16. Without prejudice to Article 37(2), point (a), of this Regulation and to Articles 44 and 46 of Regulation (EU) 2018/1139 and the delegated and implementing acts adopted on the basis thereof, Member States shall have the complete competence for the development, approval and establishment of the routes and airspace structures for the airspace under their responsibility. In that regard, Member States shall take into account air traffic demands, seasonality and complexity of air traffic and of performance plans. Before deciding on those aspects, they shall take due consideration of the needs of airspace users concerned or groups representing such airspace users and military authorities as appropriate.