Since weather conditions can seriously restrict aircraft operations and levels of service available to system users, the manner in which weather is observed, forecast, disseminated, and used in making air traffic management (ATM) decisions is of critical importance to the operation of the United States’ National Airspace System (NAS). As the United States moves toward significantly increasing the capacity of the NAS through implementation of the Next Generation Air Transportation System (NextGen), integrating weather information (and associated uncertainty) into ATM decision-making processes is critical. RAL has been a significant contributor to this effort of developing advanced concepts of weather translation and integration.
Daily ATM planning utilizes weather predictions with forecast horizon of 12 hours and longer for high-impact weather systems, such as hurricanes and winter storms, particularly for transoceanic flights. Strategic ATM planners look for detailed information about weather systems, including storm structure, intensity, organization, location and timing, and associated forecast uncertainty.
RAL has been developing advanced concepts of using ensemble model forecasts to create probabilistic weather-related impact predictions for use today by ATM planners and for future incorporation into largely automated decision support tools. One novel approach that was developed under NASA sponsorship utilizes storm characteristics (e.g., intensity and depth) and observed pilot behavior to deviate around storms to create a convective weather avoidance field (a technique developed by MIT Lincoln Laboratory), which subsequently is subjected to Metron’s MinCut technique (a method to compute flow bottlenecks) that determines an expected capacity reduction due to the presence of storms. These procedures are applied to every ensemble forecast member in order to generate a probability distribution of potential capacity reduction for each spatial domain of interest (e.g., sectors or centers) that can be visualized as likelihood to loose a certain fraction of available airspace due to the presence of hazardous weather (Figure 1). This approach was presented by Steiner et al. (Air Traffic Control Quarterly, 2010).
During the summer of 2013 the 10-member ensemble forecasts generated by the Air Force Weather Agency (AFWA) have been accessed in real time and subjected to the capacity reduction estimation procedure outlined above. The resulting likelihood forecasts of losing a fraction of the potentially available capacity (Figure 2) have been sent to the NWS Aviation Weather Center (AWC) for use as a first guess convective storm impact prediction utilized during the Aviation Weather Testbed exercises.
The likelihood predictions of potential capacity reductions based on using the AFWA ensemble forecasts will continue and be made available again to the AWC Aviation Weather Testbed next summer as first-guess impact predictions for development of the daily Aviation Weather Statements. Significant effort will be devoted to the calibration of these capacity reduction predictions.
We will continue to use ensemble-based approaches to provide improved guidance for convective weather hazards for transoceanic flights. This effort considers exploring the concept described above to highlight potential capacity impacts due to convective storms in oceanic airspace.
Version 3.2 of the NextGen Concept of Operations (2011) provides an overall, integrated view of NextGen operations from the present through 2025 and beyond, including key transformations from today’s operations. It serves as a steering vision for the ultimate form of the NextGen end state, guiding the latest version of the NextGen Implementation Plan released in April 2013. RAL’s foundational research and transition of aviation-specific weather continues to impact planning for performance-based measures that make NextGen work—i.e., navigation, collaboration, reduced horizontal and vertical separation, traffic flow management, terminal efficiencies such as low visibility operations at airports, and separation management. RAL has taken the initiative to lead part of the effort to consolidate promising tools and methods that have potential for translation of weather constraints into ATM impact; integration into NextGen systemic representations; evaluation for system performance and feedback; and simulation of traffic flows in the presence of weather constraints for cost-benefit analyses of alternative solutions. This effort focuses on near-term R&D needed for IOC while ensuring these early steps are consistent with mid-term NextGen implementation goals. It also assures input plus feedback into the aviation weather R&D being defined for the FAA’s Aviation Weather Research Program (AWRP) and Reduce Weather Impact (RWI) programs, both part of the FAA's Aviation Weather Division.
RAL’s accomplishments fall into three areas: The AWRP, the Weather Technology in the Cockpit (WTIC) Program, and the Common Support Services–Weather (CSS-Wx) Program. Many of the accomplishments have been in the standards and performance-based metrics definition—through the RTCA, SAE, and various international data format, management, and communications bodies (weather data exchange model definition, WXXM). The AWRP continues to showcase RAL technology transition expertise through internet dissemination via systems such as Aviation Digital Data Service (ADDS, Experimental and Operational).
