# The Air Navigation (Carbon Offsetting and Reduction Scheme for International Aviation) Order 2021, Paragraph 3: Method A

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

(1) The aeroplane operator must use the following formula to compute fuel use according to Method A—
F N = T N − T N±1 ± U N±1 where—
FN = Fuel used for the flight under consideration (i.e. flight N) determined using Method A (in tonnes);
TN = Amount of fuel contained in aeroplane tanks once fuel uplifts for the flight under consideration (i.e. flight N) are complete (in tonnes);
TN+1 = Amount of fuel contained in aeroplane tanks once fuel uplifts for the subsequent flight (i.e. flight N+1) are complete (in tonnes); and
UN+1 = Sum of fuel uplifts for the subsequent flight (i.e. flight N+1) 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 no fuel uplift for the flight or subsequent flight takes place, the amount of fuel contained in aeroplane tanks (TN or TN+1) must be determined at block-off for the flight or subsequent flight. In exceptional cases the variable TN+1 cannot be determined. This is the case when an aeroplane performs activities other than a flight, including undergoing major maintenance involving the emptying of the tanks, after the flight to be monitored. In such case the aeroplane operator may substitute the quantity “TN+1 + UN+1” with the amount of fuel remaining in tanks at the start of the subsequent activity of the aeroplane or fuel in tanks at Block-on, as recorded by technical logs.

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Source: https://www.legislation.gov.uk/uksi/2021/534/schedule/2/paragraph/3 (the official version)
Page: https://openlegislation.uk/air-navigation-carbon-offsetting-and-reduction-scheme-for-international-aviation-order-2021/schedule-2/paragraph-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.