Currently, Air Traffic Control is responsible for the separation of air traffic in our limited airspace. To facilitate the continuing growth of air traffic, an ambitious plan is to give the responsibility of the separation task to the pilots of the aircraft. The behavior of existing conflict resolution methods within this decentralized approach is not completely understood in multi-aircraft conflict scenarios. This research proposes the usage of the Solution Space Diagram, constructed from velocity obstacles, as an automated, horizontal conflict resolution method. With the aid of fast-time simulations, the performance in terms of safety, stability and efficiency of the method using the Solution Space Diagram proved to be worse than an existing method due to coordination issues and the diagram being filled up rapidly under high aircraft densities.