*3.2. Analysis of Subjective Workload Scores*

Once the variable associated with reaction time had been discarded, the approach was repeated while considering the workload values recorded by the participants. A combined representation of the exercise design profile and superimposed subjective workload values was created.

Figure 4 presents a combined representation of the designed taskload profile and superimposes the workload values assessed by each participant.

The rationale behind the plots is the same as in the case of reaction time. The only difference is that, in this case, the secondary axis presents the workload values on a scale of 1 to 5.

In addition to the series identifying each of the participants, an additional series of data points has been included in the graphs. The values indicated with an orange star correspond to the mean values of the six participants in each of the moments where the workload is evaluated. As can be seen, in general, the values evaluated by each of the participants are closer to the mean in the first evaluations of the exercises and in the final minutes. In the middle minutes of the exercise and in the intermediate minutes of the taskload cycles, the values assessed by the participants are more dispersed due to the different actions implemented by the participants, especially in the conflict resolution processes.

**Figure 4.** Combined representation of the designed taskload profile of the exercises together with subjective workload assessments for the six participants. The first row of graphs presents Exercise 1 on the left and Exercise 2 on the right. The second row presents the data from Exercise 3 on the left and Exercise 4 on the right.

Unlike what happened in the case of the reaction time variable, the workload values evolve throughout the exercise. The initial hypothesis in this case is that the highest subjective workload values are reached in minutes when the designed taskload is highest. However, in general, this relationship is not observed.

The fact that workload values evolve over the course of the exercise makes them a variable of interest in the study. After the combined graph analysis, the results obtained are as follows:

• The general tendency of the participants is to assess the highest workload values out of phase with the designed taskload. This is particularly clear in the graphs of Exercise 1 and Exercise 3. The reason for this is that events that have a higher value of taskload associated with them appear to have a longer duration than in the designed taskload profile. Therefore, participants must implement actions to deal with these events for longer periods of time. Depending on the actions selected by each participant, especially in conflict resolution processes, the taskloads of more complex events can influence the workload of ATCOs for longer periods of time.


All of the above leads to the conclusion that the designed taskload is not a good reference. This profile was unique for each of the exercises. However, the decision-making process of each ATCO and the conflict resolution strategies used are specific to each controller.

Therefore, in order to explain the workload values evaluated by each of them, it is necessary to compare these values with a specific taskload profile for each participant and each exercise.

Analysis of the graphs in Figure 4 leads to the conclusion that the actual taskload experienced by each controller was different from the designed taskload. Therefore, it is necessary to determine the actual events that took place in the simulation for each participant so that a taskload reference representative of what actually happened may be obtained.

To find out which events took place during the simulations and at what time, the radar screen recordings of each controller were examined. The steps in the methodology to obtain the actual profile were the following:

	- a. The first event is the change of flight level. Some participants, upon identifying that two aircraft were about to encounter a conflict, would anticipate the situation and change the flight level of one of the aircraft before being alerted by the conflict detection tool. This event was assigned a base score of 2 points.
	- b. The second event is the change of speed. As in the previous case, some participants detected in advance that an overtaking conflict was going to occur. In this case, some participants considered that the easiest way to resolve it was to change the speed of one of the aircraft involved. Since the taskload induced is similar to that of flight level changes, this event was also scored with a base value of 2 points.
