveness of aviation meteorology courses at undergraduate and graduate institutions would enhance the overall ability of the meteorological community to understand weather phenomena of particular importance to aviation and generate accurate aviation weather forecasts. In Weather for Those Who Fly, the National Research Council recommended that "the Federal Aviation Administration, the National Weather Service, and aviation organizations should collaborate to develop a new curriculum for pilot weather education" that takes advantage of modern pedagogical technology (NRC, 1994). The committee concurs with this recommendation. Recommendation: The FAA should take the following actions to improve weather-related training:

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--> Encourage universities, flight schools, and other training facilities to focus initial and recurrent training of aviation weather users and providers on understanding and optimizing the use of available weather information. Revise federal licensing procedures for pilots, controllers, flight service specialists, and dispatchers to test more effectively the abilities of candidates to use weather information in making safe operational decisions regarding the weather. Increase the emphasis that weather receives during biennial flight reviews, safety seminars, and refresher courses for designated pilot examiners and flight instructors. Major Recommendation 2 The FAA should provide the leadership needed to develop a comprehensive national training program that improves the practical meteorological skills of users and providers of aviation weather services. Unmet User Needs As discussed above, the FAA and NWS could improve aviation weather services by addressing areas of concern related to weather observation, analysis, forecasting, dissemination, and training. In general, the areas of concern expressed in this report validate the results of other activities that the federal government has sponsored during recent years to study the needs of aviation weather users. For example, during December 1993, the FAA sponsored a National Aviation Weather Users Forum that included a wide range of aviation weather users. The 33 highest priority recommendations generated by the users forum fell into 17 categories:17 airmen education and training; AWOS (Automated Weather Observing System) and ASOS (Automated Surface Observing System); convective activity (observations, forecasts, and dissemination); dissemination of en route weather information; forecast quality for terminals and off-airport areas; icing/freezing level (forecasts, analysis, and dissemination); Integrated Terminal Weather System development; international weather dissemination; observations of cloud bases, cloud tops, and wide-spread low visibility; pilot report collection and dissemination; predictions of ground deicing effectiveness; regulatory review; runway visual range observation and dissemination; turbulence observations, forecasts, analysis, and dissemination; volcanic ash observations, forecasts, processing, and dissemination; winds and temperatures aloft observation, collection; and windshear/microburst observations. More recently, on January 9–10, 1995, the Secretary of Transportation hosted an airline safety summit. The safety summit generated seven recommendations related to aviation weather services and research: The FAA, NWS, and industry should commit to implementation of the recommendations of the 1993 National Aviation Weather Users Forum [which are referred to above]. The FAA should appoint a single senior-level manager/office to expedite implementation and coordination of aviation weather systems and service. The FAA should establish an elevated standard for airmen's knowledge of weather and the atmosphere. A data link ground-to-air communications system should be implemented to facilitate en route dissemination of graphic weather products. Icing hazards should be reduced by improving airport deicing facilities and developing new deicing fluids, ice-rejection coatings, and icing-detection systems for aircraft. The FAA should improve its processes and organizational capabilities regarding technology development and validation, setting standards, and certification. Standardization of weather products provided by AWOS and ASOS should be improved. User needs are also discussed in the National Aviation Weather Program Plan (OFCM, 1992), The Federal Plan for Meteorological Services and Supporting Research, FY 1995 (OFCM, 1994), and the Aviation Weather System Plan (FAA, 1994a). The needs described in these documents are generally consistent with those listed above and elsewhere in this report. These documents demonstrate that the federal government's effort to improve aviation weather services is not hampered by uncertainty regarding user needs. However, in order to respond to these needs, the federal government must establish and routinely exercise an effective decision-making process to resolve operational issues within 17   These categories are listed in alphabetical order. The FAA anticipates publishing an action plan during 1995 that responds to and prioritizes the recommendations of the Users Forum.

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--> budget constraints and to establish appropriate goals and priorities for aviation weather research and development. User involvement in this process is important to ensure that users adequately understand and accept new aviation weather systems during the development process. As the ASOS system has demonstrated, user acceptance can be difficult to achieve after new systems are installed if users perceive that the new systems do not meet their needs. User involvement is also important to ensure that there is appropriate balance in meeting the needs of the FAA's internal users (e.g., air traffic controllers) and its external users (e.g., air transport, business, and general aviation pilots). The committee is concerned that a recent decision by the FAA to eliminate funding for the Advanced Weather Products Generator, which is focused on improved weather products for pilots and other external users, represents a lack of focus on pilot needs. Recommendation: The FAA should take the lead in establishing and aggressively pursuing aviation weather goals and priorities that reflect the positions of other involved parties, including the following: other federal agencies and departments; other providers of aviation weather services (e.g., private weather services and state governments); and user groups, including the unions, associations, and industry groups that represent those who work with the U.S. aviation weather system on a daily basis: air carrier personnel, pilots, air traffic controllers, flight service specialists, meteorologists, and dispatchers. Near-term efforts by the FAA and NWS to improve the effectiveness of aviation weather services should focus on the urgent, unmet needs of aviation weather users, which include the following: a comprehensive national training program to improve the practical meteorological skills of users and providers of aviation weather services; advanced weather products that are relevant, timely, accurate, and easy to comprehend (e.g., graphically displayed); ground-to-air communications and cockpit display systems for en route dissemination of advanced weather products; and weather observations and forecasts that offer improved temporal, geographic, and altitude-specific resolution. The preceding section on training addresses the first of these four items. The last three are focused on what the committee has identified as the primary unmet user need associated with the current aviation weather system: a lack of widely distributed graphic weather products that allow pilots, controllers, and dispatchers to develop and maintain a consistent view of current and forecast weather conditions. This situation persists even though current technology could provide this capability. For example, The commercial air-to-ground telephone systems of some airline passenger aircraft provide facilities to connect laptop computers to ground-based commercial computer communications networks that can be used to access a variety of weather information services. Thus, passengers using modem-equipped computers can obtain up-to-date color images of weather conditions, forecasts, radar summaries, and satellite images. In most cases, these products are superior to the weather products that airline pilots can access from the cockpit. Of course, commercial systems do not face the same rigorous flight safety and certification standards as cockpit communications systems. Nonetheless, the committee urges the FAA to take the lead in deploying modern communications systems to improve the access of pilots and other users to advanced aviation weather products. In order to implement new systems swiftly, the FAA and NWS must efficiently manage the federal procurement system. The GAO determined in 1993 that the FAA's recent major acquisitions were delayed by an average of 5 years, and in almost all cases they experienced significant cost increases (GAO, 1993). For example, the FAA's Advanced Automation System "has met with billion dollar cost overruns and years of delays" (DOT, 1994). Although "the federal acquisition process takes too long, lacks flexibility and accountability, and results in products and services that cost too much" (DOT, 1994), it is possible to improve existing aviation weather capabilities quickly by relying on currently available technologies. For example, the FAA constructed and equipped the Air Traffic Control System Command Center, which includes a wide array of modern aviation weather information management and display systems, in about 2 years. This effort was comparable in scope and duration with American Airlines' construction of its System Operations Center, which includes its global operations and meteorological departments. Major Recommendation 3 The FAA should swiftly exploit current technology to provide consistent and timely graphic weather information to pilots, controllers, and dispatchers.

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