The future solution for the increasing air traffic density appears to be the free flight for which each airplane will have the possibility to choose its own trajectory and to follow it with only minor ground air traffic controllers' guides. The present paper deals with global collision avoidance which aims at separating aircraft taking into consideration the global traffic in a given area, contrarily to most of the existing approaches which are concerned with local traffic alone. The paper proposes a modeling of the global collision avoidance problem in the free flight context, in the horizontal plane, as a constrained optimization problem. A simulation example is performed in the end which shows the suitability of the proposed approach.
