Article 16 Entry into Force 1. This Convention shall enter into force sixty days after the date on which States whose aggregate contributions according to the scale at Annex II amount to at least 85% of the total amount of the contributions have become Parties to the Convention in implementation of Article 15.2. 2. If the requirements for entry into force of this Convention in accordance with paragraph 1 of this Article have not been met 2 years after the date on which the Convention was opened for signature, the depositary shall, at the earliest time possible, convene the Governments of the States which have signed the Convention without their signature being subject to ratification, acceptance or approval or which have deposited instruments of ratification, acceptance or approval. These Governments may then decide that notwithstanding the requirements of paragraph 1 the Convention shall enter into force among them. In taking such a decision these Governments shall agree upon the date of entry into force and a revision of the scale of contributions referred to in Annex II. 3. Following the entry into force of the Convention pursuant to either paragraph 1 or paragraph 2 of this Article, and pending the deposit of its instrument of ratification, acceptance or approval, a State that has signed the Convention subject to ratification, acceptance or approval may take part in EUMETSAT meetings without the right to vote. 4. For any State that, subsequent to the date of entry into force of the Convention, pursuant to either paragraph 1 or paragraph 2 of this Article, signs the Convention without its signature being subject to ratification, acceptance or approval, or deposits its instrument of ratification, acceptance or approval, and for any State that accedes to it, the Convention shall take effect on the date of signature by the said State or on the date of deposit of its instrument of ratification, acceptance, approval or accession, as the case may be. 5. Any State referred to in Article 15.1 that becomes a Party to the Convention shall, in as far as is necessary, make a special payment towards the investments already made for setting up the initial system as described in Annex I, calculated on the basis of the rate of contribution of that State and fixed in Annex II or determined by the Council in conformity with Article 5.2 (b). For any acceding State the special payment in question shall form part of the conditions governing accession, adopted by the Council in conformity with Article 5.2 (a).