Understanding the type and quantity of tasks an air traffic controller is required to carry out at any one time can reveal the influences on the operator’s ability to safely and efficiently complete their activities.
The Air Traffic Control Task
On the basis of different information sources (e.g., radar screen, paper or electronic flight progress strips, radio and interphone communication), air traffic controllers have to control complex, dynamic, and time-constrained traffic situations in order to identify potential conflicts and risky relationships between aircraft and to be able to resolve them. Therefore, they have to perceive, comprehend, and anticipate multiple characteristics and flight paths of many aircraft while new incoming aircraft create new traffic relationships for evaluation. Diagnosis, decisions on future cognitive activities, and actions are based on these insights into current and anticipated structures of the changing situation.
In an ATC environment, the term situation awareness describes the mental representation of the current and future traffic situations.
There have been numerous studies conducted in the past years analysing the relations between ATC task demand factors and human performance in ATC. The results of this research is summarised in guidelines which are used by many ANSPs to derive absolute values, such as “controller workload” or “sector capacities”.
ATC Task Breakdown
Specifically, human factors elements at the task level are:
Workload: The demands of a task or job role that are imposed on an individual.
Controller workload refers to cognitive workload. It is generally agreed that controller’s workload is a subjective and individual response by a controller to given task load situation, and that either personal factors (e.g. skill, experience, stress) or contextual factors (e.g. time pressure, noise, stressors, distraction, organisational change issues) can all influence workload.
One of the greatest staffing challenges during workload extremes (that is in high/low workload situations) is matching available workforce to the current traffic level. A mismatch between the two can impact controller fatigue and even jeopardise safety. However, it is clear that the high-workload situation is not the only one for concern; low-traffic periods carry their own risks (e.g. reduced vigilance and therefore the possible failure to notice critical events).
Performance Standards: The level of performance at which a staff member is expected to maintain.
The term performance refers to the ability of controllers to carry out their tasks (maintain situation awareness etc.), while maintaining a certain level of effectiveness.
The relationships among workload, performance, and effectiveness are complex and contextually specific.
To determine the performance standards for air traffic controllers, researchers within industry utilise the human performance models which provide a way of addressing these relationships. By building a human performance model that simulates how controllers carry out their tasks it is possible to generate more accurate predictions of future ATC task demands. Furthermore, by taking into account strategies that controllers use to minimize the amount of control activity required to meet their objectives, one can more accurately predict the effects of demands on both mental workload and performance. For example such strategies could be using various scanning methods for identifying potential conflicts, addressing the conflict or building a strategy for addressing it, well before the situation begins to develop.
Roles and Responsibilities: A description of each role and the associated day to day responsibilities.
With assigned specific roles, functions and responsibilities, the controllers interact dynamically and interdependently with the other users within the ATM system, while at the same time needing to maintain the required performance standards.
Task interruption and distraction: Anything (i.e. actions / communications / cognitive mental activity) that breaks the flow pattern of ongoing activities.
Interruptions and distractions are frequently faced by controllers and can lead to significant safety problems.
Interruptions (e.g., due to phone calls, non-standard events and communications) and distractions (e.g., due to a loud conversation among others at the OPS room, ambient noise e.g. air conditioning) do occur. Some cannot be avoided and therefore must be coped with by the controllers. Others can be minimized or eliminated through training, adoption of effective procedures, discipline and the use of good judgment. If the number of interruptions and distractions is not minimized or the impact of residual interruptions and distractions is not controlled, flight safety can be affected. In particular, when a controller is disturbed while monitoring or controlling the aircraft, errors can occur and remain undetected.
The impact of these task factors is further linked inextricably with and influenced by individual factors, such as human capabilities, performance limitations and an individual’s skill and knowledge.
- A Psychological Model of Air Traffic Control and Its Implementation, C. Niessen, S. Leuchter, & K. Eyferth, Centre for Man-Machine-Systems Studies, Technical University of Berlin
- Modeling and Predicting Mental Workload in En Route Air Traffic Control: Critical Review and Broader Implications, S. Loft, P. Sanderson, A. Neal, and M. Mooij, The University of Queensland, Brisbane, Australia