Advisers to the Nation on Science, Engineering, and Medicine

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M.Alberts is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Wm.A.Wulf is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V.Fineberg is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M.Alberts and Dr. Wm.A. Wulf are chair and vice chair, respectively, of the National Research Council

www.national-academies.org

Increasing aircraft volume in U.S. airspace presents a critical problem for air traffic flow and management. As a result, the Federal Aviation Administration (FAA) is continuously planning future air traffic control systems and protocols. Improved forecasting of severe convective weather is a critical part of this planning. Knowledge of the three-dimensional location and intensity of hazardous convective weather 2 to 6 hours ahead is central to selecting air traffic routes that will support the planned traffic with little or minimal weather delays or diversions. For traffic flow management to operate based on forecasts of convective weather, the entire aviation operations community needs to have a high-level of confidence in the forecasts and a common understanding of how they will affect operations. One of the key limitations in applying these forecasts for traffic flow management is the inherent uncertainty and complexity of making temporally and spatially well-resolved short-term forecasts (2 to 6 hours) of convection.

To help identify the limitations of convective weather forecasting and begin a dialogue on potential steps forward, the FAA asked the National Research Council (NRC) for assistance. In response, the NRC formed the Committee for a Workshop on Weather Forecasting Accuracy for FAA Air Traffic Control, which convened a 2-day exploratory workshop on June 4–5, 2002, in Washington, D.C. (see Appendix D). The workshop was a forum to address the complex issues related to research needs for convective weather forecasting. In particular, the workshop discussions explored the present and future potential in meeting required convective forecasting accuracies and how those forecasts could have greater utility to air traffic controllers, airline dispatchers, and pilots. Further, because it was indicated that the desired forecasting accuracy may not be achieved in the near future given existing

research activities, workshop participants generated a prospectus for a study to examine what is needed to reach the FAA requirements.

The first session of the workshop provided an opportunity for the operational and user communities to frame the problem. Presentations focused on identifying current activities for which improved understanding of convective weather would assist traffic flow management. The second session involved members of the research community who were assigned the task of identifying current and potential future research activities that could lead to improved 2- to 6-hour convective forecasts and more effective presentations of these forecasts. The FAA provided the following questions to help guide the presentations during the workshop’s second session:

1. What approaches and strategies will be most effective to get an accurate 2- to 6-hour forecast of areas of convection for aviation use in the next 5 to 10 years? (Accurate means a desired false alarm rate (FAR) of =0.20, a desired probability of detection (POD) of =0.80, a maximal FAR of 0.30, and a minimal POD of 0.60.)

2. What specific scientific enabling capabilities are needed to realize these gains and when will they be available? For example, what improvements in observations, algorithms, analyses, and numerical modeling are likely to yield the best results? What are the major gaps in the current research and development activities that need to be addressed?

3. What is the most appropriate way to present the forecast in an operational setting?

• Consider the two main uses are flight planning and traffic flow management.

• Consider how the forecast will be developed and presented (i.e., purely probabilistic or deterministic).

4. How will we know when we are done? What verification scheme makes the most sense from an aviation perspective?

Many workshop participants opined that the goals set by the FAA for FAR and POD were overly ambitious and, in fact, ill posed. That is, improvement in skill as measured by metrics such as FAR and POD do not necessarily translate into increased value for the end user owing to numerous mitigating influences (e.g., constraints on the overall air traffic system, nonweather impacts, and industry-government politics). In addition, such metrics, which are perfectly suited for large-scale weather features, do not

apply to spatially irregular and highly intermittent convective phenomena. An alternative set of objectives was alluded to by James Washington, of the FAA, during the first session of the workshop (see Chapter 1).

During the final session of the workshop, the committee and guests identified issues and focused research topics that need to be addressed in any follow-up activity or study.

The three chapters of this report correspond to the three sessions of the workshop. This report was prepared by the committee and recounts the discussions that took place during the workshop; the workshop format prohibited the development of findings or recommendations.

The committee thanks everyone who helped plan or who participated in the workshop, especially the invited speakers: Lance Bosart of the State University of New York at Albany; Peter Challan, James Washington, Jack Kies, and Richard Heuwinkel of the FAA; Russell Gold of the Air Transport Association; William Cranor of US Airways; Mark Phaneuf of AvMet Applications; Barbara Brown and Andrew Crook of the National Center for Atmospheric Research; Fred Foss of the Aviation Weather Center; Jack Hayes and Alexander MacDonald of the National Oceanic and Atmospheric Administration; Ross Keith of the Australian Bureau of Meteorology; and Joby Hilliker of Pennsylvania State University.

Steven F.Clifford

Chair

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report:

Although the reviewers listed above provided constructive comments and suggestions, they were not asked to endorse the report’s conclusions or recommendations, nor did they see the final draft of the report before its release. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.