This article provides some tips for planning a Beyond Visual Line of Sight (BVLOS) flight.
For the special case where you have to fly behind a mountain or tall building (i.e., there is a mountain or building reaching higher than the flight altitude and standing in between you and the flying drone), you have to adjust the "minimum RTH altitude" to ensure WingtraOne will not collide with the mountain in case RTH is triggered while being behind the mountain. Adjust "minimum RTH altitude" to the height difference between take-off and the highest point of the mountain plus a sufficient margin (e.g., plus 50 m). In order to perform such a flight, you likely have to increase the "connection loss timeout" (see: Safety parameters) and will fly blindly. Such a flight is considered highly risky—make sure you know what you are doing.