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Much like bandwidth in the electromagnetic spectrum, the capacity of the worldwide airspace is a finite resource. Rising demands for air transport incentivize efficient exploitation of this airspace “bandwidth.” As frequent travelers, we know too well the frustrations caused by flight delays that strand us at the gate or leave us circling above an airport. These travel delays are not merely a nuisance. Delays cascade through the air transportation system and cost businesses billions of dollars in lost productivity and fuel. In this era of global warming, excess fuel burn and associated greenhouse gas emissions exact a toll on the environment as well as on the bottom line. Given predicted continuing growth in demand for air cargo and passenger transport, disruptive technologies are urgently needed to reduce air traffic delays and increase capacity. Fortunately, large-scale efforts to reenvision the air transport infrastructure are under way.
This special issue focuses on three significant technologies for restructuring air traffic management: bounded-error navigation, aviation communications networks, and automated algorithms to increase air traffic capacity.
Take a glance at proposed plans for the modernized air transport infrastructure, and you will find that aviation information systems will play a central role in the coming revolution. In the United States, for example, the Federal Aviation Administration (FAA), NASA, Department of Transportation, Department of Defense, and other government agencies are coordinating under the umbrella of the Joint Planning andDevelopment Office (JPDO) to construct the Next Generation Air Transportation System (NextGen). NextGen will exploit novel information system technologies to maximize our use of the airspace. In particular, NextGen seeks to increase air traffic capacity while maintaining extraordinarily high levels of safety. A novel aviation information infrastructure will maintain the workload for human air traffic controllers, without increasing their number, and enhance system flexibility to support the entry of unmanned aircraft systems (UASs) into the national airspace.
Internationally, the aviation research community is just beginning its journey to innovate and coordinate new solutions for air traffic management. This Special Issue on Aviation Information Systems is timely in that it provides an in-depth view of the challenges and opportunities that lie ahead. It is heartening to know that we have talented researchers tackling these challenges, as is demonstrated by the 13 excellent papers that compose this volume.
This Special Issue on Aviation Information Systems zeros in on three of the most significant technologies for restructuring air traffic management: bounded-error navigation, aviation communication networks, and automated algorithms to increase air traffic capacity. We should note that these central themes are by no means an exhaustive list of the information technologies that will be deployed in the next-generation air traffic management system. Topics such as formal validation of flight management software and improved display technologies for maximizing human operator performance will also have an impact. Given the limited space of this volume, however, the papers presented here are intended to paint a tableau of critical ongoing efforts that will revolutionize air traffic management.
The first group of papers presented in this special issue focuses on stunning advances in the field of satellite navigation. The Global Positioning System (GPS) provides 10-m accuracy available worldwide, 24 hours per day, in any weather. This current capability is based on L-band signals broadcast from 30 or more satellites in medium earth orbit. GPS has created such a stir that the Russians are redoubling their efforts to reliably populate the GLONASS orbits. It has motivated the Europeans, Chinese, and Japanese to deploy brand new systems called Galileo, Compass, and the Quasi-Zenith Satellite System, respectively. These new systems also broadcast L-band signals from medium earth orbit. Importantly, the new civil signals provide frequency diversity with three or more civil frequencies per satellite. The accuracy and integrity of satellite navigation will improve based on this frequency diversity from a multiplicity of constellations. The new signals and systems are well described in the paper by Hegarty and Chatre, “Evolution of the Global Navigation Satellite System (GNSS).” The impact on aviation is described by Walter et al. in “Worldwide Vertical Guidance of Aircraft Based on Modernized GPS and New Integrity Augmentations.”
For precision landing, these capabilities can be augmented with a local reference receiver that broadcasts correction data to nearby users of GPS. This capability is called differential GPS or DGPS. The data from the local reference receiver improve accuracy to better than 1 m. More importantly, they also monitor the quality of GNSS signals and provide error bounds in real time. A civil application of DGPS is well describedby Murphy and Imrich in “Implementation and Operational Use of (GBAS) Ground Based Augmentation Systems—A Component of the Future Air Traffic Management System.” A military application is elegantly described by Rife et al. in “Navigation, Interference Suppression, and Fault Monitoring in the Sea-Based Joint Precision Approach and Landing System.”
