Air traffic control teams are responsible for the safe and efficient control of air traffic through corresponding air sectors. When long term imbalances develop between a team's control capability and the level of control demanded by the sector traffic, inefficiencies develop in the control process. These inefficiencies are seen in sectors where traffic is delayed or rerouted due to overworked control teams, while other sectors have low levels of traffic and underutilized control teams. One technique for resolving these imbalances is to change the area of responsibility for the control team by changing the boundaries of their air sector. However, the determination of the appropriate sector boundary change for improving the situation is a qualitative question for Air Route Traffic Control Center officials. This effort reviews the existing expressions for determining the level of controller workload and presents a decision support model for quantitatively evaluating alternative sector boundary changes. A user specified workload expression is separated into workload components and describes the level of controller workload for each sector in a sectored airspace. The model requires a graphical description of the initial sector arrangement, the values for the controller workload components and a description of the proposed boundary change. The changed sector arrangement is computed from this information and the model provides a description of the resulting air sectors and their associated values for the workload components. The result of the proposed boundary change is seen in the changed sector arrangement and the amount of change is determined by comparing the values of the workload components of the initial and changed sector arrangements. Each sector arrangement is described with a data file and numerical tables. The data file is used for plotting a two-dimensional representation of the sectored airspace. The tables quantify the values of the workload components for each air route in a sector at the sector, air route, and air route section levels. In this manner, the model provides a more objective approach for officials to balance sector workloads. / M.S.

This dissertation aims to reduce urban traffic congestion with street traffic signal control. The traffic signal controllers in the U.S. follow the National Electrical Manufacturing Association Standards (NEMA Standards). In a NEMA controller, the control parameters for a coordinated control are cycle, green splits, and offset. This dissertation proposed a virtual phase-link concept and developed a macroscopic model to describe the dynamics of a traffic network. The coordinated optimal splits control problem was solved using model predictive control. The outputs of the solution are the green splits that can be used in NEMA controllers. I compared the proposed method with a state-of-the-practice signal timing software under coordinated-actuated control settings. It was found that the proposed method significantly outperformed the benchmarking method. I compared the proposed NEMA-based virtual phase-link model and a Max Pressure controller model using Vissim. It was found that the virtual phase-link method outperformed two control strategies and performed close, but not as good as, the Max Pressure control strategy. The disadvantage of the virtual phase-link method stemmed from the waste of green time during a fixed control cycle length and the delay which comes from the slowing down of platoon during a road link to allow vehicles to switch lanes. Compared to the Max Pressure control strategy, the virtual phase-link method can be implemented by any traffic controller that follows the NEMA standards. The real-time requirement of the virtual phase-link method is not as strict as the Max Pressure control strategy. I introduced the offsets optimization into the virtual phase-link method. I modeled the traffic arrival pattern based on the optimization results from the virtual phase-link control method. I then derived a phase delay function based on the traffic arrival pattern. The phase delay function is a function of the offset between two consecutive intersections. This phase delay function was then used for offsets optimization along an arterial. I tested the offsets optimization method against a base case using microscopic simulations. It was found that the proposed offset optimization method can significantly reduce vehicle delays. / Doctor of Philosophy / The goal of this work is to reduce traffic congestion by providing optimized signal timing plans to controllers. Knowing that the controllers in the U.S. follow National Electrical Manufacturing Association (NEMA) Standards, I proposed a virtual phase-link concept and modeled the road traffic network under NEMA controllers’ control as a set of virtual phase-links. Each virtual phase-link corresponds to a NEMA phase at an intersection. I then proposed a NEMA-based virtual phase-link street traffic model. The control variables are the green time allocated to each phase. I compared the proposed NEMA-based virtual phase-link control method with a state-of-the-practice signal timing software using simulation experiments. It was found that the proposed control methods significantly outperformed the signal timing software. I implemented a state-of-the-art adaptive control strategy, Max Pressure control. I compared the proposed NEMA-based virtual phase-link control method with the Max Pressure control strategy. I found that the virtual phase-link control method performed close, but not as good as, the Max Pressure control strategy. The disadvantage of the virtual phase-link method stemmed from the waste of green time during a fixed control cycle length and the delay which comes from the slowing down of platoon during a road link to allow vehicles to switch lanes. The Max Pressure control needs non-conventional controllers which can potentially switch to any phase at any time. Compared to the Max Pressure control strategy, the virtual phase-link method can be implemented by any traffic controller that follows the NEMA standards. The real-time requirement of the virtual phase-link method is not as strict as the Max Pressure control strategy. I then augmented the virtual phase-link method with optimal offsets control. The offsets are the time differences of the coordinated phases comparing to a reference point in a control cycle. I derived a phase delay function and used that function to optimize the offsets by minimizing the associated delays. The simulation experiments showed that the proposed offsets optimization method could reduce the delay along the coordinated path significantly.

