Objective Job Difficulty,Behavioural Response,and Sector Characteristics in Air Route Traffic Control Centres∗

Abstract

Two thousand observations on 47 radar sectors in Boston and New York were used to determine the principal behavioural stressors in the air traffic control environment. Predictor variables included peak traffic. mean airspeed, sector area, sector type, radio-communication time, and theoretically derived control load factors.

Expert observers rated the degree of activity and behavioural arousal of ATCs working the 47 radar sectors at the same time the objective measures were made. These ‘pace’ ratings were significantly related to peak traffic count and duration of radio-communications.

The control load factors were not related to behavioural responses. Statistical analyses indicated several refinements for the definition and measurement of the control load factors, For example, airspace control load was reliably estimated by sector type and number of transitioning planes, while co-ordination control load was most appropriately estimated by duration of radio-communications

These results suggested that estimations of workload may be made by a relatively few objective measures, and that at least one estimate of individual's behavioural responses, i.e.. pace ratings, can be predicted by peak traffic counts.     

Workload and psychophysiological stress reactions in air traffic controllers

Interactions between workload and psychophysiological stress symptoms were investigated in a population of 205 predominantly male air traffic controllers (ATCs) from the area control centre (ACC) and the airport control tower (TWR) in Zurich and Geneva. Each subject completed two questioning sessions and two working sessions, the first time during a period of low traffic and the second time during a period of high traffic. For the questioning sessions standardized questionnaires were used. For all investigated working sessions, different aspects of the subjective and objective workload were recorded. Before and after each session, a saliva sample for assessing the concentration of secreted cortisol was taken. The questionnaire parameters represented psychological stress symptoms, such as complaints of physical discomfort, depression, negative self-communication, work-increased anxiety, coping behaviour and subjective rating, and interpretation of various aspects of the working situation. The mean values measured were within the normal range, and only a few significant differences between the two questioning sessions were found. However, about 10 to 15% of the ATCs showed elevated values in psychological stress symptoms to an extent indicating that they might have serious stress problems at work and/or in their private life. The investigated working sessions showed that the ATCs' subjective ratings correspond clearly to their cortisol response and the objective workload. Thus, ATCs' complaints regarding excess work stress should be taken seriously.     

Variations in ATC-Work Load as a Function of Variations in Cockpit Workload

Abstract

The relation between pilots‘ workload and radar controllers‘ workload was investigated. Pilots‘ workload served as the independent variable. It was assumed that a number of levels of workload can be distinguished in a standard airport, traffic circuit under visual flight rules. The dependent variable (controllers’ workload) was measured by response frequency on an auditory binary choice task. Results indicate a rise in radar controllers’ workload in a predicted direction for a number of pilots’ workload levels.     

Human performance assessment of a single air traffic controller conducting multiple remote tower operations

The innovative concept of multiple remote tower operations (MRTO) can maximize cost savings by applying video panorama‐based remote tower working positions, which can facilitate fewer air traffic controllers (ATCO) to provide the air traffic services (ATS) function for more airports. Five subject‐matter experts, qualified remote tower ATCOs, participated in this research work by applying the human error template (HET) and comparing workload between physical tower operations and MRTO using NASA‐TLX (Task Load Index). The results demonstrate that augmented visualization provided sufficient technical support for a single ATCO to perform tasks originally designed to be performed by four ATCOs, however, the demands of the associated multiple tasks induced significant workload. There were significant differences in ATCOs’ mental demand, temporal demand, effort, and frustration between MRTO and physical tower operations. This innovative technology may induce human–computer interaction (HCI) issues that impact ATCO's perceived workload. This creates a need for further research on how to manage ATCO's workload in a multiple remote tower environment. This research work provided scientific evidence that MRTO can achieve the objectives of Single European Sky Air Traffic Management Research program. The findings can be applied to both ATCO training design and remote tower system design.     

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.     

