# Implementing and Testing a U-Space System: Lessons Learnt
## 5 Tests  
This section describes the flight tests performed by Arquimea and INTA. Prior to these exercises, there were simulations and real flights to test the system. Other planned tests in maritime ports could not be executed in the time-frame of the project in the end and were only evaluated in simulations. The tests for the use cases performed by Arquimea included three tasks: bird shepherding to avoid bird strikes in airports, airport perimeter surveillance to detect potentially dangerous intrusions and runway inspection to detect possible debris that could damage the airplanes during taxing, take-off and landing maneuvers. Arquimea did the tests with the fixed-wing UAV they used in their bird shepherding services (Figure 20) and they performed tests including at the same time a different number of simulated drones in the vicinity (Figure 21). The validation included the use of the smart link switcher developed by UC3M in the work package focused on the communication needs. Both the GCS and the UAV, with its 4G link, reported to the U-space. During the flights, some errors in the reporting lead to the UTM to trigger deviation warnings (Figure 19). This unveils another research need. Since this kind or errors can lead to deconfiction procedures, with possibly an impact in the performance of the rest of the traffic and on safety, it is necessary to minimize the reaction to false positives, by providing some margin of flexibility in the expected reporting, within a margin of safety, before triggering a warning; otherwise, by finding alternative ways to verify the reliability of unexpected report values. While UC3M developed different deconfiction modes for their path planner during the project, only one of them was used in the flight tests and this one deconficted the traffic, basically moving it to different altitudes. Therefore, Arquimea highlighted the need of working with reliable and coordinated altitude references. Figure 21: Arquimea tested in the aerodrome Air Marugán (Segovia, Spain) with one real fixed wing and some others simulated flying at the same time. Figure 20: Arquimea used their Sheperd UAV in the flight tests. INTA validated the U-space solution executing missions with tasks of ground traffic surveillance and support to medical first responders. In the first case, this required the drones to move to specific segments of different roads, and there freely move and position to inspect the traffic in the most convenient way (Figure 22). Therefore, the flight plan should make it possible to define the trajectory to the area of interest, then define a geo-cage there, and then subsequently a trajectory to another point with its geo-cage of interest or the path back home. However, the path planning service would not support this kind of flight plan configurations, and the end of a trajectory was expected to be the ground, not a floating geo-cage. This can be seen in Figures 23 and 24, in which the trajectory assigned by the planner ends on the ground but not the one requested (the draft trajectory) or the one finally flown. The deviation between the altitude assigned for M302 and that flown had to do with a preventive increase to avoid some high trees which probably were not reflected in the elevation map used by the path planner. The alternative was to create a procedure to satisfy this kind of needs during the flight; this is the procedure described in the Tactical Conflict Resolution section. INTA would request a simple plan to the point of interest. Once there, they would cancel the ongoing flight to fly in a previously requested geo-cage in that place (Figure 25). After performing the inspection tasks, they would request a new plan to move to the next point of interest or back home. While this made it possible to execute the required mission with the same path planner, UC3M had to implement the possibility to start/end the flights from/to a specified altitude. Figure 26 shows the moment of this exercise when two drones are in their destination geo-cages recording the ground traffic.