This paper present a new Air Traffic routes generator based on Genetic Algorithms. Due to the traffic growth, direct (and near direct) routes are more and more congested and there is a real need for spreading the traffic on new alternative routes. Those routes have to be different from several operational criteria and must not generate too much extra-distance compared with the direct route. To reach this goal, a GA has been implemented with an efficient sharing which automatically allows the emergence of different alternative routes. This algorithm has been tried on the French airspace and gives realistic operational results.