Phil Smith

THE FUTURE NATIONAL AIRSPACE SYSTEM: DESIGN REQUIREMENTS IMPOSED BY WEATHER CONSTRAINTS

In this paper, we present design requirements for the future National Airspace System (NAS) focusing on the most fundamental constraint imposed on this system – namely, the effects of weather. We begin by performing a problem-space analysis in order to classify weather related problems across NAS domains: surface, terminal, and en route. We then identify a set of core ideas that address many of the weather constraints in these domains. The core ideas include flexible traffic management, coupled traffic and weather prediction, and human factors issues that relate to establishing and maintaining common situation awareness between the various decision makers in the NAS. From these core ideas, we discuss a set of functional requirements for the future NAS to enable it to be more robust to the impact of weather and its uncertainty on capacity.

Future Air Traffic Management Requirements for Dynamic Weather Avoidance Routing

We present information requirements for a future air traffic management (ATM) system focusing on dynamic weather avoidance maneuvering. Assuming a net-centric operation (NCO) that provides a mechanism to inform all users of weather forecast information, hazardous weather constraints, and weather avoidance routing requirements, the future ATM system can move away from static jet route routing toward a system where routes are defined dynamically, adjusted during the course of the day as required by traffic demand and the geometry of severe weather constraints. Such an operational concept will be particularly useful for time periods where weather is a major constraint to operating the national airspace system (NAS), and traffic delays or reductions in safety are often the result

Designing On-Demand Coded Departure Routes

Coded Departure Routes (CDRs) help coordinate traffic flows around weather constraints between airports in the National Airspace System (NAS). Today, CDRs are generated far in advance of the day that they are implemented. The routes are maintained in a database and distributed between the Air Traffic Service Provider (ATSP) and the users (airlines). If the weather forecast is highly predictable, the ATSP selects the CDR that best solves a weather avoidance problem, given other traffic flow management constraints. For less predictable weather, the ATSP identifies CDRs that could be used to avoid multiple weather constraint scenarios, asks the NAS users to prepare for this full set of contingencies (alternative CDRs), and then assigns the actual route to the flight as it departs. This paper investigates a method of dynamically generating CDRs based on the latest weather forecast. The benefit of generating CDRs as needed to meet the constraints imposed by the weather forecast is that the routing solution adapts and best fits both the emergent weather pattern and traffic flow requirements. We demonstrate how such weather avoidance routes can be generated with an algorithm that takes into consideration the weather forecast and discuss relevant human factors and domain knowledge requirements.

Requirements for Super Dense Operations for the NGATS Terminal Airspace

We present requirements for super dense operations (SDO) in a future next generation air transportation system (NGATS), targeted at a 2025 timeframe. The requirements emphasize the needs for dynamic weather avoidance maneuvering and performance-based services (PBS) based on required navigation performance (RNP). A net-centric operation (NCO) will provide a mechanism to inform all users of weather forecast information, hazardous weather constraints, and weather avoidance routing requirements. The future air traffic management (ATM) system will move away from static jet route navigation toward a system where routes are defined more dynamically, adjusted during the course of the day as required by traffic demand and the geometry of severe weather constraints. Such a concept of operation (ConOps) will be particularly useful for time periods where weather is a major terminal area constraint in the national airspace system (NAS), making it possible to achieve SDO, reduce traffic delays, and ensure safe operations that would otherwise not be feasible in current day operations.

Designing 4-D trajectories for super-dense operations given weather constraints

For the Next Generation Air Transportation System (NGATS), we present trajectory design guidelines focusing on dynamic weather avoidance routing in transition airspaces -within 200 nmi of an airport or a set of metroplex airports. Assuming a Net-Centric Operation (NCO) that provides a mechanism to inform all users of hazardous weather constraints and weather avoidance routing requirements, the NGATS can move away from static jet route routing toward a system in which routes are defined dynamically in four dimensions (4D), and adjusted during the course of the day as required by traffic demand and the geometry of severe weather constraints. Such an operational concept will be particularly useful for time periods for which weather is a major constraint to terminal area operations, and when Super-Dense Operations (SDO) are thus required to maintain a high throughput. This paper describes both a Concept of Operations (ConOps) for using 4D trajectories to establish SDO in NGATS and an approach to designing 4D trajectories.

Integrated arrival and departure weather avoidance routing within extended terminal airspace

Analysis of historical trajectories showed that when weather is impacting terminal operations, it is common for flights to deviate from published routes, even to the extent of using departure airspace for arrivals. This demonstrates that more flexible routing is needed in terminal airspace, especially when there are weather constraints. In this paper, we present an algorithm for the integrated design of dynamic arrival and departure weather avoidance routing within extended terminal airspace. This algorithm can serve as a strategic planning tool to aid air traffic controllers in managing terminal operations during weather events. Due to safety and efficiency considerations, arrival route structures are first designed and then modeled as constraints when designing the departure routes. The algorithm combines trajectory optimization with heuristics and takes into account human factors constraints, such as distance between merge points and number of merging flows per merge point. We demonstrate through fast-time simulation that dynamic weather avoidance routing can improve terminal operation efficiencies.

Weather avoidance optimal routing for extended terminal airspace in support of Dynamic Airspace Configuration

This paper describes an algorithmic approach for designing dynamic route structures for extended terminal airspace in the presence of convective weather. The algorithm combines trajectory optimization with heuristics to design efficient weather avoidance dynamic route structures. Optimal routing is performed for as far as 150 nautical miles from major airports. In support of Dynamic Airspace Configuration, factors such as distance between merge points, number of merging flows per merge point, and robustness of routes with respect to uncertainties in weather forecasts are explicitly considered. We present analysis of historical terminal operations that was conducted to identify suitable scenarios and also to gain insights and guidance for the design of dynamic route structure. We also present the algorithm details and experimental results.

Future Concepts for Collaborative Traffic Flow Management in the National Airspace System

Because of its cognitive complexity, the responsibility for operating the National Airspace System (NAS) is distributed among many organizations and individuals. An understanding of how this distributed work system functions requires consideration not only of the allocation of control and responsibility, but also of the distribution of data, knowledge, processing capacities and characteristics, goals and priorities. It further requires consideration of how alternative architectures for distributing work (as defined by these different dimensions) impact performance on different types of tasks. Given such a distributed system, one of the most significant challenges is how to plan at a system level, in the face of uncertainty about critical NAS conditions, where the level of uncertainty changes over time. In this paper, a number of concepts for distributing responsibility in the NAS in order to better deal with uncertainty will be discussed, focusing on the need to allocate responsibility so that it better matches access to the knowledge and data necessary to make effective decisions to maintain capacity, safety and equality

A what-if analysis tool for planning airport traffic

This paper presents the implementation and application of a prototype What-if Analysis decision support tool for airport traffic planning. The What-if Analysis tool is used to predict airport traffic performance during a future time horizon with forecast operating conditions and to design Departure Management Programs to mitigate the negative impacts of predicted demand/capacity imbalances. Application scenarios include dynamic weather imposing ground hold and/or Miles-In-Trial restrictions on airport departures. We demonstrate the use of the prototype for a historical traffic and weather scenario at Charlotte Douglas International Airport (CLT). Future work includes enhancing the capabilities and user interfaces of the tool, and researching methods to predict future traffic management initiatives from forecast weather and traffic conditions.