Latest trends, societal needs and technological advances have led to an unparalleled expansion in the use of Unmanned Aerial Systems (UAS) for versatile civilian and military applications, ranging from simple everyday operations, to the supervision in construction sites, even logistics, among others. Unmanned Aerial Vehicles (UAVs), widely known as drones, are the main components of UAS, and are becoming increasingly popular in such operations, since they reduce costs, they facilitate activities and can increase the granularity of surveillance or delivery. Furthermore, they can pave new ways for the implementation of smart-sensing and navigation functionalities, support automation, safety of operations, prognostics and even forensic analyses. Being an emerging technology, several challenges still need to be tackled in order to make UAS suitable for real-world applications, which impose strict performance, dependability and privacy requirements. In the light of the above, this paper provides an in depth survey of current UAS technologies for Beyond the Visual Line of Sight (BVLOS) UAS operations and highlight the main technological challenges and requirements that arise. We also focus on the emerging and future BVLOS UAS features and the technological advances that render their expansion in various industrial sectors promising.