The National Aeronautics and Space Administration (NASA) is leading a research effort to develop a Small Aircraft Transportation System (SATS) that will expand air transportation capabilities to hundreds of underutilized airports in the United States. Most of the research effort addresses the technological development of the small aircraft as well as the systems to manage airspace usage and surface activities at airports. The Federal Aviation Administration (FAA) will also play a major role in the successful implementation of SATS, however, the administration is reluctant to embrace the unproven concept. The purpose of the research presented in this dissertation is to determine if the FAA can pursue a resource management strategy that will support the current radar-based Air Traffic Control (ATC) system as well as a Global Positioning Satellite (GPS)-based ATC system required by the SATS. The research centered around the use of the System Dynamics modeling methodology to determine the future behavior of the principle components of the ATC system over time. The research included a model of the ATC system consisting of people, facilities, equipment, airports, aircraft, the FAA budget, and the Airport and Airways Trust Fund. The model generated system performance behavior used to evaluate three scenarios. The first scenario depicted the base case behavior of the system if the FAA continued its current resource management practices. The second scenario depicted the behavior of the system if the FAA emphasized development of GPS-based ATC systems. The third scenario depicted a combined resource management strategy that supplemented radar systems with GPS systems. The findings of the research were that the FAA must pursue a resource management strategy that primarily funds a radar-based ATC system and directs lesser funding toward a GPS-based supplemental ATC system. The most significant contribution of this research was the insight and understanding gained of how several resource management strategies and the presence of SATS aircraft may impact the future US Air Traffic Control system. / Ph. D.

Currently, there is a significant increase in oceanic air traffic. The Federal Aviation Administration (FAA) is attempting to keep pace with this traffic. Automation is being planned in the airline and Air Traffic Control (ATC) system; eventually, all oceanic functions will be part of the FAA Advanced Automation System (AAS). The Oceanic Display and Planning System (ODAPS) capabilities include oceanic flight data processing, conflict probe, flight strip printing; and aircraft situation display capabilities. The Fight Data Input/Output (FDIO) device is currently being used as the main controller input device to the ODAPS. The objective of the Oceanic Air Traffic Control System (OATCS) is to replace the FDIO device with a system that will provide more flexibility and assistance to the oceanic air traffic controller in interfacing with the ODAPS The OA TCS being proposed by this research and thesis is an interim system in support of planned automation. The OATCS will provide the controller with the ability to scroll, and search through previous received ODAPS update, alert, and response messages, and to compose and edit ODAPS flight plan messages. The OATCs will augment and enhance the current functionality of the FDIO system of the ODAPS by providing high technology workstations similar to AAS. The OATCS also will provide the capability to process Automatic Depending Surveillance (ADS) position reports by replacing ODAPS peripherals to improve the working environment for oceanic controllers, the ARINC Communication Center, and the pilot. In addition, the OATCS will support a future two way data link between the oceanic controller and the pilot. / Master of Science

A crescente demanda por transporte aéreo tem provocado um aumento na densidade do fluxo de aeronaves no espaço aéreo. A sobrecarga cada vez maior de aeronaves nos setores estáticos do espaço aéreo, cujos controles são de responsabilidade dos controladores de tráfego aéreo, provoca um estado de alerta constante no gerenciamento do tráfego aéreo. Uma única falha na monitoração e controle dos setores, realizadas pelos controladores de tráfego aéreo, pode por em risco a vida de centenas de pessoas. Para garantir a segurança do espaço aéreo, o controlador de tráfego aéreo tem que realizar várias tarefas no seu dia-a-dia, estando exposto a uma carga de trabalho. Uma das frentes de pesquisas que busca balancear a carga de trabalho dos controladores de tráfego aéreo é a Re-setorização Dinâmica. O objetivo deste trabalho de pesquisa é investigar como se comporta a carga de trabalho dos controladores de tráfego aéreo com a utilização da Re-setorização Dinâmica, tendo como estudo de caso um espaço aéreo brasileiro de alta densidade de aeronaves. / The growing demand for air transportation has caused an increase in the density of aircraft flow in the airspace. The overload of aircraft in airspace sectors, which are under the air traffic controllers\' responsibility, causes a permanent alert state in the air traffic management. A single controller\'s fault with monitoring and controlling a sector may endanger hundreds of people\'s lives. The air traffic controller has to perform many activities daily in order to assure safety to the air space, being exposed to a certain workload. The Dynamic Resectorization is a research line in this direction that aims to balance the workload of the air traffic controllers. The goal of this research work is to investigate the behavior of the air traffic controller workload through the use of Dynamic Resectorization, having as a case study a Brazilian air space with high aircraft density.

