Sanjiv Shresta

Modeling of air traffic arrival operations through agent-based simulation

This paper reports on the development and validation of an agent based simulation model of air traffic control arrival operations. The simulation model includes modeling of both the structure and procedures of air traffic operations. It is thus suitable for evaluating the impacts of shifts in those structures and procedures. Three key operational metrics are introduced which are sensitive to the internal workings of air traffic arrival operations. The simulation model is validated by demonstrating agreement in those key metrics between the simulation and a set of baseline arrival operations radar data. After the simulation model has been shown to reproduce actual operations, select details of the simulation can be altered to incorporate proposed operational changes. The impact of the changes on the computer simulation will offer a prediction of how the operational changes will affect actual operations.

Benefits and constraints of time-based metering along RNAV STAR routes

The NextGen Integration and Implementation Office of the Federal Aviation Administration has outlined a set of novel operational concepts for improving the efficiency of air traffic operations. In the terminal domain, one proposed operational change is Time-Based Metering (TBM) utilizing Area Navigation (RNAV) Standard Terminal Arrival (STAR) route assignments. The MITRE Corporations Center for Advanced Aviation System Development (CAASD) was tasked to provide benefits and feasibility analysis of these proposed changes and to develop models to test concepts for use in the management and control of air traffic. This paper describes the evaluation of potential benefits and constraints on the feasibility of implementing TBM along RNAV STAR routes. It focuses on computer simulated trial runs of a case study in which time-based metered delivery is implemented at Hartsfield-Jackson Atlanta International airport. This study has yielded two important findings. The first finding is the maximum tolerable variation of actually realized en-route to terminal delivery times from the prescribed schedule times. The second finding is an estimate of the potential reduction in low altitude vectoring in high density airspace.

Analysis of observed aircraft-to-aircraft separations

As air traffic demand continues to increase in the coming years, the need for concepts, procedures and tools that can improve airspace efficiency will likewise increase. Reduction of terminal and en-route separation minima has been the focus of many of the concepts and emerging technologies developed to respond to this need. Horizontal separation distances consist of two major elements: lateral separation (i.e. track-to- track) influenced by the spacing of parallel or converging routes and individual aircraft route conformance; and longitudinal separation (i.e. along-track) influenced by both Federal Aviation Administration (FAA) Orders regarding standard separations minima and an additional spacing buffer which reflects controller comfort with position variability and work load. This paper presents the preliminary results of an investigation of current terminal and en-route separations observed on conventional and Area Navigation (RNAV) routes and procedures. This analysis has been undertaken to determine the magnitude of spacing buffers as they are applied today, and then model a future throughput capability that could result from reducing the currently applied separations toward the established minimums.

Time-based flow management (TBFM) transient disruption analysis

• Planned study will: - Simulate arrival operations into DTW with TBM and MIT delivery - Compare strategies for responding to a transient disruption which reduces the AAR - Offer guidance on: • Procedural changes for continuing TBM during a transient disruption • Automation enhancements required for continuing TBM during a transient disruption • The benefits attainable from continuing TBM during a transient disruption

Probabilistic Modeling and Assessment Tool Design and Evaluation

This paper describes the development and evaluation of a prototype decision support tool (DST) called the Probabilistic Modeling and Assessment Tool (PMAT). The DST is designed to help traffic management coordinators adjust the parameter settings of Traffic Management Advisor (TMA) in response to forecast changes in airport acceptance rate (AAR). Using an internal fast-time simulation of arrival operations, PMAT generates estimates of the delays arriving aircraft will experience based on the incoming demand and probabilistic AAR forecast. PMAT may accept forecast AAR from weather or non-weather based plans for managing airport capacity. When the probabilistic AAR forecast is due to weather, PMAT will provide the air traffic management DST portion of the ATM-Weather Integration Plan. The use of a DST for proactively responding to an AAR forecast has several novel elements including a forecast probability matrix, operational impact metrics, and presentation of metrics for multiple alternatives. These elements were evaluated in a set of Human-in-the-Loop (HITL) simulations employing traffic management coordinators at Los Angeles and Atlanta Air Route Traffic Control Centers (ZLA and ZTL, respectively) and Southern California and Charlotte Terminal Radar Approach Controls (SCT and CLT, respectively). Among the participants, 95 percent said that they would use PMAT to help them make decisions every day or whenever there was a potential weather disruption. Benefits that the HITL participants saw from a tool like PMAT included greater confidence to deliver high demand under marginal conditions when the potential airborne holding is reasonable for their facility, and improved coordination with other NAS stakeholders.