*4.1. Case Study and Generalised Results*

#### 4.1.1. Case Study

Following all the steps in the methodology, the actual taskload profiles of each of the participants were constructed and analysed one by one. As an example, this subsection explains the detailed analysis of one of these actual taskload profiles. Exercise 1 of Participant 5 (ID5) was selected to be the case study.

After reviewing the radar screen recording of Exercise 1 and studying the decisions made by Participant 5, a total of 47 absolute events were identified, as well as the start and end times of each event.

For these absolute events, the taskload derived from aircraft monitoring was added. From these data, a bar chart representing the actual taskload profile was constructed and compared to the designed taskload profile.

The combined plot of both diagrams can be seen in Figure 5. For each minute of simulation, the green bars represent the designed taskload and the blue bars represent the actual taskload.

When comparing the two bar charts in the previous figure, it can be seen that the taskload distribution is different in the simulated exercise. In addition to the fact that the taskload values per minute of simulation are different, it can also be seen graphically that the taskload distribution in each of the cycles is not maintained.

The designed taskload profile was symmetric. However, symmetry has been lost in the actual taskload, with the highest taskload values being reached in the second part of the exercise.

Table 2 shows a comparison of the most relevant data for each of the designed and actual profiles.

The first row of the table above presents the total taskload values for each of the cases. The taskload profile of the actual exercise is higher than the designed profile. The first conclusion is that Participant 5's simulation was a more difficult Exercise 1 than the one that had been initially designed.

The next two rows compare the scores associated with the absolute events and the monitoring event (defined per minute for each aircraft).

**Figure 5.** Combined representation of the designed taskload profile (green bars) and the actual taskload profile (blue bars) for Exercise 1 of Participant 5.


**Table 2.** Comparison of the most relevant data that characterise the designed and actual taskload profiles.

As can be seen, in the case of this participant, the taskload associated with the absolute events is higher than that of the design. This is due to the fact that a greater number of events appear in the simulation than those initially designed, fundamentally due to the resolution of conflicts. Specifically, the conflict that occurs at 00:10:41 is resolved by changing the flight level of one of the aircraft. As the exercise progresses, this aircraft must be returned to its original flight level in order to comply with the flight plan of its flight progress strip. In the same way, in order to resolve the conflict that takes place at 00:35:00, several vectoring events are required, as the first one is insufficient in terms of respecting the separation minima between aircraft.

In contrast, the monitoring score is slightly lower. This is explained by the fact that the participant handed over some aircraft earlier than planned in the design. Therefore, they spent less time in the sector.

The maximum designed taskload was 7.425 points. The most significant difference in the table is that the maximum taskload that occurred in the exercise was 11.600 points.

In the design, the minute with the maximum taskload was foreseen to be minute 11. Minutes 33 and 36 had a similar taskload associated with them, although slightly lower than the maximum. These high taskload values are associated with the occurrence of design conflicts in the exercise.

In the case of this specific participant's taskload, the highest value was reached at minute 35. This high value is explained by an accumulation of events. Some of them have a taskload value that is not too high. This is the case with respect to the identification and takeover of an aircraft. The problem is that in this exercise, they gather in the same minute in which the participant identifies and starts to resolve a conflict.

Finally, the last row compares the number of absolute events. In the case of the simulated exercise, three additional events occurred compared to the design. Specifically, they were events associated with conflict resolution, as the participant had to try different strategies due to the first not being effective.

Once the actual profile of the participant has been obtained and analysed, it needs to be compared with the subjective workload values assessed by the participant. A combined graph of the participant's actual profile and the subjective workload values assessed can be seen in Figure 6.

**Figure 6.** Comparison between the actual taskload profile obtained for Exercise 1 of Participant 5 and the workload values assessed by the participant during the simulation.
