Article 15 3.

charges shall be set for the availability of air navigation services under non-discriminatory conditions. When imposing charges on different airspace users for the use of the same service, no distinction shall be made in relation to the nationality or category of the user;

exemption of certain users, especially light aircraft and State aircraft, may be permitted, provided that the cost of such exemption is not passed on to other users;

charges shall be set per calendar year on the basis of the determined costs, or may be set under conditions established by Member States for determining the maximum level of the unit rate or of the revenue for each year over a period not exceeding five years;

air navigation services may produce sufficient revenues to provide for a reasonable return on assets to contribute towards necessary capital improvements;

charges shall reflect the cost of air navigation services and facilities made available to airspace users, taking into account the relative productive capacities of the different aircraft types concerned;

charges shall encourage the safe, efficient, effective and sustainable provision of air navigation services with a view to achieving a high level of safety and cost-efficiency and meeting the performance targets and they shall stimulate integrated service provision, whilst reducing the environmental impact of aviation. To that end, and in relation to the national or functional airspace block performance plans, national supervisory authorities may set up mechanisms, including incentives consisting of financial advantages and disadvantages, to encourage air navigation service providers and/or airspace users to support improvements in the provision of air navigation services such as increased capacity, reduced delays and sustainable development, while maintaining an optimum safety level.