Advanced Aviation Weather Products
Now and in Our Future
Air Line Pilot, May/June 2002, p.16
By Dave Fritts
Airlines, flight and cabin crew members, and passengers are well aware of the effects of weather on air travel. Bad weather often results in delayed or canceled flights, missed connections or missing baggage, airport congestion, and unexpected overnight stays. Severe weather is occasionally implicated in in-flight injuries and airline accidents and incidents. Whereas passengers are usually only inconvenienced by weather, airlines measure weather-related losses in the billions of dollars. Garry Hinds, weather center operations manager for United Airlines in Chicago, says, "The large majority of irregular airline operations are weather-driven." Given the reality of weather risks, airlines and other entities continue to explore how better weather information technology can improve weather knowledge and awareness and lessen the personal and corporate costs of weather in aviation.
Advanced weather forecasting
The state of the art in weather forecasting has advanced rapidly in recent years, propelled in part by ever faster computers, now approaching a million times the speed of the first Cray 1 supercomputer introduced a quarter century ago. Additional improvements have come about through a better understanding of the processes underlying forecast accuracy. The atmosphere is a fluid system, and a weather forecast represents a future state of the atmosphere, which can be approximated several hours to days into the future through the use of well-known equations for describing fluid motion. The challenge is in describing all of the various processes influencing weather, as many important processes occur on very small scales.
Typical low- and high-pressure systems are hundreds of miles across and are described well in a weather forecast model that has a spatial resolution of 20 miles, corresponding to the best resolution the National Weather Service (NWS) used until very recently. But many other weather phenomena, such as frontal zones, sea breezes, and airflow over and around terrain, are too small to be described adequately by such low resolution. Just as a finer mesh in a fishing net permits the capture of smaller fish, a finer grid resolution in weather forecasting allows the description of smaller-scale processes that may nevertheless have large influences on weather in the future.
High-resolution forecasting has been used in forecasting weather for such specialized events as the 1996 Atlanta Olympics (1.2- and 5-mile meshes), terrain influences on weather around major airports, and pollution and dispersion studies in the Los Angeles basin and elsewhere, and in various research studies of severe weather effects. The NWS, the military, and one commercial entity, Foresight Weather of Boulder, Colo., are now generating similar high-resolution forecasting nationwide.
With current forecasting resources, site-specific or route-specific forecasts for the airlines are now practical and could dramatically improve airline and pilot awareness of, and responses to, forecast significant and severe weather. Very high resolution forecasts of significant weather around major airports (as high as 0.6-mile resolution), for example, could aid in traffic management and flight operations, save fuel, and lessen, at least, significant weather effects on the air transportation system. Advanced techniques are likewise available or being developed for forecasting turbulence accompanying mountain waves, convection, and windshear, while advanced cloud moisture descriptions enable state-of-the-art precipitation and icing forecasts. Parallel advances have occurred in presenting weather and forecast information, though the airline industry has yet to fully use these capabilities.
Benefits of better weather forecasting
Several airlines equip in-house meteorologists and dispatchers with graphics workstations that can display a spectrum of weather information typically originating with the NWS, but often packaged by other vendors. Currently, pilots receive radar summaries, weather depiction charts, flight-level winds and temperatures, and text-format weather briefing information with severe weather indicators before flight. In flight, pilots have access to TWEBS, PIREPS, and other updates via radio or ACARS.
Essentially all flight-specific weather and forecast information is provided by in-house meteorologists, whereas flight-specific graphical aids are limited or nonexistent. Yet such forecast information could be made available to dispatchers and pilots in many formats. This would be of enormous potential benefit to the airlines because superior weather information and forecasts would almost surely result in better traffic management, fuel savings, reduced flight hazards, and fewer in-flight injuries. Given the magnitude of the airlines’ weather-related losses each year, even a modest fractional savings could contribute significantly to better profitability.
Airlines are poised to benefit from existing weather forecasting technologies in several ways. Flight planning and traffic management would benefit from enhanced knowledge of significant weather at major hubs having implications for congestion and delays throughout the air transportation system. Hub forecasts achieving 0.6-mile (or better) resolution can describe significant weather, like squall lines, thunderstorms, ceilings and visibility, and strong wind shifts far more precisely than previously possible, enabling both anticipation of traffic management requirements and specific flight routing in and around significant weather.
High-level graphical displays would provide dispatchers with real-time, two- and three-dimensional (2D and 3D) views of weather, hazards, and air traffic. Pilots could benefit from improved flight-specific (and route-specific) forecasts of turbulence, icing, and flight-level winds. Flight planning and routing would benefit from significant or severe weather advisories at airports where specific weather, like fog in San Francisco, snowstorms in New York, or frontal passage in Chicago, might affect landings, require deicing, or cause diversions to other airports. As airline weather needs evolve, high-level graphical information can even be made available in the cockpit. Indeed, several companies are providing, or planning to provide, weather information in the cockpit via ground-station datalinks or satellite communication using either request-and-answer or broadcast-only technologies.