Cognitive process modelling of controllers in en route air traffic control

In recent years, various efforts have been made in air traffic control (ATC) to maintain traffic safety and efficiency in the face of increasing air traffic demands. ATC is a complex process that depends to a large degree on human capabilities, and so understanding how controllers carry out their tasks is an important issue in the design and development of ATC systems. In particular, the human factor is considered to be a serious problem in ATC safety and has been identified as a causal factor in both major and minor incidents. There is, therefore, a need to analyse the mechanisms by which errors occur due to complex factors and to develop systems that can deal with these errors. From the cognitive process perspective, it is essential that system developers have an understanding of the more complex working processes that involve the cooperative work of multiple controllers. Distributed cognition is a methodological framework for analysing cognitive processes that span multiple actors mediated by technology. In this research, we attempt to analyse and model interactions that take place in en route ATC systems based on distributed cognition. We examine the functional problems in an ATC system from a human factors perspective, and conclude by identifying certain measures by which to address these problems. This research focuses on the analysis of air traffic controllers' tasks for en route ATC and modelling controllers' cognitive processes. PRACTITIONER SUMMARY: This research focuses on an experimental study to gain a better understanding of controllers' cognitive processes in air traffic control. We conducted ethnographic observations and then analysed the data to develop a model of controllers' cognitive process. This analysis revealed that strategic routines are applicable to decision making.     

Analysis of the performance characteristics of controllers’ strategies in en route air traffic control tasks

For addressing human factor issues in the air traffic control (ATC) domain, further comprehension of controllers’ working methods during actual work is required. The objective of the present research is to analyze the performance characteristics of control strategies, which can be a major means to manage a traffic situation and workload for controllers, by using our process visualization tool of ATC tasks called COMPASi (COMPAS in interactive mode/COMPAS: COgnitive system Model for simulating Projection-based behaviors of Air traffic controllers in dynamic Situations). The computer-based simulation using COMPASi has clearly demonstrated the performance differences in the types of control strategies derived from a high-fidelity human-in-the-loop simulation (HITLS) for safety, efficiency of completing ATC tasks, and fuel economy of aircraft in a specific situation, and also differences in their tolerance of situational variability. The analysis results have been supported by performance evaluations carried out by ATC training instructors. In addition, a comparative analysis between simulation results under several simulation conditions by COMPASi and evaluation results by the instructor has strongly implied that the tolerance for the variability of situations might be a major factor in selection of control strategies by a controller. These contributions of the present research may be useful for practical purposes such as further improvement of education and training for controllers.     

How job satisfaction can influence air traffic controllers' backup‐providing behavior in parallel runway operation

Team members can request and provide backup from one to other members, which can help teams with high workload achieve dynamic workload optimization at the group level. However, studies on this issue are limited, especially on real‐world high‐risk operations. This study explored how to approach air traffic controllers make backup decisions in the dependent parallel approach operation. In this study, we focused on how individual difference factors can influence the controller's backup willingness and decision. Forty licensed controllers performed 32 simulated scenarios varied in their own task load, the backup recipients' task load, and shorter taxing possibility. We also measured their job satisfaction and work experience. Multilevel regression analyses showed that controllers with a higher level of job satisfaction were more likely to provide help to their colleagues. Moreover, when their job satisfaction was high, they were less sensitive to the seemingly inappropriate request, but they only used their additional resources to help others. The findings were discussed in the literature of teamwork and aviation safety.     

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.     

基于遗传算法组合预测模型的空域流量预测系统构建

航班总量的持续增长使得航班安全保障的压力不断加大。在空域资源有限、航空管制工作繁重的大型国际机场,航班动态信息的准确、可靠性将为制定有效地管制调配措施提供有力的依据。为了准确预测特定区域中某个航路点在某一时间段的航班流量,给管制人员提供参考,便于提前灵活、合理地制定管制策略,避免空域资源浪费,为各级决策部门制定发展战略与规划提供重要依据。基于不同航班流量信息源建立组合预测模型,通过遗传算法对组合模型的权重值进行优化,并根据西安管制区域构建出了空域流量预测系统的设计构架。     

Comparing display symbology for an advanced air traffic controltower application

Describes experiments that compare air traffic controller performance with two different types of simulated airport radar display formats. The formats differed in the method of presenting aircraft radar returns: analog or digital symbols. Pre-experimental studies examined potential airport tower automation systems and the opinions of various system stakeholders about these automated systems, and then modeled airport operations to discern the impact of these systems on controller workload and airport congestion. Results from the earlier studies helped focus the experiments which concluded that the digital icon format is likely to be better than the analog format at helping controllers accomplish their duties in a timely manner     

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.     

An analysis of relational complexity in an air traffic control conflict detection task

Theoretical analyses of air traffic complexity were carried out using the Method for the Analysis of Relational Complexity. Twenty-two air traffic controllers examined static air traffic displays and were required to detect and resolve conflicts. Objective measures of performance included conflict detection time and accuracy. Subjective perceptions of mental workload were assessed by a complexity-sorting task and subjective ratings of the difficulty of different aspects of the task. A metric quantifying the complexity of pair-wise relations among aircraft was able to account for a substantial portion of the variance in the perceived complexity and difficulty of conflict detection problems, as well as reaction time. Other variables that influenced performance included the mean minimum separation between aircraft pairs and the amount of time that aircraft spent in conflict.     

