Human-centered automation of air traffic control operations in the terminal area

Cover titleNovember 2, 1994Series statement handwritten on coverProposal for the Interdepartmental Doctoral Program in Human Factors and AutomationIncludes bibliographical references (p. 70-73)Introduction: Air Traffic Control operations are described extensively in the ATC manuals such as the Airman's Information Manual [1] and the ATC Controller's Handbook [2]. Mathematical analysis has also been conducted for the ATC operations as evident in the many theses that have been published in ATC research [3, 4, 5]. A brief description is due here however in order to provide a background for the following document. There are six major ATC functions in the terminal area and a summary of their description in Sadoune's thesis [5] follows: Flow Management: The flow management purpose is to provide efficient transition between the en-route corridors and the terminal area through the metering fixes. The en-route corridors are the airways connecting the airports, the terminal area is the designated space around the airport, and the metering fixes are the points at which aircraft enter the terminal area under the flow control process called metering. The flow management system is capable of delivering the aircraft to the metering fix at predetermined time, altitude, and speed, minimizing fuel consumption and flight time. Beyond the metering fix however the concern in no longer fuel and cost, it is the separation between the aircraft and the landing schedule. Ground-based flight path generation is needed at that point. Runway Scheduling: The runway capacity is the limiting factor of the flow of traffic at congested airports. There are many reasons why runways are not used efficiently in the current tactical practice. These include the independent scheduling of landings and takeoffs, the ad hoc fashion in which takeoffs are inserted between landings, and the common use of the first-come-first-serve approach which is fair but not optimal. Runway scheduling is a queuing process and can be optimized for maximum throughput, long term service, and minimum delays of aircraft, taking into account fuel consumption, duration of flight, and other factors. The difficulty is in the dynamic nature of the schedule where modifications are needed as new entrants arrive or as environmental conditions change. The determination of the runway capacity and its improvement through the use of advanced technologies are discussed in Flow Control: Through traffic redistribution the flow control process helps smooth the demand fluctuations leading to a controlled number of aircraft simultaneously present in the terminal area. Two processes accomplish flow control: metering and holding. Metering divides the approach to the airport into successive stages between metering fixes. The flow management system delivers the aircraft to the metering fixes at the predetermined time, altitude, and speed. Holding points are assigned where holding aircraft are stacked and isolated from traffic. Holding aircraft circle in holding patterns awaiting landing clearance. Therefore, while metering moves the delays resulting from the runway capacity upstream, holding extends the flight path in time to accommodate arrival delays. These practices however can result in idle runway time in favor of more flow control leading to less efficient use of the runway. Flight Path Generation: There are standard routes both from the terminal area entry points to the runway for approach and from the runway to the en-route corridors for departure. These predefined routes can be used at low traffic flow rates, and add to the precision since automatic flight control systems are capable of flying along them automatically. However they are not optimal in using the space, or in exploiting the aircraft capabilities, or in maximizing the runway capacity. Automated flight path generation allows the incorporation of the space organization, the ATC separation criteria, the landing and takeoff schedule, the aircraft dynamics and performance limitations, and the maneuvering characteristics of the pilot in generating more optimal and flexible paths. This subject will be emphasized further in this document. Path Conformance Monitoring: In order to supervise the execution of the flight path plan, the radar surveillance system provides vague and non-precise measurement of the position of the aircraft. The controllers base their estimates of the conformance on 2-dimensional radar displays, and have to wait few intervals to estimate the direction of the aircraft. To adjust for the path conformance error the controllers issue heading, altitude, and speed clearances (vectors) to the pilots. Communication between controllers and pilots is done via radio transmission. Errors result from misunderstanding between the pilot and the controller, pilot response, as well as wind and unexpected atmospheric disturbances. Again new technologies and more automation are expected to improve the path conformance capabilities. These include better surveillance using satellites, digital data links for communication between the controller and the pilot, and display of the path to the pilot on board the aircraft. Questions of resolution and threshold of the conformance error become critical to the automation of the monitoring function. Hazard Monitoring: This includes detecting possible collisions between aircraft and with the ground. There is a trade off between false alarms and missed alarms in setting the threshold for the hazard alarm. Namely the more conservative the alarm threshold is set, the less is the risk of collision due to a missed alarm. But the disturbance to the traffic flow caused by the large number of false alarms is higher

Semi-Structured Decision Processes: A Conceptual Framework for Understanding Human-Automation Decision Systems