Many groups are working on meeting a diversity of forecasting and weather information needs. A number of organizations now provide routine forecast and weather information derived from NWS forecasts and data collection in web-based formats. One specific to civil aviation is the ADDS website, http://adds.aviationweather.noaa.gov/, which the FAA funds and which is familiar to many pilots. It displays aviation-related products ranging from METARS and PIREPS to satellite imagery, radar maps, and various products derived from NWS forecasts.
Extensive research is being done to develop better methods for forecasting turbulence, icing, and significant or severe weather. Other efforts are yielding advanced methods for displaying forecast and observed meteorological data in a graphic format. In several areas, the benefits are available now—for example, new technologies have been developed for forecasting turbulence and icing and for enhanced presentation of forecast and observed weather information to airline personnel.
The Naval Research Laboratory (NRL), in its support of NASA research flights, is making turbulence forecasts based on advanced descriptions of mountain waves. Likewise, current workstations and software (for example, the AWIPS workstation developed by the NOAA Forecast Systems Laboratory, or FSL) support the display of multiple 2D and/or 3D data sets and enable meteorologists and flight dispatchers to view multiple data sets simultaneously. With these motivations, several airlines are trying to define advanced flight planning tools that will integrate current aircraft situational display (ASD) information from ATC, flight plan and weather forecast information, NOTAMs, ground-to-air communications, and analysis tools to help mitigate in-flight risks, save fuel, and reduce other costs.
The need for advanced planning and analysis tools has prompted developments in many areas. The NWS currently creates hourly forecasts with its RUC model (currently at 25-mile resolution), which provides very good descriptions of flight-level winds, extending typically to 3, but occasionally to 6, 12, or 24 hours.
Foresight Weather (FSWX) is merging state-of-the-art research activities with user-specific applications. FSWX scientists conduct substantial research each year to develop improved forecasting methodologies with internal and federal research funding. The result is four national forecasts daily extending from 2 to 10 days, two of which, at 6- and 7-mile resolutions, offer airlines the potential for detailed flight-specific forecasts of meteorological conditions as well as advanced icing and turbulence forecasts. Advanced icing forecasts are based on a research-grade description of cloud microphysics and precipitation. The turbulence forecasts derive from a partnership with NRL scientists using the mountain-wave turbulence model and developing extensions to other major sources of flight-level turbulence (primarily convection and windshear). Examples of vertical and horizontal flight cross sections from the FSWX national model for a hypothetical flight from Denver to Chicago on March 25 displaying winds along the flight track, as well as turbulence and significant convection flight hazards, are shown in Figures 1 and 2. Current technology allows dispatchers or airline meteorologists to customize such cross sections and make them available for every flight nationally or globally every day.
Another benefit of current technology is the potential for very high resolution forecasting around major airline hubs that suffer frequent congestion and/or significant weather. Such local forecasts extending from 50 to 100 miles around a hub (and achieving resolution as fine as 0.6 mile) describe significant weather much more accurately than is currently possible at the resolutions that the NWS and FSWX use for national forecasts. Such very high resolution forecasts would enable airline dispatchers and ATC to plan and coordinate traffic more fully and guide pilots around significant flight hazards. Indeed, such forecasting improvements have already been demonstrated on a number of occasions. Likely benefits to airlines would include better scheduling, fuel savings, advance knowledge of deicing needs, less potential for in-flight injuries, and reduced weather-related costs to airlines.
Hub forecasts have been implemented in a research or test mode by the National Center for Atmospheric Research (NCAR) at Hong Kong, by the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma in partnership with American Airlines, and by FSWX at Los Angeles and Chicago in tests on behalf of United Airlines, among others. In the case of Chicago during significant convective activity, the FSWX mesoscale forecast provided a more precise description of convection intensity and precipitation than was available from other sources (see Figures 3 and 4). Yet airlines have not evaluated such capabilities fully nor determined how to share the costs of such forecasting and flight planning tools. This is due, in part, to the gulf between the technology that the airlines currently use and what is now available. But this gulf will close when airlines recognize the potential savings and commit to a new suite of fully integrated weather forecasting and flight planning tools.
Future weather forecasting
Research and development efforts that have propelled advances to date will also ensure more-accurate forecasts and more-functional systems in the future. FSWX will soon extend to other major turbulence sources the current state of the art in turbulence forecasting, namely, mountain wave turbulence forecasts based on NRL research. New data sets from a variety of sources will likewise provide more-accurate initial conditions for weather forecasts, thus presumably increasing accuracies hours to days into the future. Examples include more-precise ocean-surface wind measurements (which define surface pressure systems more precisely) where no local measurements are available, better cloud and precipitation sensors using radar and satellite technologies (defining frontal systems and convection more completely), and upper-air measurements of pressure, temperature, and winds by airlines and unmanned aircraft (now a rapidly developing technology).
