Usage of Unmanned Aerial Systems (UASs) is widely diffused and will involve different aspects of our life in cities in the future. Nowadays UASs are used to accomplish several applications: data collections, surveillance, logistics, search and rescue, to name a few. Despite the rapid growth of this technologies, currently most of the National Aviation Authorities impose strict regulations to the UAS missions pratically hindering autonomous flights. The majority of these operations must be performed in Visual Line-Of-Sight (VLOS) and, to guarantee operations over urban area, they require the use of harmless drones, even if in the recent years the authorities permit to perform operations also Beyond Visual Line-Of-Sight (BVLOS) even over cities.