4.—(1) Subject to the provisions of these Regulations the operator of any aircraft (in whatsoever State it is registered) for which navigation services (not being navigation services provided in connection with the use of an aerodrome) are made available in a specified airspace shall pay to Eurocontrol, in respect of each flight by that aircraft in that airspace, a charge for those services (hereinafter referred to as “the charge”) at the appropriate rate calculated in accordance with regulation 6 of these Regulations.
(2) If Eurocontrol is unable, after taking reasonable steps, to ascertain who is the operator, it may give notice to the owner of the aircraft that it will treat him as the operator until he establishes to the reasonable satisfaction of Eurocontrol that some other person is the operator; and from the time when the notice is given Eurocontrol shall be entitled, for so long as the owner is unable to establish as aforesaid that some other person is the operator, to treat the owner as if he were the operator, and for that purpose the provisions of these Regulations (other than this paragraph) shall apply to the owner of the aircraft as if he were the operator.
(3) The operator of an aircraft shall not be required to pay any charge to Eurocontrol under these Regulations in respect of a flight if he has previously paid to Eurocontrol in respect of that flight a charge of the same or a greater amount under the law of a country specified in column 1 of Schedule 2 hereto.