# The Air Navigation (Carbon Offsetting and Reduction Scheme for International Aviation) Order 2021, Paragraph 4: Method B

Extent: E+W+S+N.I.

(1) The aeroplane operator must use the following formula to compute fuel use according to Method B—
F N = R N−1 − R N ± U N where—
FN = Fuel used for the flight under consideration (i.e. flight N) determined using Method B (in tonnes);
RN–1 = Amount of fuel remaining in aeroplane tanks at the end of the previous flight (i.e. flight N-1) at Block-on before the flight under consideration (in tonnes);
RN = Amount of fuel remaining in aeroplane tanks at the end of the flight under consideration (i.e. flight N) at Block-on after the flight (in tonnes); and
UN = Fuel uplift for the flight considered measured in volume and multiplied with a density value (in tonnes).
(2) The aeroplane operator performing on an ad-hoc basis flights attributed to another aeroplane operator must provide to the latter the fuel measurement values according to the Block-off/Block-on method.
(3) Where an aeroplane does not perform a flight previous to the flight for which fuel consumption is being monitored (e.g., if the flight follows a major revision or maintenance), the aeroplane operator may substitute the quantity RN-1 with the amount of fuel remaining in the aeroplane’s tanks at the end of the previous activity of the aeroplane, as recorded by technical logs.

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Source: https://www.legislation.gov.uk/uksi/2021/534/schedule/2/paragraph/4 (the official version)
Page: https://openlegislation.uk/air-navigation-carbon-offsetting-and-reduction-scheme-for-international-aviation-order-2021/schedule-2/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.