Artikel 4

In order to prevent discriminatory practices and to assure equality of treatment, it is agreed that:
(a) Each of the contracting parties may impose or permit to be imposed just and reasonable charges for the use of airports, and other facilities. 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 or taken on board aircraft in the territory of a 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 with respect to customs duties, inspection fees or other national duties or charges imposed by the former contracting party, treatment not less favourable than that granted to national or other foreign airlines engaged in international airtransport.
(c) Aircraft operated on the agreed services and supplies of fuel, lubricating oils, spare parts, regular equipment and aircraft stores retained on board civil aircraft of the airlines of the contracting parties authorized to operate the routes and services described in the Annex shall upon arriving in or leaving the territory of the other contracting party, be exempt from customs duties, inspection fees or similar duties or charges, even though such supply be used or consumed by such aircraft on flights in that territory.
(d) Goods so exempted, may only be unloaded with the approval of the customs authorities of the other contracting party. These goods, which are to be re-exported shall be kept until re-exportation under customs-supervision.