## 4 Flight Test Results and Discussion
### Flight Test Records  
There were 10 flight tests conducted in two locations, with 6 flights for scenario 1 and 4 flights for scenario 2, as recorded in Table 2. It involved 5 UAVs with 4 experienced UAV pilots from our NFU UAV Laboratory. The flight test data was filtered based on the take-off to landing time of the controlled UAV 1. The total flight test time was 71 min and 55 s, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**UAV Parameters** & **Sky Surfer 1** & **Sky Surfer 2** & **Mini Talon 1** & **Mini Talon 2** & **Lanyu E-Fair** \\  & [41] & [42] & [43] & [43] & [44] \\ \hline Type & Glider & FPV glider & V-tail & V-tail & Glider \\ Wingspan & 1420 mm & 2000 mm & 1350 m & 1350 m & 1540 mm \\ Length & 960 mm & 1350 mm & 828 mm & 828 mm & 980 mm \\ Kit weight & 690 g & 1350 g & 400 g & 400 g & 545 g \\ Material & EPO & EPO & EPO & EPO & Balsa wood \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Fixed-wing UAVs used in the flight tests. Figure 8: Two flying locations of the flight tests: (**a**) near Yunlin HSR station (blue icon) and (**b**) NFU Agriculture campus (red icon). which consists of 4607 data points. The flight tests were always conducted in the morning Taiwan time when the wind was relatively calm. The flight data for our analysis came from the log file of the UTM monitoring application, which consisted of flight parameters and conflict detection parameters. The sample of the flight test trajectory from record number 8 is shown in Figure 9. Module 1 of the Remote ID flew in the Sky Surfer 1 and module 2 stayed on the ground. The flight test data is shown in Figures 10 and 11. Each of the data is plotted in three subplots, which describe the flight parameters, detection parameters, and time parameters. Figure 11: Flight test data from Remote ID module 2 of record number 8 in subplots with the sequence discussed above: (**a**) flight parameters, (**b**) detection parameters, and (**c**) time parameters. Figure 10: Flight test data from Remote ID module 1 of record number 8 in subplots with the sequence discussed above: (**a**) flight parameters, (**b**) detection parameters, and (**c**) time parameters. The flight parameter subplots in Figures 10a and 11a indicate that UAV 1 flew at a height between 10 and 50 m and a speed between 10 and 30 m/s. It also shows that UAV 1 executed several turns, as shown by the changes in its bearing and turn rate. However, the UAV 2 stayed on the ground with altitude and speed changes being very small due to noise in the GPS and accelerometer measurements. Due to this noise, the bearing and turn rate fluctuated. This condition is confirmed by the trajectory plot in Figure 8.  
The detection parameter subplots in Figures 10b and 11b show that UAV 1 moved toward the position of module 2 of the Remote ID and then moved out for several rounds to exercise a conflict detection process. Since the location of module 2 of the Remote ID was near the take-off and landing points, the warning level 2 (near-collision event) is shown at the beginning and the end of the plot. At some points during the flight test, the distance between UAVs was closed enough to trigger a detection warning (warning level 1). At this point, the UTM system produced a warning sound and the color changed in the UI display. When the pilot managed to avoid conflict, the warning faded. However, in some events, the UAVs were so close that they penetrated the near-collision area, which was indicated by a near-collision warning (warning level 2). The third set of subplots in Figures 10c and 11c shows the latency time or latency time, which consisted of the broadcast time, query time, and process time. It also shows the interval time between data transmission. At a certain point, the query time was very large, up to 5 s, which, in turn, affected the latency time.