*2.3. Validation Trials and Setup*

The validation was conducted in the form of real-time HITL simulations and focused on the coordination and guidance of arrival streams (especially the 3D-FMS aircraft) within the novel E-TMA concept and supporting tools. The ATCO worked as a director (feeder). All necessary actions normally done by the executive (pick-up) role were fulfilled by the simulation pilots independently. This included, for example, early decent clearances for the 3D-FMS aircraft. Thereby, the 4D-FMS aircraft were untouchable as soon as the negotiation process was completed. This means that the ATCOs were not actively participating in the negotiation process and not directing these aircraft through their assigned flight paths. During the trials, the ATCO was in charge of both independent parallel runways at EDDM. A within-subjects design with the factor "share of 4D-FMS equipped aircraft" was used to examine the dependent variables flown distance, number of landed aircraft, mental workload, perceived safety and situation awareness [39]. Additionally, feedback about the improved assistant tools was received. By evaluating the dependent variables, the targeted environmental impact was recorded.

The trials were structured into two HITL simulations campaigns. This paper focuses on the results of the final second campaign. The first HITL simulation campaign took place in May 2022. The outcome of this campaign provided minor adjustments and improvements for the simulation setup and procedures which were implemented in the second campaign. The second HITL simulation campaign took place in September 2022. Five male ATCOs participated in the second campaign, with an age ranging between 28 and 44 years (M = 36.8, SD = 8.12) and with 2 to 18 years (M = 10, SD = 7.18) of work experience. One of the five ATCOs had used similar supporting tools or concepts before the simulation in the first HITL simulation campaign in May. Nevertheless, the participant's data were included in the final analysis, as no large training effects were expected. Due to the limited sample size, N = 5, the data and results were analysed on a non-parametric level, providing only first indicators.
