*1.2. Taskload and Workload*

Taskload is a measure associated with the challenge and difficulty faced by a person in completing a task [10]. ATCOs are subject to multiple task demand loads, or taskloads, over time [11]. Another key concept is mental workload. Mental workload reflects the subjective experience of individuals when performing specific tasks in specific environments and under specific time constraints [12].

Taskload and workload are not synonyms. While the concept of taskload refers to external duties, the amount of work, or the number of tasks to be performed by the ATCO, the concept of workload refers to the individual effort made by a person and his or her subjective experience under given conditions [13].

In [14], the authors identify some of the factors that influence the variables of taskload and workload. Factors such as airspace demand, interface demand, and procedure demand influence taskload. On the contrary, some factors that influence workload are skills, strategy, and expertise.

There are multiple approaches to defining the taskload faced by ATCOs. As an example, in [15], a study was conducted to determine whether air traffic control communication events would predict subjective estimates of controller workload and controller taskload measures. There were four taskload components considered in this study: two principal components related to the number and duration of communication-related events and two principal components related to the content of voice communications. This study is an example of the fact that, despite the generic definition of taskload, the way it is quantified and its components vary according to the specific objective of the study.

The authors in [16] discuss a comparison of different complexity metrics related to the ability to match the subjective workload results obtained in a simulation. The definitions of taskload and workload in this reference coincide with the definitions of these terms in this line of research. In the above reference, it is also explained that one of the simplest ways to quantify taskload is to count the number of aircraft present in a sector. Similarly, it is noted that this approach presents limitations, as it does not consider the evolution of aircraft in the sector. The study presented in this paper aims to use a more comprehensive measure of taskload than aircraft counts. To do so, the experiment described in this paper uses event-based taskload as a metric, which results from considering the taskload contribution of the aforementioned set of ATC events.

Based on the definitions of taskload and workload, it can be concluded that taskload is the part of the work demand imposed on the controller purely due to the tasks he/she has to perform [17]. The taskload value of the ATC events included in the research line of this paper is specific to each event. However, the workload perceived by the participants when facing such events will be specific to each person.
