The airborne launch vehicle, studied in this article, has to find an appropriate route to reach the mission goal, considering environment requirements and system constraints, for mission safety and efficiency. A method for three-dimensional waypoint generation based on an improved version of the A* algorithm with avoidance of detected obstacles is presented in this article. As the mission proceeds, the information about the environment is regularly updated. This information is considered in the mission plan, yielding a revised sequence of waypoints, to reach one or multiple goal points, depending on their order of priority. The output of the algorithm is twofold: a dynamic waypoint generation and a shortest route refined regularly. Diverse obstacles such as turbulence zones, no-fly zones, storms, etc., are considered in the flight plan as soon as they are detected. Their locations and shapes are introduced into the path search space. The improved A* capabilities are tested via simulation in different scenarios.