Article 9a 1.

By 4 December 2012, Member States shall take all necessary measures in order to ensure the implementation of functional airspace blocks with a view to achieving the required capacity and efficiency of the air traffic management network within the single European sky and maintaining a high level of safety and contributing to the overall performance of the air transport system and a reduced environmental impact. Member States shall cooperate to the fullest extent possible with each other, in particular Member States establishing neighbouring functional airspace blocks, in order to ensure compliance with this provision. Where relevant, cooperation may also include third countries taking part in functional airspace blocks.