User charges imposed on airlines of the other Party may reflect the full costs incurred by the competent authorities or bodies for the provision of the corresponding airport, airport, environmental, air navigation and aviation security equipment and services at the airport or within the airport system, but shall not exceed them. These costs may include a reasonable return on assets after depreciation. Facilities and services subject to charges shall be provided on an efficient and economical basis. Britain left the EU earlier this year, but remains, in practice, covered by EU agreements and rules until the end of the transition period at the end of this year. The agreement will enter into full force after the conclusion of the procedures of both parties in favor of an international agreement, says the DOT. The Parties plan to apply the Agreement from 1 January 2021. 6. Within sixty days of the appointment of such two arbitrators, they shall appoint by mutual agreement a third arbitrator to act as chairman of the arbitral tribunal; Either Party may, at any time, request in writing the other Party to terminate this Agreement. This communication should be addressed simultaneously to the International Civil Aviation Organization. . . .