Concept design is the first phase of the design process, the time needed to make basic decisions that set the specifications for a proposed artifact and begin to determine its ultimate shape. Starting from very general and very high level requirements, a first set of requirements is created, several concepts are evaluated, to the point where a concept can be retained for the detailed design and potentially for a setting-in-production. Like all subsequent design phases, concept design is affected by the concurrent engineering trend with its wide range of stakeholder perspectives and design issues to consider. As conceptual design becomes more demanding, improvements in quality are also required. It is becoming increasingly important that the results of the design concept can be transparently and easily taken into account in subsequent development phases. To better support this first phase of design, the use of model-based systems engineering is studied. This presentation aims at presenting the where and how aircraft concept design could benefit from a systems engineering approach