5.—(1) Where the regulator is satisfied that the relevant data is available to it, the regulator (“A”) must—
(a)assess whether the highest percentage of aviation emissions of an aircraft operator without a registered office (“B”) are attributable to the area of a different regulator (“C”);
(b)do so by 14th December in the final year of each trading period; and
(c)make this assessment taking into account data from the beginning of the trading period to the date of the assessment.
(2) Where that assessment shows that the highest percentage of emissions is attributable to the area of C, A must give notice to B and C by 21st December in the final year of the trading period.
(3) Where—
(a)A has given notice under paragraph (2); and
(b)the regulator for the trading period following that notice is not determined under regulation 6,
C is the regulator of B from the beginning of that trading period.