Determining FAA Mid-Term Aviation Weather Requirements for Traffic Flow Management - the Transition to NextGen

As the Federal Aviation Administration (FAA) transitions to the Next Generation Air Transportation System (NextGen), the mid-term National Airspace System (NAS) must be fully defined through sets of operational, functional and performance requirements. For the weather community, this begins with the determination of the weather information needs of NAS decision-makers based on their mid-term operational requirements. To determine aviation weather needs for the mid-term (2018), there are several challenges to address. These are:

• Identifying the weather information needs to support operational decision-making

• Having decision-makers validate the needed accuracy for weather information

• Verifying the format needed to integrate weather information into Decision Support Tools (DSTs)

• Identifying user DSTs capable of weather integration in the mid-term

The first and most important challenge is to determine “what weather information is needed” in the mid-term. Why is that? Knowing “what weather information is needed” is a key factor in developing the transition from the current NAS to NextGen via the implementation of the NAS enterprise architecture. Without a complete knowledge of the needed mid-term weather information needs, the FAA can't develop a weather roadmap that ensures the successful transition to the mid-term and then to NextGen.

However, identifying the required weather information alone is not enough. In order for the weather information to assist the operational decision-maker in improving their decisions, the ‘goodness' of the weather information must also be determined. How good the information must be is determined by the decision-makers and is usually evaluated in terms of its accuracy. This includes how precise the observation is measured or how well the forecast matched the observation, as well the latency, the spatial and temporal resolutions, and the magnitude accuracies of the various weather elements. Once the decision-makers have validated the required accuracy values, the associated performance requirements are developed. These performance requirements drive the selection of solutions developed as part of the FAA's Acquisition Management System for the various capabilities of the NAS weather architecture, i.e., observing, forecasting, and dissemination.

The operational need for NextGen is driven by present-day shortfalls in the areas of capacity, flexibility, efficiency, safety, security, environment, and situational awareness. Weather is a major contributor to today's capacity problems, largely due to the lack of prediction accuracy and timeliness and the broad-brush approaches used to manage traffic impacted by weather. The need to fine-tune weather impacts to specific flights and provide better routing/re-routing options around weather is essential to accommodate future traffic growth. The sooner the FAA can identify user needs, develop requirements and implement new weather capabilities, the earlier some NextGen benefits are accrued by NAS users. Therefore, determining “what weather information is needed,” as well as the accompanying performance requirements early in the mid-term is crucial to preclude missing requirements surfacing later in the acquisition cycle, which is costly. This is especially true when they emerge during final system testing and results in unanticipated delays plus cost and schedule overruns.

To begin this process, representatives from the FAA and NWS are working with Traffic Flow Management (TFM) specialists to determine their 2018 weather information needs. A joint FAA and NWS TFM Weather Requirements Working Group (TRWG) formed in August 2010. The group objectives are to:

• Baseline current NWS weather forecast support capability

• Develop requirements for weather information services for NextGen Mid-term Operational Capability (MOC)

• Establish a plan to implement solutions meeting those requirements

The TRWG Requirements sub-team evaluated the Mission Need Statement for Aviation Weather (MNS # 339) to determine the weather information associated with TFM decisions (i.e., airport acceptance rate determination, ground stop/delay decision, route changes, Severe Weather Avoidance Plan (SWAP) Implementation, metering/spacing decisions, and airspace flow program decisions). The team developed functions and functional requirements for the TFM-needed weather information. They also developed surveys to help refine the initial TFM weather needs list. The TRWG TFM specialists reviewed the resulting set of functional requirements and selected the final list of needed weather information. Then the team developed the complete set of MOC TFM weather performance requirements and submitted them to the TRWG and other representatives of the TFM organization for review and comment. This methodology will be repeated with other NAS decision-makers to develop a complete set of weather performance requirements for the mid-term.

To establish a weather performance baseline for TFM, the NWS is identifying the current weather forecast performance capabilities. When NWS has completed their baselined weather performance requirements, the FAA will perform a gap analysis to determine how much improvement in observing and forecasting weather is required to meet the TFM mid-term aviation weather needs. A transition plan will be developed to determine how to mitigate the gaps in weather services to meet mid-term operational needs.

The rigorous requirements effort performed by the TRWG Requirements sub-team to establish TFM weather performance requirements for the mid-term is important for two reasons. First, it ‘jump starts' the process of determining ‘what weather information is needed' in the mid-term. Secondly, it facilitates the selection of the best solutions for observing, forecasting, and disseminating aviation weather information. The FAA will use the user-validated performance requirements to mitigate the current gaps in NAS weather information. These performance requirements will then be allocated to FAA systems and NWS services to implement improved observation accuracy (spatial and temporal resolution) and increased forecast accuracy skill, latency, and reliability).

Although the first set of validated performance requirements have been developed for TFM, the same process will be used to develop weather performance requirements for all NAS decision-makers. Such requirements would be independent of the weather information source (e.g., within the FAA weather enterprise architecture, NWS, etc.). The early development of all mid-term weather performance requirements becomes even more crucial given the austere funding environment faced by both the FAA and NWS as delays could result in capabilities being reduced or even cancelled.