The growing WTIC program in RAL had many significant accomplishments. In 2013, the RTCA Special Committee 206 published two new documents—the revised “Minimum Interoperability Standards (MIS) for Automated Meteorological Transmission (AUTOMET)” (DO-252); and the AIS and MET Delivery Architecture Recommendations for weather data downlink and crosslink. RAL is a charter member of this body, interfacing with academia, industry, and government while significantly contributing to the preparation and review of these guidance documents. RAL also led the FAA Mobile MET program that defined a concept of use and infrastructure for portable device dissemination of aviation weather. This program is a multi-year effort that will eventually prototype a weather dissemination tool for mobile devices that might be used to further explore pilot and controller needs. In 2012, RAL led a significant simulation study of the use and display of oceanic weather information in the FAA William J. Hughes Technical Center (WJHTC) Research Cockpit Simulator in Atlantic City (Figure 3). The FAA Technical Report documenting results of the simulation was published in FY13. This effort will lead to further oceanic weather R&D with uplink of information to actual passenger flights (Figure 4). RAL also contributed to an SAE Aerospace Recommended Practice document on cockpit display of data linked weather information. This document is the result of over three years of collaborative effort with industry, government, and RAL participation. The symbology defined here will form the basis of cockpit weather displays in the near- and far-term (out to 2025).
Finally, the RAL-led NNEW program transitioned to a procurement action for the FAA and assumed a new moniker, the Common Support Services – Weather (CSS–Wx) Program. RAL continues its interface with the JPDO and other government-industry fora to update JPDO planning on an annual basis.
Future integration planning and implementation for the mid-term NextGen vision will require meaningful collaboration with recognized leaders in national airspace system performance and flow constraint impact. RAL is pursuing joint efforts with the Mitre Center for Advanced Aviation System Development (CAASD) and industry that will potentially conduct laboratory evaluations of one or more weather translation-to-impact capabilities, integrated with prototype ATM decisions support tools. Other initiatives through FAA sponsorship will explore first-order integration of weather information to support decision making on the flight deck as well as collaboration with air traffic managers and controllers. We will document the results of the investigated translation capability algorithms and of the integration of the information into ATM decisions support algorithms, in the context of the NextGen mid-term vision contained in the NextGen Implementation Plan.
Under an Aviation Weather Cooperative Agreement (AWCA) with NOAA, RAL continues to facilitate collaborative work on weather integration and to transition that work from research to operations across federal agency lines for NextGen interim capabilities. The collaborative effort in FY13 has been defined in general terms to include turbulence, ceiling and visibility, and in-flight icing with a specific focus on developing and using human-over-the-loop (HOTL) forecast techniques.
For in-flight icing: Activities centered on advances surrounding the Interactive Correction in 4 Dimensions (IC4D) system. IC4D runs on a workstation at NCAR and is monitored to ensure it is operating properly and that the output looks correct. We update the system as needed to keep in pace with that being used at AAWU. Additionally, work has continued to improve the Forecast Icing Product (FIP), the output of which is input into IC4D for analysis and adjustment.
For turbulence: Accomplishments included support activities for the development and testing of a global turbulence forecast product based on the CONUS GTG for eventual WAFC implementation, and publication of a collaborative article for Geophysical Research Letters which reviewed the state-of-the-art understanding of the nature and sources of atmospheric turbulence for aviation.
For ceiling and visibility: R&D was directed toward forecast methods that could be used in an automated ceiling and visibility forecast system (CVF), including work focused on development of a self-adjusting method to determine optimal probability thresholds needed to derive deterministic forecasts from probabilistic forecast data. The advantage of such an algorithm will be its ability to self-adjust to accommodate seasonal and year-to-year variability. Better thresholds are expected to yield better deterministic forecasts.
The NOAA Aviation Weather Cooperative Agreement will continue to facilitate limited collaboration between RAL and the NWS with its focus on HOTL, and within the general framework described above.
RAL participated in many of the outreach venues available to further weather R&D, harmonization, and integration into ATM decision support tools. Notable events included new technology workshops sponsored by the FAA, NASA, and the Air Traffic Control Association (ATCA).
Presentations that were specifically focused on the weather integration problem were given by RAL staff at the FAA/NASA/ATCA New Technologies Workshop in Atlantic City, NJ in May 2013, and the AMS ARAM Conference in January 2013. RAL also participated in FAA and industry advisory committees such as the RTCA, SAE G-10 (weather displays on the flight deck), and the Friends and Partners of Aviation Weather (FPAW). We provided expertise on weather technologies as well as received feedback from industry and government on how we are meeting respective user needs.
RAL will participate in the 2014 ATCA/NASA/FAA New Technologies Workshop and the ATCA Annual Meeting, as well as continue to play a critical role in RTCA and SAE for a. RAL will continue to participate in as many team partnerships as feasible to ensure and support a comprehensive transfer of our technology to NextGen implementation plans.