Human performance interfaces in air traffic control

This paper examines how human performance factors in air traffic control (ATC) affect each other through their mutual interactions. The paper extends the conceptual SHEL model of ergonomics to describe the ATC system as human performance interfaces in which the air traffic controllers interact with other human performance factors including other controllers, software, hardware, environment, and organisation. New research hypotheses about the relationships between human performance interfaces of the system are developed and tested on data collected from air traffic controllers, using structural equation modelling. The research result suggests that organisation influences play a more significant role than individual differences or peer influences on how the controllers interact with the software, hardware, and environment of the ATC system. There are mutual influences between the controller-software, controller-hardware, controller-environment, and controller-organisation interfaces of the ATC system, with the exception of the controller-controller interface. Research findings of this study provide practical insights in managing human performance interfaces of the ATC system in the face of internal or external change, particularly in understanding its possible consequences in relation to the interactions between human performance factors.     

Adapting exercise selection to performance,effort and self-esteem

ABSTRACT

Adapting to learner characteristics is essential when selecting exercises for learners in an intelligent tutoring system. This paper investigates how humans adapt next exercise selection (in particular difficulty level) to learner personality, invested mental effort, and performance to inspire an adaptive exercise selection algorithm. First, the paper describes the investigations to produce validated materials for the main studies, namely the creation and validation of self-esteem personality stories, mental effort statements, and mathematical exercises with varying levels of difficulty. Next, through empirical studies, we investigate the impact on exercise selection of learner's self-esteem (low versus high self-esteem) and effort (minimal, little, moderate, much, and all possible effort). Three studies investigate this for learners who had different performances on a previous exercise: just passing, just failing, and performed well. Participants considered a fictional learner with a certain performance, self-esteem and effort, and selected the difficulty level of the next mathematical exercise. We found that self-esteem, mental effort, and performance all impacted the difficulty level of the exercises selected for learners. Finally, using the results from the studies, we propose an algorithm that selects exercises with varying difficulty levels adapted to learner characteristics.     

Modeling and predicting mental workload in en route air traffic control: critical review and broader implications

OBJECTIVE: We perform a critical review of research on mental workload in en route air traffic control (ATC). We present a model of operator strategic behavior and workload management through which workload can be predicted within ATC and other complex work systems. BACKGROUND: Air traffic volume is increasing worldwide. If air traffic management organizations are to meet future demand safely, better models of controller workload are needed. METHOD: We present the theoretical model and then review investigations of how effectively traffic factors, airspace factors, and operational constraints predict controller workload. RESULTS: Although task demand has a strong relationship with workload, evidence suggests that the relationship depends on the capacity of the controllers to select priorities, manage their cognitive resources, and regulate their own performance. We review research on strategies employed by controllers to minimize the control activity and information-processing requirements of control tasks. CONCLUSION: Controller workload will not be effectively modeled until controllers' strategies for regulating the cognitive impact of task demand have been modeled. APPLICATION: Actual and potential applications of our conclusions include a reorientation of workload modeling in complex work systems to capture the dynamic and adaptive nature of the operator's work. Models based around workload regulation may be more useful in helping management organizations adapt to future control regimens in complex work systems.     

Fuzzy signal detection theory: analysis of human and machine performance in air traffic control,and analytic considerations

This paper applies fuzzy SDT (signal detection theory) techniques, which combine fuzzy logic and conventional SDT, to empirical data. Two studies involving detection of aircraft conflicts in air traffic control (ATC) were analysed using both conventional and fuzzy SDT. Study 1 used data from a preliminary field evaluation of an automated conflict probe system, the User Request Evaluation Tool (URET). The second study used data from a laboratory controller-in-the-loop simulation of Free Flight conditions. Instead of assigning each potential conflict event as a signal (conflict) or non-signal, each event was defined as a signal (conflict) to some fuzzy degree between 0 and 1 by mapping distance into the range [0, 1]. Each event was also given a fuzzy membership, [0, 1], in the set ‘response’, based on the perceived probability of a conflict or on the colour-coded alert severity. Fuzzy SDT generally reduced the computed false alarm rate for both the human and machine conflict systems, partly because conflicts just outside the conflict criterion used in conventional SDT, were defined by fuzzy SDT as a signal worthy of some attention. The results illustrate the potential of fuzzy SDT to provide, especially in exploratory data analysis, a more complete picture of performance in aircraft conflict detection and many other applications. Alternative analytic methods also using fuzzy SDT concepts are discussed.     

