58 STAT.] DENMARK-AIR TRANSPORT SERVICES-DEC. 16, 1944 party granting the rights shall, subject to Article 6 hereof, be bound to give the appropriate operating permission to the airline or airlines concerned; provided that the airline so designated may be required to qualify before the competent aeronautical authorities of the con- tracting party granting the rights under the laws and regulations normally applied by these authorities before being permitted to engage in the operations contemplated by this agreement; and provided that in areas of hostilities or of military occupation, or in areas affected thereby, such inauguration shall be subject to the approval of the competent military authorities. (b) It is understood that either contracting party granted com- mercial rights under this agreement should exercise them at the earliest practicable date except in the case of temporary inability to do so. ARTICLE 3 In order to prevent discriminatory practices and to assure equality of treatment, both contracting parties agree that: (a) Each of the contracting parties may impose or permit to be imposed just and reasonable charges for the use of public airports and other facilities under its control. Each of the contracting parties agrees, however, that these charges shall not be higher than would be paid for the use of such airports and facilities by its national aircraft engaged in similar international services. (b) Fuel, lubricating oils and spare parts introduced into the territory of one contracting party by the other contracting party or its nationals, and intended solely for use by aircraft of such other contracting party shall be accorded national and most-favored-nation treatment with respect to the imposition of customs duties, inspection fees or other national duties or charges by the contracting party whose territory is entered. (c) The fuel, lubricating oils, spare parts, regular equipment and aircraft stores retained on board civil aircraft of the airlines of one contracting party authorized to operate the routes and services de- scribed in the Annex shall, upon arriving in or leaving the territory of the other contracting party, be exempt from customs, inspection fees or similar duties or charges, even though such supplies be used or consumed by such aircraft on flights in that territory. 1459 Exercise of commer- cial rights. Charges for use of facilities. Duties on fuel. lubricating oils and spare parts. Post, p . 1461. ATICLE 4 Certificates of airworthiness, certificates of competency and licenses issued or rendered valid by one contracting party shall be recognized as valid by the other contracting party for the purpose of operating the routes and services described in the Annex. Each contracting party reserves the right, however, to refuse to recognize, for the pur- pose of flight above its own territory, certificates of competency and licenses granted to its own nationals by another State. Recognition of va- lidity of certain cer- tificates and licenses. Post, p. 1461.