Air navigation service providers may avail themselves of the services of other service providers that have been certified F1in accordance with Article 7.

Air navigation service providers shall formalise their working relationships by means of written agreements or equivalent legal arrangements, setting out the specific duties and functions assumed by each provider and allowing for the exchange of operational data between all service providers in so far as general air traffic is concerned. Those arrangements shall be notified to the national supervisory authority F2....

In cases involving the provision of air traffic services, the approval of the F3the national supervisory authority shall be required. In cases involving the provision of meteorological services, the approval of the F3the national supervisory authority shall be required if F4it has designated a provider on an exclusive basis in accordance with Article 9(1).