Fuzzy signal detection theory: analysis of human and machine performance in air traffic control,and analytic considerations

This paper applies fuzzy SDT (signal detection theory) techniques, which combine fuzzy logic and conventional SDT, to empirical data. Two studies involving detection of aircraft conflicts in air traffic control (ATC) were analysed using both conventional and fuzzy SDT. Study 1 used data from a preliminary field evaluation of an automated conflict probe system, the User Request Evaluation Tool (URET). The second study used data from a laboratory controller-in-the-loop simulation of Free Flight conditions. Instead of assigning each potential conflict event as a signal (conflict) or non-signal, each event was defined as a signal (conflict) to some fuzzy degree between 0 and 1 by mapping distance into the range [0, 1]. Each event was also given a fuzzy membership, [0, 1], in the set 'response', based on the perceived probability of a conflict or on the colour-coded alert severity. Fuzzy SDT generally reduced the computed false alarm rate for both the human and machine conflict systems, partly because conflicts just outside the conflict criterion used in conventional SDT, were defined by fuzzy SDT as a signal worthy of some attention. The results illustrate the potential of fuzzy SDT to provide, especially in exploratory data analysis, a more complete picture of performance in aircraft conflict detection and many other applications. Alternative analytic methods also using fuzzy SDT concepts are discussed.     

Understanding and overcoming horizontal separation complexity in air traffic control: an expert/novice comparison

Cognition, Technology & Work - Humans still play a key role in air traffic control but their performances limit the capacity of the airspace and are responsible for delays. At the tactical...     

Automation in future air traffic management: effects of decision aid reliability on controller performance and mental workload

Future air traffic management concepts envisage shared decision-making responsibilities between controllers and pilots, necessitating that controllers be supported by automated decision aids. Even as automation tools are being introduced, however, their impact on the air traffic controller is not well understood. The present experiments examined the effects of an aircraft-to-aircraft conflict decision aid on performance and mental workload of experienced, full-performance level controllers in a simulated Free Flight environment. Performance was examined with both reliable (Experiment 1) and inaccurate automation (Experiment 2). The aid improved controller performance and reduced mental workload when it functioned reliably. However, detection of a particular conflict was better under manual conditions than under automated conditions when the automation was imperfect. Potential or actual applications of the results include the design of automation and procedures for future air traffic control systems.     

航管仿真训练系统运行控制的设计与实现

描述了对航管仿真系统运行控制机制的设计和实现。先对系统功能做了简要介绍,再从进程组的监控、基于多个队列的进程调度设计等方面介绍了系统的实现过程和处理细节,最后采用负载均衡算法针对系统进行了优化设计。本系统最终实现了对进程实施定位和运行监视,对控制指令采用命令优先级处理机制,使用多个队列调度进程,从而完成训练计划,较好地控制了航管仿真训练系统的运行。     

High versus low contextual interference in simulation-based training of troubleshooting skills: effects on transfer performance and invested mental effort

The effects of contextual interference on practice behavior, transfer performance, and cognitive load for learning troubleshooting skills were studied. A low contextual interference (LCI) condition, in which subjects practiced to diagnose system failures in a blocked schedule, was compared with a high contextual interference (HCI) condition, in which failures were practiced in a random schedule. The following hypotheses are stated. Hypothesis 1: during practice, subjects in the HCI group will require more time to reach a high performance level (i.e., more accurate and/or faster diagnoses of system failures) on practice problems and will have to invest more mental effort relative to subjects in the LCI group. Hypothesis 2: subjects in the HCI group will show higher performance and lower invested mental effort on far transfer test problems, relative to subjects in the LCI group, but there will be no difference between the groups on near transfer test problems. The results showed that subjects in the HCI group were more accurate in diagnosing far transfer problems, although during practice they needed more time to diagnose system failures and made significantly more incorrect diagnoses.     

Power law model for subjective mental workload and validation through air traffic control human-in-the-loop simulation

Cognition, Technology & Work - We provide evidence for a power law relationship between the subjective one-dimensional Instantaneous Self Assessment workload measure (five-level ISA-WL scale)...     

Dynamics and control technologies in air traffic management

Dynamics and Control technologies play a central role in the development and operation of decision support systems of modern air traffic management systems. Recent emergence of Global Navigation Satellite Systems and satellite-based augmentation systems have enabled higher precision execution of aircraft trajectories, opening-up the potential for the implementing more quantitative air traffic management approaches. Already, this navigation capability is enabling higher traffic through puts, and safer operation of aircraft in the proximity of the terrain at several major airports in the US. This paper discusses the aircraft trajectory optimization, conflict resolution algorithms, and traffic flow management problems which form the essential components of the evolving air traffic management system. It will be shown that Optimal Control Theory, Model Predictive Control and the Discrete Event Systems theory form the underlying analytical machinery in this domain. Finally, the paper will outline some of the algorithms for realizing the Trajectory Based Operations concept, currently being developed for future air traffic management.     

