A new method for trajectory planning to resolve potential conflicts among multiple aircraft is proposed. The key objective is to take advantage of the new developing technologies, such as satellite navigation and communication, to resolve conflicts cooperatively and efficiently with safety-critical trajectory planning. We start with a brief review of aircraft trajectory planning and conflict resolution methods. Next, a new method and its associated algorithmic development is proposed. The proposed method is based on a probabilistic conflict risk map constructed according to the intention information broadcast by the intruders. A* algorithm is used for a single aircraft to find the cost minimized trajectory. Priority indexing method is implemented to iterate the A* algorithm for all effected aircraft to optimize the trajectory planning. Convergence and computation efficiency characteristics of the proposed method are investigated, followed by several numerical examples to illustrate the effectiveness of the proposed method.