Weather translation refers to the process of transforming raw weather observations and forecasts into expressions of weather that are operationally relevant to the NAS. The best known example of a weather translation is the Weather Avoidance Field (WAF), an algorithmic transformation of observed and forecast convective weather information into the likelihood that an aircraft will deviate from its planned trajectory upon encountering the convective weather. A WAF is an example of the class of weather translation currently known as a NAS constraint.
The other class of weather translation is known as a weather event. This type of weather translation takes observed or forecast weather parameters such as wind speed and direction, cloud heights and visibility and relates them, based on adapted, user-specified meteorological conditions, to different operating states at the affected NAS element (airport or airspace). When the value of those parameters crosses an operationally-relevant boundary, a weather event is said to have occurred. An example of a weather event is when the visibility lowers from six or more miles to below three miles, the point that an airport’s operating state changes from enabling the use of visual flight rules (VFR) to requiring the use of instrument flight rules (IFR).
Weather Event Detection and Advisory is an envisioned capability that evaluates specific atmospheric factors such as ceiling, visibility and wind conditions, and identifies weather events that may impact terminal flight operations and affect airport capacity. Airport capacity measures, which necessarily include the terminal airspace, are expressed in terms of airport arrival rate (AAR) and airport departure rate (ADR).
There has been much research and product development of decision support tools (DSTs) that use automation to generate AARs and ADRs, which take into consideration many factors including runway configuration, staffing levels, arrival and departure flows, expected traffic demand and of course expected weather conditions. These rates may need to be adjusted by considering a variety of key meteorological (e.g., cloud ceiling, airport and terminal visibility, airport and terminal wind speed and direction, and precipitation types) and non-meteorological parameters (e.g., fleet mix, staffing). Thus, WEDA does not attempt to generate an ADR or AAR but instead provides the traffic managers and supervisory personnel with reliable forecast of weather events, including both short-term and long term forecasts with uncertainty, that can be used cognitively or by automation to estimate ADRs or AARs.
In this paper, we describe WEDA as a concept that transforms raw weather into potentially actionable information. WEDA automation rule sets will use adapted threshold values of a weather parameter to trigger the production of a WEDA advisory. WEDA contains adapted, airport-specific and user-designated weather thresholds for every airport for which it provides advisories. It receives terminal weather forecast information, augmented by observations from local sensors, and uses the forecasts along with the threshold values to identify and generate weather event advisories.
In June, 2016, the MITRE WEDA team visited the Atlanta Air Traffic Control Tower (ATL) and Atlanta approach control facility (A80) to interview traffic managers, supervisors and certified professional controllers (CPCs) to understand how they collectively use weather observations and forecasts to adjust Atlanta’s AAR and ADR values. The WEDA team used this information to define rulesets and threshold values that would be used to provide WEDA advisories for the Atlanta Hartsfield Jackson International Airport (KATL). A WEDA Demonstration Capability (WDC), which resides on a portable tablet computer, was evaluated using tabletop simulation exercises at MITRE/CAASD with a subset of operational ATL and A80 subject matter experts. The results of the tabletop exercises are in the process of being used to inform WDC improvements.
Further WEDA development will focus on its application at additional airports in the NAS. The WDC will be revised based on future laboratory and field exercises. The relationship between WEDA and future releases of the NextGen Weather Processor (NWP), Common Support Services-Weather (CSS-Wx), Aviation weather Display (AWD) and potentially any airport demand DST associated with Terminal Flight Data Management (TFDM) will be explored.