Description This paper describes the conceptual model which applies weather observations, analyses, and forecasts of meteorological parameters into aviation specific and operationally-meaningful, weather-related values of NAS constraint and operational impact conversion. The paper consists of the following sections: An initial high-level definition of Weather Translation Amplification of definition terms Examples of Weather Translation A Weather Integration Context diagram A brief summary of key characteristics of Weather Translation
ATM-Weather Integration ATM-Weather Integration starts with the collection and dissemination of observed, analyzed or forecast weather information. That information is then translated into either relevant, standardized threshold events (i.e. the wind shift at an airport causing the change of runway configuration) or characterizations of weather-related NAS constraints (i.e. severe turbulence or thunderstorms). Responsibility for these first two components belongs to the meteorological community, with translation in particular requiring input from the ATM community.
Threshold events and NAS constraints are next converted into potential NAS state changes (i.e. a reduced arrival rate due to lowered visibility) in the case of threshold events or ATM impacts (i.e. reduced flow through a sector due to thunderstorms) in the case of a characterized weather-related constraint. Finally, decision support tools or processes take the NAS state change and ATM impact information and devise solutions which optimize the flow of air traffic. The ATM community is responsible for the development of systems which turn threshold events into NAS state changes and weather constraints into ATM impacts and generate optimal solutions when those impacts cause demand/capacity imbalances.
Weather Information In the NextGen system, it is assumed that most weather information will come from the 4-D Weather Data Cube (Cube), and that all weather-related ATM decisions will be made after considering weather forecasts from the subset of the Cube known as the Single Authoritative Source (SAS). Additionally, it is possible for weather information to feed directly into decision support tools without being translated into constraints or converted to ATM impacts.
Weather Translation This capability takes raw weather information and translates it into threshold events or NAS constraints. The term threshold event applies to a situation in which a non-hazardous atmospheric parameter such as cloud ceiling height, visibility or wind speed crosses a regulatory or operational threshold and may result in an associated change in the state of the affected NAS element, normally an airport. Examples of state changes for an airport include a runway configuration change, landing minima change, or arrival/departure rate change.
With respect to weather, NAS constraints are meteorological phenomena which are hazardous to aircraft. In the airport environment, these typically include hail and lightning, turbulence/winds/wind shear which exceed aircraft safety operating limitations and freezing and frozen precipitation occurring at rates which exceed aircraft operating capabilities. The same phenomena affect aircraft operations in the en route airspace, with freezing and frozen precipitation being replaced by icing which exceeds aircraft operating limitations. For reasons of safety, aircraft do not operate to, from or through NAS elements known to contain hazardous weather. Because aircraft avoid airports or airspace containing these hazards, the efficiency of the ATC procedures in, and overall capacity of, those airports and airspace are reduced.
ATM Impact Conversion ATM Impact Conversion functionality takes information from Weather Translation and converts it into potential NAS state changes (in the case of threshold events) or capacity impact (in the case of characterized weather-related NAS constraints). In every case, safety is paramount and the major factor considered by the functionality as it attempts to measure the effects of the constraint, and the most accurate and up-to-date estimate of demand is used prior to determining the magnitude of the impact. In addition to weather constraints, this functionality can ingest non-meteorological constraint information such as Special Activity Airspace (SAA) and runway closure information and then process it identically.
ATM Decision Support These tools use the NAS state changes or impact analysis results from ATM Impact Conversion functionality in developing traffic management plans, strategic through tactical, that suggest the best operating strategies to deal with forecast changes of state of NAS components or that best mitigate the effects of the forecast set of constraints.
Summary Translation, Conversion, and Decision Support may reside in a single tool, or as two or three individual tools working in concert with each other. At this level, there is very little human involvement other than strategic oversight of decisions and overall performance. In these fully automated DSTs, interpretation of weather will not be required by the user, but the user will be able to drill down into the decision if desired.