The second group of papers explores the roles that aviation networks will play in modernizing air traffic management. NextGen and other worldwide efforts seek increased decentralization in air traffic management that will offer greater responsibility and greater flexibility to individual aircraft. An enhanced Traffic Collision and Avoidance System (TCAS), for example, would automatically resolve traffic conflicts at a local level and free controllers to manage entire groups of densely clustered aircraft. This vision requires a new communication infrastructure that robustly and securely passes messages not only between aircraft and controllers but also among distributed aircraft in a local area. To ensure that the costs and benefits of new communications capabilities are equitably shared among stakeholders, Mozdzanowska et al. offer us their paper entitled “Feedback Model of Air Transportation Systems Change: Implementation Challenges for Aviation Information Systems.” This paper employs a controls framework to analyze user acceptance of two key technologies: Automatic Dependent Surveillance-Broadcast (ADS-B), which will distribute GPS coordinates and other information among nearby aircraft; and the UAS infrastructure, which will support operation of automated aircraft in the national airspace.
Constructing aviation communication networks also requires the resolution of several design challenges, including issues of security assurance and effective bandwidth allocation. It is important to recognize that automated capabilities employing externally broadcast data introduce potential vulnerabilities, both to malicious spoofing and to unintentional interference and data errors. Accordingly, new aviation networks must bear the burden of verifying the authenticity and integrity of information received from distributed providers. Sampigethaya et al. explore these pitfalls of wireless networking and possible solutions in their paper entitled “Secure Operation, Control, and Maintenance of Future eEnabled Airplanes.” Aviation networks must also make the most of limited communication bandwidth, especially for safety-critical transmissions on dedicated aeronautical bands. Frew and Brown propose an innovative approach to resolving the multiple access issue by exploiting spatial relationships among aircraft. They describe their approach to meshed aviation communication networks in a paper titled “Airborne Communication Networks for Small Unmanned Aircraft Systems.”
Broadcast of accurate, timely, and secure positioning data will support decentralized conflict resolution for densely packed air traffic. Critical data may not be available at all times, however. Fundamental bandwidth limitations and anomalous system failures must be considered in designing conflict resolution algorithms. Gariel and Feron provide an excellent example in their paper entitled “Graceful Degradation of Air Traffic Operations.” This paper introduces a conflict resolution technique that is robust to communication network failures and to failures of navigation or surveillance subsystems that might result in partial data loss. Even under nominal conditions, it is critical to limit the quantity of data broadcast to enable communication among as many aircraft as possible. With this in mind, Hwang and Seah examine how intentions of other aircraft may be implicitly inferred from their trajectories and used to improve conflict resolution (without requiring the broadcast of explicit intent data). Implementing these and related methods will make the decentralization of air traffic management possible and enable entirely new strategies for managing air traffic flows.
The third and final group of papers delivers several strategies aimed at revolutionizing air traffic management for the high-capacity airspace of the future. In the United States alone, the national airspace is currently managed by hundreds of operators who together handle approximately 50 000 aircraft per day. It is hard to comprehend the complexity of this system, let alone the demands for a new traffic management paradigm. Up to the challenge, Sridhar et al. clearly survey the issues and potential benefits of new traffic management approaches with their paper, “Modeling and Optimization in Traffic Flow Management.”
The most significant bottleneck in augmenting air traffic capacity involves the terminal area airspace which surrounds major airports. Maximizing airport throughput requires extremely efficient and robust methods for scheduling takeoff and landing slots. The paper by Lee and Balakrishnan, “A Study of Tradeoffs in Scheduling Terminal-Area Operations,” explores new methods for improving terminal area throughput and implications for stakeholders, including the airlines and air traffic controllers.
Enhanced terminal area operations will significantly increase the density of air traffic throughout the airspace. Radical new traffic-flow management strategies are thus also needed to handle aircraft en route. In order to promote safe and efficient traffic-flow management without increasing workload, researchers are exploring methods for displaying and controlling groups of flights as aggregate flows rather than as individual aircraft. Work and Bayen propose a creative new approach for managing aggregate traffic flow in “Convex Formulations of Air Traffic Flow Optimization Problems.” To address the interests of multiple stakeholders, Waslander et al. present an exciting alternative mechanism that meters traffic flows based on a competitive bidding process, described in their paper, “Lump-Sum Markets for Air Traffic Control with Competitive Airlines.”
The complex nature of air traffic management, along with a relentless demand for safe and reliable operations, makes system-wide restructuring a daunting prospect. Close coordination of representatives from industry, from the government, and from the research community will be required to implement needed technical advances. We hope the papers in this issue will promote cooperation among these groups by highlighting key challenges and potential solutions for enabling the next generation of air traffic management.▪
The Guest Editors would like to thank the contributors for their diligent research and hard work in preparing their papers. They extend their gratitude to the anonymous reviewers whose commentary has helped ensure consistently high-quality scholarship throughout this issue. We also offer a heartfelt thanks to the staff of the Proceedings of the IEEE and, in particular, to the Managing Editor, J. Calder, and the Publications Editor, J. Sun, without whose assistance this issue would not have been possible.
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