Integrating Weather into the Future Air Transportation System

The primary goal of the Next Generation Air Transportation System (NextGen) is to address and meet the rapidly changing needs of the National Airspace System (NAS). Providing accurate, timely weather information at the temporal and spatial scales required by aviation decision makers is fundamental to NextGen's success in achieving capacity, efficiency, and safety goals. Aviation weather represents the majority of the R&D effort at NCAR's Research Applications Laboratory (RAL). For over 25 years, RAL's applied research has focused on applying sound science to aviation weather information and product development.

Improved weather forecasts, plus a shared source of decision support information for NAS decision makers, are crucial elements of achieving the goal of reducing the weather impact to NextGen. The first step, though, is establishing a clear understanding of the impacts that have the most affect on NAS efficiency and capacity. The most visible impact to us all is "delays," both airborne and ground, affecting both airplanes and people. Delay translates to operational cost for the airlines, and lost productivity for the users of the system–people and cargo. Clearly, as shown below, weather has the most affect on the NAS air traffic management (ATM) impact.

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Second, since weather information is complex in terms of spatial and temporal definition and its relationship to a 4–D flight profile, it must be effectively integrated into the NextGen decision support process. Without effective integration, benefits will be elusive. NextGen will include human in–and–over the loop decision support processes as well as fully automated machine–to–machine interactions. These considerations demand that weather information be clearly presented (to both human and machine) and unambiguous. Since weather and the NAS response to weather will always be uncertain, NextGen will introduce and make extensive use of probabilistic forecasts and response as risk is managed as opposed to avoided. That is, affected airspace will have some degree of permeability in NextGen and not simply closed as in today's NAS.

Third, and very important, weather requirements to support decision making must be clearly understood. Defining user needs for weather information must change to defining needed decisions and in a top–own fashion identifying the weather information required to support those decisions.

The FAA's Aviation Weather Office (AWO) operates four key programs which play critical roles in the integration of weather into DSTs.

Aviation Weather Research Program (AWRP): The program develops new technologies to provide weather observations, warnings, and forecasts that are accurate, accessible, and efficient. RAL R&D and product development address all known aviation weather hazards:

Turbulence
In-Flight Icing
Convection
Winter Weather
Ceiling and Visibility

Reduce Weather Impact (RWI): The RWI Program addresses improved forecasts, and provides weather forecast information tailored for integration into traffic management decision support systems. Some of this work starts with identification of the ATM impact of interest, and then translating weather into metrics associated with that impact. One example system that translates a large amount of weather data into a significant safety and delay impact is the Weather Decision Support for Deicing Decision Making (WSDDM) System. Here, airport snowfall rate in terms of liquid water content is translated into deicing fluid application procedures and aircraft holdover times. RAL scientists are involved with the weather translation to impact problem in a number of projects led by industry and sponsored by NASA and the FAA. Metron Aviation is one example.
Weather Technology in the Cockpit (WTIC): The Weather Technology in the Cockpit (WTIC) Program seeks to ensure the adoption of cockpit, ground, and communication technologies, practices, and procedures that will provide pilots with shared and consistent weather information to enhance common situational awareness, plus engage the aircraft as a "node" that autonomously exchanges weather information with surrounding aircraft and ground systems.
NextGen Network Enabled Weather (NNEW): The NextGen Network Enabled Weather (NNEW) develops the standards necessary to support universal user access to needed weather information. It enables the seamless access to standard weather data sets by all NextGen users via the 4–D Weather Data Cube.

RAL has extensive experience in developing and fielding decision support systems for aviation, starting in the mid–eighties with the highly successful Terminal Doppler Weather Radar (TDWR) system. We currently work with the FAA, NASA, the National Weather Service, and industry on state–of–the–art methods we can use to integrate weather hazard and environmental information into decision support systems for NextGen. RAL scientists participate in a very important piece of work that is sponsored by the NASA Ames Research Center, modeling weather hazard information mathematically and translating the resulting models into ATM impact metrics such as aircraft flow rates through flow constrained airspace (FCA) volumes. This is the first step towards defining decision support tools that will become part of systems for NextGen.

Because of its highly diversified staff and extensive experience working with aviation end–users, RAL has a complete understanding of how integration varies by type of hazard or environmental information. For example, the in–flight icing hazard affects traffic flow and safety of flight at altitudes less than FL200 which is quite significant for low–performance general aviation. It can be modeled as a hard, soft, or no constraint at all depending on aircraft capability. However, it can significantly impact air traffic of all types during approach and landing, which in turn can cause delay well upstream and downstream of the actual hazard.

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The above figure illustrates the simple translation from a 4–D Current Icing Product (CIP) to hard/soft constraints, the relative "hardness" of which is defined by aircraft type and equipage.

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The above figure goes further by defining a contingency table in two dimensions, aircraft class and weather event type. Airways are color coded for either human or machine use to define appropriate flows through the FCA.

The turbulence hazard can be penetrated safely by aircraft properly prepared for the encounter in most cases; therefore, it too can be a soft, hard, or no constraint depending on type of operation and pilot and/or airline preferences. Turbulence is currently regarded as a hard constraint if it is severe or greater. Similar to the icing example above, the following figure illustrates the translation of Graphical Turbulence Guidance (GTG) to relative constraint hardness.

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And finally, convection is integrated quite differently when considering the vertical extent of the hazard. That is, a convective blob is mostly 2–D–pilots avoid it laterally and the decision support system has to account for this. Also, Nexrad imagery commonly used by pilots and traffic managers has latency and is really a surrogate for the real hazards–turbulence, icing, lightning. And finally, pilots who have access to real–time airborne radar imagery will tactically and unpredictably avoid convection on their own. All these factors mean that any strategic planning around an area of convection must be done using sound and credible weather information that minimizes uncertain tactical pilot response. One potential approach to the translation of convection to ATM impact using ensembles can be found here

The above illustrates the concept of use for the FCA as it might integrate with the NAS. Routes within the FCA are defined by an FCA planning DST; routes outside the FCA are determined by routing preferences of the user.

FACET simulation with both hard and soft constraints.

NASA's Future ATM Concepts Evaluation Tool (FACET) is used to further understand how aircraft flows are impacted by FCAs that are defined by actual weather, translated to varying soft and hard constraints. Above we illustrate one of many FACET realizations to illustrate the concept.

The NASA Ames Weather Translation to ATM Impact Study will leave NextGen planners with a better understanding of how weather impacts NASA's performance metrics, and provide valuable experience with the use of probabilistic and deterministic weather constraints. These outcomes will become the foundation for the development of decision support tools that will be used by both human and machines as NextGen evolves.

Aviation Applications Projects

Short Term Convective Storm Forecasting

In-Flight Icing

Winter Weather for Aviation

Aviation Turbulence

Automated in situ turbulence measurement and reporting methods using commercial aircraft
In cloud turbulence detection from NEXRAD radars (NTDA)
Airborne remote turbulence sensing techniques
Aviation turbulence forecasting (GTG and GTG2)
Aviation turbulence forecasting (GLOBAL)
Characterization case studies of aviation scale turbulence

Ceiling and Visibility

Dissemination

Integration

Satellite Applications

Terminal Area Weather

Note: full phone: 303 - 497 - XXXX | email addresses end in "@ucar.edu"

Primary Contacts

CARMICHAEL, Bruce | AAP DIRECTOR | ph: 8406 | email: brucec
BARRON, Bob: | AAP DEPUTY DIRECTOR | ph: 8410 | email: bob
POLITOVICH, Marcia | AAP DEPUTY DIRECTOR | ph: 8449 | email: marcia