Recent advances in navigation and data communication technologies make it feasible for individual aircraft to plan and fly their trajectories in the presence of other aircraft in the airspace. This way, individual aircraft can take advantage of the atmospheric and traffic conditions to optimally plan their paths. This capability is termed as the free flight concept. While the free flight concept provides new degrees of freedom to the aircraft operators, it also brings-in complexities not present in the current air traffic control system. In the free flight concept, each aircraft has the responsibility for navigating around other aircraft in the airspace. While this is not a difficult task under low speed, low traffic density conditions, the complexities of dealing with potential conflict with multiple aircraft can significantly increase the pilot's work load.

In an effort to increase the efficiency and safety of air travel while accommodating the growing demand for air traffic, the aviation community is working towards designing next generation Air Traffic Management (ATM) systems. ATM will replace the completely centralized, ground based, Air Traffic Control procedures. Within ATM, the concept of Free Flight allows each aircraft to plan four dimensional trajectories in real time, thus replacing the rigid and inefficient discrete airspace structure. These changes are feasible due to GPS and various other technological innovations. In this paper, we propose a decentralized ATM architecture, where much of the current ATC functionality is moved on board each aircraft. Within this framework, we present various issues that arise in the emerging area of hybrid systems based on our work in conflict resolution strategies between aircraft, and in flight mode switching logic. 1 Introduction Air transportation systems are faced with soaring demands ...

Air Traffic Management Systems (ATMS) of the future allow for the possibility of Free Flight, in which aircraft choose their own optimal routes, altitude and speed. In a free flight environment, the trajectories of different aircraft may be conflicting, in which case aircraft may or may not cooperate in resolving the conflict. In this paper, noncooperative conflict resolution methods based on game theory are presented. Each aircraft models the actions of other aircraft as disturbances and tries to defend against the worst possible disturbance. This framework is applied in resolving conflicts between aircraft using speed and heading changes. 1 Introduction Air transportation systems are faced with soaring demands for air travel. According to the Federal Aviation Administration (FAA), the annual air traffic rate in the U.S. is expected to grow by 3 to 5 percent annually for at least the next 15 years. The current National Airspace System (NAS) architecture and management will not...

Air Traffic Management Systems (ATMS) of the future will feature Free Flight, in which aircraft choose their own routes, altitude, and speed, and automated conflict resolution methods in which aircraft will coordinate to resolve conflicts. The resulting distributed control architecture is a hybrid system, with mixed discrete event and continuous time dynamics. SmartATMS is an object oriented modeling and simulation facility which accounts for these hybrid issues and will serve as a uniform modeling framework for the design and evaluation of various ATMS concepts. Keywords: Hybrid Systems, Air Traffic Management Systems, General Applications 1 Introduction Air transportation systems are faced with soaring demands for air travel. The current Air Traffic Management System (ATMS) will not be able to efficiently handle this increase because of inefficient airspace utilization, increased Air Traffic Control (ATC) workload, and obsolete technology. In view of the above problems and in an e...

CTAS environment. BACKGROUND Scott, Dargue, and Goka (1991) examined the effects of adding MLS-equipped aircraft to the traffic flow in a series of simulations contrasting the effects of ILS- versus MLS-equipped aircraft upon airspace operations. The study varied the mixture of ILS- and MLS-equipped aircraft and found that controllers experienced difficulty integrating the two disparate types of traffic. The task of controlling the aircraft proved easier when the composition of MLS aircraft in the overall traffic flow was very low or very high. Overall, however, Scott et al. determined that MLS-equipped aircraft produced reduced flight time from feeder fix to touchdown and increased maximum arrival rates. The controllers participating in the study felt that MLS approaches could improve operations overall. An improvement in operations has also been demonstrated in the development of CTAS. The CTAS software has incorporated the input and active participation of controllers at all stages

The CTAS Descent Advisor (DA), is designed to enable efficient transitions from the en-route to the arrival phase of flight. DA provides the en-route controller with computer generated advisories that conform to flow rate constraints. Test controllers interacted with DA to access and perform an initial evaluation of DA advisories during a field evaluation conducted at the Denver Air Route Traffic Control Center in the Fall of 1995. Test controllers coordinated advisories with sector controllers who issued DA-based clearances during the evaluation. A part-task human factors assessment indicated that sector controllers were able to use DA advisories for efficient and precise descent management. Sector controllers were willing to refer to and evaluate advisories, and where appropriate, provide information about alternative scenarios. Furthermore, sector controllers provided moderately high acceptance ratings for the system concept. They also reported that in the part-task context of the t...

