# The Air Navigation (Carbon Offsetting and Reduction Scheme for International Aviation) Order 2021, Paragraph 5: Block-off/Block-on

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

The aeroplane operator must use the following formula to compute fuel use according to the Block-off/Block-on Method—
F N = T N − R N where—
FN = Fuel used for the flight under consideration (i.e. flight N) determined using Block-off/Block-on Method (in tonnes);
TN = Amount of fuel contained in aeroplane tanks at Block-off for the flight under consideration i.e. flight N (in tonnes); and
RN = Amount of fuel remaining in aeroplane tanks at Block-on of the flight under consideration i.e. flight N (in tonnes).

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Source: https://www.legislation.gov.uk/uksi/2021/534/schedule/2/paragraph/5 (the official version)
Page: https://openlegislation.uk/air-navigation-carbon-offsetting-and-reduction-scheme-for-international-aviation-order-2021/schedule-2/paragraph-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.