Carl Westin

46 First empirical insights 3-3-3 Task Participants were given two main tasks: resolving conflicts and clearing aircraft to their intended exit point. A continuously updated performance score reflecting these two task parameters was included to prevent scenario recognition and early detection of the designed conflict, in addition to keeping participants focused and motivated. To warn participants of short-term conflicts, an auditory alert was trig- gered, and the aircraft involved in the conflict were displayed in red. To vector an aircraft, a participant used a computer mouse to click on an aircraft of interest, drag the velocity trend vector to a new conflict-free area on the heading ring (a clear and “safe” area outside the red/yellow conflict regions), and press the ENTER key on a keyboard to implement the vector. If the aircraft were to turn ten degrees to the right, it would enter into a short term (0-2 min look ahead) conflict, whereas a ten degree turn to the left would introduce a medium term (2-5 min look ahead) conflict. Short and medium term conflicts were depicted as red and yellow heading band segments, respectively (for reasons of reproduction, these appear as dark and light grey here, respectively). Speed solutions were accomplished by scrolling the mouse wheel, which de- picted a change in the SSD diameter (increasing or decreasing the diameter). No- tice that there is a coupling between speed and heading options, such that changes in speed of a given aircraft impact the size and position of safe and conflict regions. In addition, speed and heading could be combined into one solution. The interaction between SSD heading and speed manipulations is difficult to depict statically, and so is not presented here. 3-3-4 Traffic scenarios and designed conflicts The simulation consisted of short (two-minute) level en-route traffic scenarios based on a squared airspace equal in size (50 x 50 nmi). Sixteen traffic scenarios were used, divided by four groups of four “repeated” baseline scenarios each (labeled Scenarios 1 through 4). Each group was based on a baseline scenario, rotated in different angles to create three variants (labeled 1A through 1D; 2A through 2D etc). Entry/exit points were renamed for each rotation. As such, each group was based on a different traffic scenario, with the four scenarios in each group being identical, except for their rotation and entry/exit point names. Together, these procedures reduced potential confounding factors, and ensured that initial complexity was the same across scenarios, facilitating comparison between low and high complexity conditions. Moreover, this method maintained aircraft geometries through scenario rotations in which the relative trajectories and closure angles of aircraft were kept constant.