Future forecasts will likewise apply to the entire globe the same resolution currently applied across the continental United States. The very ambitious Frontier research project in Japan is addressing the coupled atmosphere/ocean-hydrology system and is now installing a computer named the "Earth Simulator," which is capable of 10–100 times the computations of current supercomputers in the United States. The goal of this project is to describe weather (and the hydrological cycle) with 3-mile resolution across the entire globe. The NWS, the military, and FSWX have similar plans to increase model resolution globally, which will yield improved forecasting accuracies that will further enhance flight safety and efficiency over the United States and internationally. Improvements in ground-based and cockpit displays of weather information, as well as space-based navigation and communication systems (for example, the Future Air Navigation System, or FANS, under development by Boeing), promise to bring more and better weather information to dispatchers, ATC, and pilots as these technologies mature.
In summary, advanced forecasting capabilities are now available and can contribute to airline efficiency and safety in two broad areas. Advanced weather forecasts alone would provide advance warning of significant or severe weather (affecting ground operations, deicing requirements, and flight scheduling, etc.) and lessen the risk of inflight hazards (icing and turbulence). As one component of an integrated flight planning, communication, and navigation system, advanced weather information would further enable streamlined flight planning and traffic management, save significant amounts of time and fuel, and likely contribute to fewer inconvenienced passengers and more profitable airline operations. Increased benefits will also accompany improved global forecasting capabilities as technology and our descriptions of weather and its influences advance. Importantly, airlines could benefit from such technologies immediately, but are generally not doing so, because of a lack of awareness of available forecasting capabilities and their current desire to minimize costs wherever possible.
Dave Fritts received a Ph.D. in physics from the University of Illinois in 1977. Following postdoctoral appointments with NCAR and the NOAA Aeronomy Laboratory, he spent 15 years as a professor at the Universities of Alaska and Colorado and 7 years in corporate research. He founded Colorado Research Associates, a division of Northwest Research Associates, in 1977 and is a founder and president of Foresight Weather.
Activity Dealing with Weather and Environmental Hazards
Several ALPA-member pilot safety volunteers who have backgrounds and strong interests in aviation meteorology and environmental hazards provide their talents under the auspices of the Association’s Air Traffic Services Group, through its Aviation Weather Director. Four major areas are currently covered:
Weather detection and dissemination
"Friends/Partners in Aviation Weather" conducts an annual forum for industry/government representatives to discuss common aviation weather interests and concerns, research and development plans, and safety issues involving weather detection and dissemination. ALPA co-sponsors the annual forum, and ALPA representatives participate throughout the year to ensure that pilot aviation weather interests and concerns are properly addressed. Smaller meetings and teleconferences are called whenever the group identifies specific needs during the year.
Volcanic ash and aviation safety
ALPA began to play an active role in detecting volcanic ash and disseminating that information shortly after Mount St. Helens erupted in 1981. Since then, the Association has taken the lead in providing operational input to International Civil Aviation Organization reporting standards and provides operational guidance for detection and dissemination strategies at the national level. The Association is particularly involved in evaluating standards for using ash detection by satellite and is an invited member of an industry/government committee that the U.S. Office of the Federal Coordinator for Meteorology chairs. ALPA members interact with ICAO, the FAA, the United States Geological Survey, and the National Weather Service to ensure that aviation safety interests are considered whenever volcanic activity threatens aviation navigation routes or airports throughout the world.
Inflight turbulence risks
Under the FAA’s Safer Skies Program, the Commercial Aviation Safety Team (CAST) commissioned the Turbulence Joint Safety Analysis Team (JSAT) to study the continuing high rate of air carrier turbulence incidents and accidents. This team analyzes turbulence incidents and accidents, develops intervention strategies to correct deficiencies, and ultimately recommends strategies to the Turbulence Joint Safety Implementation Team (JSIT). The JSIT further develops and recommends that strategies be implemented, through CAST, to carriers, manufacturers, and regulators and, as its goal, hopes to eventually reduce commercial air carrier inflight turbulence encounters and injuries by as much as 80 percent by 2010. ALPA has co-chaired both the JSAT and the JSIT with FAA and NASA representatives and has provided three additional safety/technical representatives to each of the teams. The Turbulence JSAT completed its work in 2001, and the Turbulence JSIT work should be concluded later this year.
Weather information in the cockpit
ALPA has been participating through RTCA Special Committees, chartered at the request of the FAA, in studying and developing operational performance standards for electronically linking both textual and graphical weather information to the cockpit and displaying it there. Text and graphics are now available for carriers using the ACARS messaging system through ARINC. At least one carrier is now testing color graphical weather displays, and integrated systems could eventually be available as a result of these and other research efforts.
—Bill Phaneuf, ALPA Senior Staff Engineer