Redesigning air traffic control: an exercise in software design

This case study demonstrates how basic software engineering techniques can make a complex system dramatically simpler. The authors describe lessons learned from reverse engineering an air traffic control system with a variety of tools and redesigning it to be smaller, simpler and more flexible     

Attentional costs and failures in air traffic control notifications

Large display screens are common in supervisory tasks, meaning that alerts are often perceived in peripheral vision. Five air traffic control notification designs were evaluated in their ability to capture attention during an ongoing supervisory task, as well as their impact on the primary task. A range of performance measures, eye-tracking and subjective reports showed that colour, even animated, was less effective than movement, and notifications sometimes went unnoticed. Designs that drew attention to the notified aircraft by a pulsating box, concentric circles or the opacity of the background resulted in faster perception and no missed notifications. However, the latter two designs were intrusive and impaired primary task performance, while the simpler animated box captured attention without an overhead cognitive cost. These results highlight the need for a holistic approach to evaluation, achieving a balance between the benefits for one aspect of performance against the potential costs for another.

Practitioner summary: We performed a holistic examination of air traffic control notification designs regarding their ability to capture attention during an ongoing supervisory task. The combination of performance, eye-tracking and subjective measurements demonstrated that the best design achieved a balance between attentional power and the overhead cognitive cost to primary task performance.     

Determinants of conflict detection: a model of risk judgments in air traffic control

OBJECTIVE: A model of conflict judgments in air traffic control (ATC) is proposed. BACKGROUND: Three horizontal distances determine risk judgments about conflict between two aircraft: (a) Dt(o) is the distance between the crossing of the aircraft trajectories and the first aircraft to reach that point; (b) Dt(h) is the distance between the two aircraft when they are horizontally closest; and (c) Dt(v) is the horizontal distance between the two aircraft when their growing vertical distance reaches 1000 feet. METHODS: Two experiments tested whether the variables in the model reflect what controllers do. In Experiment 1, 125 certified controllers provided risk judgments about situations in which the model variables were manipulated. Experiment 2 investigated the relationship between the model and expertise by comparing a population of certified controllers with a population of ATC students. RESULTS: Across both experiments, the model accounted for 44% to 50% of the variance in risk judgments by certified controllers (N=161) but only 20% in judgments by ATC students (N=88). There were major individual differences in the predictive power of the model as well as in the contributions of the three variables. In Experiment 2, the model described experts better than novices. CONCLUSION: The model provided a satisfying account of the data, albeit with substantial individual differences. It is argued that an individual-differences approach is required when investigating the strategies involved in conflict judgment in ATC. APPLICATION: These findings should have implications for developing user-friendly interfaces with conflict detection devices and for devising ATC training programs.     

Simulation techniques in operator and maintenance training,performance assessment,and personnel selection

Recent military research has examined the use of synthetic simulators employing new digital technologies for training personnel who operate and maintain electronic and other systems. Compared with the traditional approach using actual equipment for training, such simulators are safer for trainees and equipment, more reliable, more flexible, and far less costly. These synthetic trainers can be self-pace and combine two-dimensional presentation for teaching conceptual skills with full-scale 3-dimensional simulation for teaching hands-on skills. The synthetic training approach is directly applicable to the industrial marketplace, and can offer improvements in personnel selection and performance assessment as well as better training.     

The role of the air traffic controller in future air traffic management: an empirical study of active control versus passive monitoring

Proposals for air traffic management such as Free Flight call for a transfer of responsibility for separation between aircraft from air traffic controllers (ATCos) to pilots. Under many proposals, the role of the ATCo will change from one of active control to passive monitoring. The present study directly compared these types of control with respect to ATCo mental workload, conflict detection, and memory. Eighteen ATCos participated in an air traffic control simulation of Free Flight procedures under moderate and high traffic load. Dependent variables included accuracy and timeliness in detecting potential conflicts, accepting and handing off aircraft, mental workload (as assessed by a secondary task, heart rate variability, and subjective ratings), and memory for aircraft location. High traffic density and passive control both degraded conflict detection performance. Actual or potential applications of this research include the recommendation that designs for future air traffic management keep authority for separation of aircraft with the controller.     

Development and application of a human error identification tool for air traffic control

This paper outlines a human error identification (HEI) technique called TRACEr--technique for the retrospective and predictive analysis of cognitive errors in air traffic control (ATC). The paper firstly considers the need for an HEI tool in ATC, and key requirements for the technique are noted. The technique, which comprises a number of inter-related taxonomies, based around a simple cognitive framework, is then described. A study concerning a real-world application of TRACEr is outlined-the evaluation of several options for reduced separation minima in unregulated UK airspace. In this study, TRACEr was used predictively and retrospectively, looking forward to pre-empt potential problems and looking back to learn from experience. The paper concludes that TRACEr is a valuable aid to design, development and operations in UK ATC, and has indeed been used as a basis for further applications in ATC both in Europe and the USA.