A method for automatically determining a potential transmission region, comprising: acquiring multiple binary indications for a direct line of sight between a transmitter and an airborne vehicle respective of multiple geo-positions of the airborne vehicle; acquiring each of the multiple geo-positions respective of each of the multiple binary indications for the direct line of sight; for each one of the acquired geo-positions, determining a layer of access respective of topographical data for the geographical region and the acquired geo-position, as a subset of the geographical region that includes at least one potential point defining a potential line of sight between the transmitter and the airborne vehicle, thereby determining multiple layers of access; determining an intersection of the multiple layers of access; and determining, from the intersection, the potential transmission region respective of the transmitter and the geo-positions of the airborne vehicle.