A crescente demanda por transporte aéreo tem provocado um aumento na densidade do fluxo de aeronaves no espaço aéreo. A sobrecarga cada vez maior de aeronaves nos setores estáticos do espaço aéreo, cujos controles são de responsabilidade dos controladores de tráfego aéreo, provoca um estado de alerta constante no gerenciamento do tráfego aéreo. Uma única falha na monitoração e controle dos setores, realizadas pelos controladores de tráfego aéreo, pode por em risco a vida de centenas de pessoas. Para garantir a segurança do espaço aéreo, o controlador de tráfego aéreo tem que realizar várias tarefas no seu dia-a-dia, estando exposto a uma carga de trabalho. Uma das frentes de pesquisas que busca balancear a carga de trabalho dos controladores de tráfego aéreo é a Re-setorização Dinâmica. O objetivo deste trabalho de pesquisa é investigar como se comporta a carga de trabalho dos controladores de tráfego aéreo com a utilização da Re-setorização Dinâmica, tendo como estudo de caso um espaço aéreo brasileiro de alta densidade de aeronaves. / The growing demand for air transportation has caused an increase in the density of aircraft flow in the airspace. The overload of aircraft in airspace sectors, which are under the air traffic controllers\' responsibility, causes a permanent alert state in the air traffic management. A single controller\'s fault with monitoring and controlling a sector may endanger hundreds of people\'s lives. The air traffic controller has to perform many activities daily in order to assure safety to the air space, being exposed to a certain workload. The Dynamic Resectorization is a research line in this direction that aims to balance the workload of the air traffic controllers. The goal of this research work is to investigate the behavior of the air traffic controller workload through the use of Dynamic Resectorization, having as a case study a Brazilian air space with high aircraft density.

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

In ongoing efforts to balance air traffic demand and airspace capacity, airspace complexity stands as a fundamental research problem. Taking a more analytic approach, this thesis proposes that airspace complexity can be described in terms of how the airspace (together with the traffic inside it and the traffic control algorithm) responds to disturbances. The response of the airspace to a disturbance is captured by the degree of control activity required to accommodate such disturbance. Furthermore, since the response of the airspace depends on the disturbance, this thesis introduces a complexity map which shows how an airspace responses to a set of different disturbances. Among the many possible types of disturbances, this thesis considers an aircraft entering into the airspace, and the proposed method of describing airspace complexity is illustrated with examples. The time evolution of a complexity map is investigated using a statistical approach. In addition, the proposed method is illustrated in relation to current and future traffic flow management concepts. It is also shown that the proposed method can be applied to airspace design problems.

The study focuses on the Human Factors (HF) discipline and its role in improving aviation safety and efficiency within Air Traffic Control (ATC). The objective is to contribute to a better understanding of the ATC work domain and identify opportunities for improving performance, safety and efficiency. The research also aims to understand air traffic controllers' (ATCs) experience of the Mil i-ATC alarm system and propose enhancements to improve performance. Data collection was executed through observational research at a military air traffic control tower, and semi-structured interviews with ATCs, moreover, Work Domain Analysis and Thematic Analysis were employed for data analysis. The findings highlight key factors influencing ATC operational efficiency and safety, including communication, air traffic management, and alarm management, that is realized through social, technical and physical means. Moreover, workload, stress, situational awareness, teamwork, and decision-making were identified as interrelated elements within ATC. To enhance the Mil i-ATC alarm system, the study recommends considering alarm presentation, taking into account context and operational impact. Moreover, alarms without operational significance and false alarms are identified to cause frustration and undermine the reliability of the alarm system. Further research is necessary to determine the feasibility of presenting action plans directly in the system and how alarms should be listed. It is recommended that future studies focus on sustaining ATCs' motivation and alertness during monotonous tasks or low workload situations. Additionally, it is important to determine the appropriate level of automation in ATC management systems and evaluate controllers' trust in these systems.

Abstract: This thesis addresses the problem of graceful degradation for air traffic management systems (ATMS). The graceful degradation is the process by which the safety of the airspace is ensured in the event of failures or operational degradation in the system. After listing the main areas where failures and degradation can affect the ATMS, an ontology of the ATMS is proposed. The ontology allows to introduce failures at different levels, track their propagation throughout the system, and measure their operational impact. Then, two operational degradations are studied: The first degradation studied is a reduction in the landing capacity at San Francisco International Airport. The aircraft queueing process for terminal area is modeled and optimized to ensure a graceful degradation. The second degradation encompasses Communication, Navigation and Surveillance systems failures. The graceful degradation is ensured by increasing the spacing distance between aircraft, using novel algorithms of avoidance under uncertainties. Those algorithm also serve as probes to compare the degradation capabilities of different traffic configurations such as Miles-In-Trail and Free-Flight arrivals. Finally, this thesis focuses on monitoring the airspace for potential degradation. The ability and the difficulty of en-route traffic configuration are evaluated using degradation maps. Those maps can be used controller to rapidly and efficiently steer traffic from nominal mode of operations to mode of operations under abnormal conditions. Finally, a monitoring tool for terminal area is presented: the conformance of current flight to pre-identified typical operations is determined in real time. As the number of non-conforming aircraft increases, the complexity seen by air traffic controllers increases, and can become a threat for the airspace safety.