A compact spotting scope includes a housing with an outer surface having a grasping region sized and shaped to fit in a user’s hand. The turbine nozzle may include an airfoil with a leading edge and a trailing edge and a flow fence extending from the leading edge to the trailing edge. The sliding ends of the supporting arms are slidably engaged in two respective sliding channels defined in a supporting base. Identifying an obstacle in dependence upon the future position may also include depicting an anticipated flight of the UAV with 3D computer graphics in dependence upon the future position and identifying an obstacle in dependence upon the depiction of the anticipated flight. If the user is truly who they purport to be, their interpretation will match the electronic model, thus authenticating the user.