## 3 The Joint Technical Activity: Emergency UAS-Based Aerial Photogrammetry
### Test Site Description and Concept of Operations
\begin{table}
\begin{tabular}{l l} \hline \hline \multicolumn{2}{l}{**Strategic Risk Mitigations**} \\ \hline - & Activation of a dedicated NFZ on D-flight portal (red in Figure 6, top left), authorized by the ENAC; \\ - & Start of the flight operations only after authorization from the UAS CCT/CCOA to the CB; \\ - & UASs equipped with real-time remote identification (Pollicino tracker, [39]—Figure 6, top right and bottom left); \\ - & Common communication phraseology; \\ - & Coordinated simultaneous flight strategy (schematically reported in Figure 7); \\ - & Pre-mission on-site briefing (Figure 6, bottom right) to check the main aspects (e.g., team ID, planning parameters, radio connection, team equipment, \(\ldots\)); \\ - & Trained and qualified person with dedicated role at the CB. \\ \hline \multicolumn{2}{l}{**Tactical risk mitigations**} \\ \hline - & Constant communication via radio (two different frequencies) and mobile phone: UAS CCT-CB and CB-UAS teams; \\ - & Real-time monitoring of the UAS tracker (green in Figure 6, top left) and air manned traffic services at the CB (information displayed on a big screen installed on operational vehicle at the CB) and at the UAS CCT; \\ - & Flight UAS control mode: automatic and manual operation (the pilot is always able to take control of the UAS); \\ - & UAS pilot with at least IT-STS license + payload-trained assistant; \\ - & UAS team of three-quarters trained persons: pilot + payload assistant + visual \\ - & observer/radio assistant/dataset analyst; \\ - & All the flights planned carried out in VLOS condition and in compliance with daytime; \\ - & UAS termination flight system (at least integrated in the flight controller, like CSC command * of DJI drones). \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Emergency aerial photogrammetry activity: summary of the main risk mitigations applied. Figure 6: Some risk mitigations applied during UAS joint activity: NFZ visualized in D-flight with the drone trajectories in green (**top left**—images courtesy of Topview), drone tracker (**top right** and **bottom left**) and on-site meeting with all the UAS teams (**bottom right**). The following strategy has been adopted, given the presence of simultaneous flights, in order to minimize the risk of collision between adjacent UASs (in addition to the parameters reported in Table 1):  
* Sub-area of survey clearly refined by a kml file imported in the flight planning software used by each UAS team when possible;
* Automatic waypoints flight trajectories almost parallel to the shortest dimension of the entire area, always proceeding from northwest to southeast (as schematically reported in Figure 7);
* Take-off, landing and return-to-home (RTH) points within the boundary of each assigned sub-area;
* Different RTH flight height: 120 m for sub-areas 1, 3 and 5 (red, green and orange in Figure 3) and 90 m for sub-areas 2 and 4 (yellow and purple in Figure 3);
* Low battery level warning set to 30%. Once each team reached a suitable position in the assigned sub-area, the operative procedure adopted between the UAS teams and the CB (constant communication ensured mostly via radio) was based on the following main steps:  
1. Check of the radio signal;
2. Transmission of the take-off position of each team (via WhatsApp);
3. Communication of the \"ready-to-take off\" status by each team;
4. Once feedback #3 has been received from each team and after flight authorization from the UAS CCT/CCOA, the CB proceed to order the \"GO to take-off\" firstly to Team5 (orange area in Figure 3);
5. Only after Team5 has been informed about the start of its automatic waypoint mission, the CB proceeds to order the \"GO\" to Team4 (purple area in Figure 3) and so on until Team1. In this way, a proper spatial horizontal buffer between the adjacent drones has been guaranteed (considering the limited extension of the overlap areas with respect to the whole dimension of the sub-areas).