An analysis of relational complexity in an air traffic control conflict detection task

Theoretical analyses of air traffic complexity were carried out using the Method for the Analysis of Relational Complexity. Twenty-two air traffic controllers examined static air traffic displays and were required to detect and resolve conflicts. Objective measures of performance included conflict detection time and accuracy. Subjective perceptions of mental workload were assessed by a complexity-sorting task and subjective ratings of the difficulty of different aspects of the task. A metric quantifying the complexity of pair-wise relations among aircraft was able to account for a substantial portion of the variance in the perceived complexity and difficulty of conflict detection problems, as well as reaction time. Other variables that influenced performance included the mean minimum separation between aircraft pairs and the amount of time that aircraft spent in conflict.     

Forecasting workload and airspace configuration with neural networks and tree search methods

The aim of the research presented in this paper is to forecast air traffic controller workload and required airspace configuration changes with enough lead time and with a good degree of realism. For this purpose, tree search methods were combined with a neural network.The neural network takes relevant air traffic complexity metrics as input and provides a workload indication (high, normal, or low) for any given air traffic control (ATC) sector. It was trained on historical data, i.e. archived sector operations, considering that ATC sectors made up of several airspace modules are usually split into several smaller sectors when the workload is excessive, or merged with other sectors when the workload is low. The input metrics are computed from the sector geometry and from simulated or real aircraft trajectories.The tree search methods explore all possible combinations of elementary airspace modules in order to build an optimal airspace partition where the workload is balanced as well as possible across the ATC sectors. The results are compared both to the real airspace configurations and to the forecast made by flow management operators in a French en-route air traffic control centre.     

To Intervene or not to Intervene: The Dilemma of Management by Exception

Future air traffic management architectures propose to give aircraft more flight path autonomy and turn the air traffic controller into a manager of exceptions. This article reports on one experiment in a series of studies that empirically explored the cognitive work underlying management by exception in air traffic control. Active practitioners (controllers, pilots, dispatchers) were prepared on the rules of the envisioned system and presented with a series of future incidents, each of which they were required to jointly resolve. Management by exception turns out to trap human controllers in a double bind, where intervening early seems appealing but is difficult to justify (airspace throughput) and carry out (controller workload problems). Late interventions are just as difficult, since controllers will have to take over in the middle of a potentially challenging or deteriorating situation. Computerised decision support that flags exceptions migrates the decision criterion into a device, creating a threshold crossing that is typically set either too early or too late. This article lays out the intertwined trade-offs and dilemmas for the exception manager, and makes recommendations for cooperative human–machine architectures in future air traffic management.     

Aiding planning in air traffic control: an experimental investigation of the effects of perceptual information integration

Prior research examined how controllers plan in their traditional environment and identified various information uncertainties as detriments to planning. A planning aid was designed to reduce this uncertainty by perceptually representing important constraints. This included integrating spatial information on the radar screen with discrete information (planned sequences of air traffic). Previous research reported improved planning performance and decreased workload in the planning aid condition. The purpose of this paper was to determine the source of these performance improvements. Analysis of computer interactions using log-linear modeling showed that the planning interface led to less repetitive--but more integrated--information retrieval compared with the traditional planning environment. Ecological interface design principles helped explain how the integrated information retrieval gave rise to the performance improvements. Actual or potential applications of this research include the design and evaluation of interface automation that keeps users in active control by modification of perceptual task characteristics.     

贵阳数字通播与数字放行系统项目的实施与建设

The DATIS is widely used by global air traffic control system, which is an advanced achievement of automatic air traffic control technology. The large-scale application of DATIS technology will effectively reduce the workload of pilots and improve the ability of excluding human interference, thus providing a basic guarantee for the more effective work of controllers. Based on this, this paper is mainly to introduce the implementation and construction process of the DATIS and DCL systems in Guiyang.     

Applications of Digital Computers to Air Traffic Control in the United States

Digital computers are being applied in large numbers to air traffic control operations in the United States. By the mid-1970's, all U.S. en route traffic control centers and all busy terminals will be equipped with systems featuring digital computers which process flight plans and radar and beacon data into displays for air traffic controllers. Work is underway to further apply computers to such control functions as ground-based conflict prediction, sequencing and spacing, and flow control.