## 1 Introduction  
Natural disasters, such as earthquakes, floods and wildfires, are likely to bring extensive damage, even over large areas, causing human, economic, material and environmental losses. Rescue activities are organized depending on the morphology and the extension of the affected area and on the type and severity of the calamity ([1]). Nevertheless, the implementation of such activities is hindered by the lack of information regarding the most affected territories and the actual conditions of infrastructures and transportation networks. To deal with time and to decrease the number of casualties and economic losses, an effective network-based disaster management system (DMS; [2]) is needed, within which crucial roles are played by the distribution and collection of information, the prioritization of rescue and technical intervention, the disaster area monitoring as well as continuous communication with the coordination centers. Aerial remote sensing is becoming an important resource for DMS authorities to deal with some of these issues and to increase the understanding of the territory in the aftermath of a large-scale disaster ([3]), when it is crucial to have a quick and updated appraisal of the situation (i.e., extension of impacted area, limitations for the rescue operations). Within this context, unmanned aircraft systems (UASs) are being progressively tested to support civil protection in the post-disaster activities related to humanitarian relief, damage mapping ([4; 5; 6; 7; 8; 9; 10; 11; 12]) and, in general, the mitigation of disaster impacts ([13; 14]). Landslides monitoring ([15]), logistic or search and rescue operations ([16; 17; 18; 19; 20]), ground network communications restoration ([21; 22; 23]) and damage assessment (also assisted by AI technologies) for the usability evaluation of structures [24; 25; 26; 27; 28; 29]) are some of the specific fields of application. Although the majority of the above-mentioned applications involve the use of single UAS (sometimes custom-made for research goals), the employment of multiple UASs (fleets) supporting emergency management is recognized as a powerful solution by different works and on-site applications ([21; 30; 31; 32]). UASs have many advantages in disasters management ([3; 33]): low operating and acquisition cost, limited exposition of pilots to dangerous areas, rapid placement and reaction time, scalable intervention and access to otherwise inaccessible locations. In addition, they can be equipped with a large variety of sensors, from LiDARs to sensors to measure smoke composition, wind speed, to name a few. Nevertheless, the use of UASs, especially if operated simultaneously, involves a series of technical and operational challenges, still deserving investigation and testing, also keeping in mind the compliance with the regulatory restrictions, which is an additional not-negligible aspect concerning operations with drones. In particular, according to the current European regulation ([34; 35]), when an \"emergency response effort is ongoing\", UAS operators are allowed to fly only under specific permission issued by the \"responsible emergency response services\". Some of the crucial aspects are in fact the interaction with the national aviation authorities in the view of a standardized activation procedure for UAS teams and the safe and coordinated management of the shared airspace (considering the likely presence of manned vehicles). Data collection, coordination and communication, safety issues, interaction within the emergency management system and use of aerial space are, amongst others, the transversal main challenges/objectives addressed in the present paper in the context of the technical exercise named \"EXE.Lomb.Est 2023\", focused on the use of drones for civil protection activities that took place on 9-14 October 2023.