The purpose of this work is to improve understanding of existing and proposed decision systems, ideally to improve the design of future systems. A "decision system" is defined as a collection of information-processing components -- often involving humans and automation (e.g., computers) -- that interact towards a common set of objectives. Since a key issue in the design of decision systems is the division of work between humans and machines (a task known as "function allocation"), this report is primarily intended to help designers incorporate automation more appropriately within these systems. This report does not provide a design methodology, but introduces a way to qualitatively analyze potential designs early in the system design process. A novel analytical framework is presented, based on the concept of "semi-Structured" decision processes. It is believed that many decisions involve both well-defined "Structured" parts (e.g., formal procedures, traditional algorithms) and ill-defined "Unstructured" parts (e.g., intuition, judgement, neural networks) that interact in a known manner. While Structured processes are often desired because they fully prescribe how a future decision (during "operation") will be made, they are limited by what is explicitly understood prior to operation. A system designer who incorporates Unstructured processes into a decision system understands which parts are not understood sufficiently, and relinquishes control by deferring decision-making from design to operation. Among other things, this design choice tends to add flexibility and robustness. The value of the semi-Structured framework is that it forces people to consider system design concepts as operational decision processes in which both well-defined and ill-defined components are made explicit. This may provide more insight into decision systems, and improve understanding of the implications of design choices. The first part of this report defines the semi-Structured process and introduces a diagrammatic notation for decision process models. In the second part, the semi-Structured framework is used to understand and explain highly evolved decision system designs (these are assumed to be representative of "good" designs) whose components include feedback controllers, alerts, decision aids, and displays. Lastly, the semi-Structured framework is applied to a decision system design for a mobile robot.Charles Stark Draper Laboratory, Inc., under IR&D effort 101

Uma abordagem para a modelagem, analise e controle de sistemas de produção utilizando Redes de Petri

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro TecnologicoAs redes de Petri estão sendo atualmente utilizadas em sistemas de manufatura. Neste sentido, o presente trabalho tem como propósito apresentar os diferentes conceitos relativos às redes de Petri e suas várias classes de modelos derivados, os quais podem ser utilizados para modelar sistemas dinâmicos de eventos discretos de qualquer tipo. Esta ferramenta nos permite visualizar com facilidade situações tais como concorrência, sincronização e compartilhamento de recursos, os quais são próprios de um sistema flexível de manufatura (FMS), além do mais, nos permite uma análise tanto qualitativa como quantitativa. Cada um dos modelos derivados tais como RdP estocásticas, RdP colorida, etc. Têm seu próprio caráter específico e campo de aplicação privilegiado

Semi-structured decision processes : a conceptual framework for understanding human-automation systems

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999.Includes bibliographical references (p. 191-199).The purpose of this work is to improve understanding of existing and proposed decision systems, ideally to improve the design of future systems. A "decision system" is defined as a collection of information-processing components-often involving humans and automation (e.g., computers)-that interact towards a common set of objectives. Since a key issue in the design of decision systems is the division of work between humans and machines (a task known as "function allocation"), this thesis is primarily intended to help designers incorporate automation more appropriately within these systems. This thesis does not provide a design methodology, but introduces a way to qualitatively analyze potential designs early in the system design process. A novel analytical framework is presented, based on the concept of "semi-Structured" decision processes. It is believed that many decisions involve both well-defined "Structured" parts (e.g., formal procedures, traditional algorithms) and ill-defined "Unstructured" parts (e.g., intuition, judgment, neural networks) that interact in a known manner. While Structured processes are often desired because they fully prescribe how a future decision (during "operation") will be made, they are limited by what is explicitly understood prior to operation. A system designer who incorporates Unstructured processes into a decision system understands which parts are not understood sufficiently, and relinquishes control by deferring decision-making from design to operation. Among other things, this design choice tends to add flexibility and robustness. The value of the semi-Structured framework is that it forces people to consider system design concepts as operational decision processes in which both well-defined and ill-defined components are made explicit. This may provide more insight into decision systems, and improve understanding of the implications of design choices. The first part of this thesis defines the semi-Structured process and introduces a diagrammatic notation for decision process models. In the second part, the semi-Structured framework is used to understand and explain highly evolved decision system designs (these are assumed to be representative of "good" designs) whose components include feedback controllers, alerts, decision aids, and displays. Lastly, the semi-Structured framework is applied to a decision system design for a mobile robot.by William N. Kaliardos.Ph.D