During the last few years, several concepts concerning the delegation to the flight crew of some tasks currently performed by the air traffic controllers have emerged [3]. Among these new ideas, relative guidance has appeared to be of some interest to contribute to the enhancement of air traffic capacity [1] though it rises hard technical challenges. Indeed, this kind of manoeuvre appears difficult to perform manually, and may induce an excessive increase of the flight crew workload, thus requiring a new on-board automated function, as suggested in [6]. This paper aims at providing some technical insights into an airborne relative guidance control system designed to perform merging manoeuvres and to maintain station keeping behind a designated aircraft. The investigated approach is based on flatness control. This is a recent nonlinear control design approach which is useful in situations where explicit trajectory generation is required [5]. The interest of such an approach is that it tackles the separation between the leading and the trailing aircraft to safely manage the whole manoeuvre. Performances based on a case study including wind are also discussed in this paper. Note that our goal is to show the feasibility, from the pilot?s point of view, of an automated relative guidance manoeuvre generator and, though promising, further refinements and extensive validation are indeed needed.