Software systems can be developed through evolution (gradual change) or revolution (reimplementation from scratch). Both approaches have advantages and disadvantages. An evolutionary approach keeps the system working throughout, allowing early problem detection, but tends to retain ingrained design flaws and can result in complex, ad hoc systems. A revolutionary approach is required to change the basic architecture of a system, but many more resources must be invested before the system can be evaluated. In this paper, we describe how we used a little application-specific language to combine these approaches' advantages. The context of our work is CTAS [2], the nextgeneration air traffic control automation system developed originally by NASA. The overall goal was to redesign and reimplement one of the CTAS processes in Java, while retaining its ability to communicatewith unmodified processes---a project complicated by CTAS's ad hoc message formats. To address this, we designed a languag...

It is anticipated that controllers will continue to vector traffic for spacing in the near term where there are Required Navigation Performance (RNP) area navigation (RNAV) routes that merge prior to the final approach or on the final approach. Under moderate to heavy demand, this will negate many of the efficiency, throughput, and predictability benefits of keeping aircraft on the RNP RNAV routes. Given the current level of metering and aircraft equipage, existing decision support automation and avionics capabilities can be used to keep aircraft on the routes and maintain benefits. In an earlier paper, we presented a suite of tools and concepts that address the merging and spacing problems arising from structured RNAV and RNP routes in the terminal environment. This suite of tools and concepts is referred to as Spacing of Performancebased Arrivals on Converging Routes (SPACR). The initial set of tools and concepts addressed the nearterm merging and spacing problem, relying on existing cockpit and ground automation capabilities. In this paper, the tools and concepts are extended to the mid-term, requiring modest modifications of existing capabilities. SPACR includes applications of cockpit capabilities such as FMS Offsets and Required Time of Arrival (RTA) and ground automation functionalities such as the embedded ghosting function in the Automated Radar Terminal

this report are available for $5.00 each from the Department of Cognitive Science, UCSD, La Jolla, CA 92093-0515. A PostScript version of this report is available by anonymous ftp from cogsci.ucsd.edu in /pub/tr. Copyright 1994 by Christine A. Halverson. Distributed Cognition as a Theoretical Framework for HCI: Don't Throw the Baby out with the Bathwater --the Importance of the Cursor in Air Traffic Control 1 Christine A. Halverson Department of Cognitive Science, 0515 University of California, San Diego 9500 Gilman Drive La Jolla CA, 92093-0515 USA email: halverso@cogsci.ucsd.edu PH: 619-534-4348 FAX: 619-534-1128 Introduction Two of the roles of theory in human computer interaction (HCI) are to aid design and analysis. However, theories can often be unwieldy in their application. Thus the demonstration of a particular theory in application to a problem in HCI may be the best demonstration of that theory's utility. In this paper, I present the theory of distributed cognition and apply it to the analysis of an automation tool for air traffic control (ATC). This example demonstrates how: 1) the theory of distributed cognition influences and informs every step of the process of analysis and redesign; 2) any interaction is embedded in a domain and thus a socio-cultural context that must be considered; and 3) that understanding what to retain of an existing design is as important as the evaluation of enhancements. 1 Originally presented as a position paper for the InterCHI '93 Workshop -- Rethinking Theoretic Frameworks for Human-Computer Interaction. Yvonne Rogers, Liam Bannon, and Grahm Button, Chairs. Research support was provided by cooperative agreement NCC2-591 to Edwin Hutchins from the Ames Research Center of the National Aeronautics and Space Administration (NASA...

The development of advanced automation for arrival aircraft into the terminal area is being investigated for both the air traffic control (ATC) and airborne environments. For the automation to be effective and provide the best advisory information, aircraft trajectories must be accurately estimated. One way to enhance the aircraft's adherence to the trajectories assumed by advanced ATC automation is to supply trajectory information to the pilots. Such information is currently provided by ATC to pilots through voice communication. Providing the advisories to the pilots via their Flight Management Systems (FMS) could help improve the timeliness of the advisories, especially in a time-critical terminal area environment. To successfully implement the FMS for use in the terminal area, human factors issues such as pilot workload and the usability and understandability of the information presented via the FMS must be addressed. This study examines the human factors aspects of FMS usage strate...