# The Civil Aviation (Route Charges for Navigation Services) Regulations 1994, Regulation 6: Calculation of the Charge


(1) Except in the case of flights specified in regulation 7 of these Regulations, the charge shall be calculated in ECUs according to the following formula—
r=N×U where
r is the charge for the flight, N is the number of service units relating to that flight and U is the appropriate unit rate specified in column 3 of Schedule 2 hereto in relation to the specified airspace through which the flight is made, increased or decreased as the case may be by the same percentage as the relevant national currency has increased or decreased against the ECU as compared with the rate of exchange specified in column 4 of the said Schedule in relation to that airspace.
(2) For the purpose of the preceding paragraph, the number of service units relating to a flight shall be calculated in accordance with the following formula—
N=d×p where
d is the distance factor for the flight in the specified airspace in question and p is the weight factor for the aircraft concerned.
(3) For the purposes of the preceding paragraph—
(a) the distance factor shall be the number of kilometres in the great circle distance between the points specified in paragraph (4) of this regulation minus 20 kilometres for each landing and take-off in the specified airspace in question, divided by 100 and expressed to two places of decimals, and
(b) the weight factor, subject to the provisions of paragraph (6) of this regulation, shall be equal to the square root of the quotient obtained by dividing by 50 the number of metric tonnes of the maximum total weight authorised of the aircraft and shall be expressed to two places of decimals.
(4) The points referred to in paragraph (3) of this regulation are—
(a) the aerodrome of departure within the specified airspace in question or, if there is no such aerodrome, the point specified in paragraph (5) of this regulation as the standard point of entry into that airspace for the route in question or, in the cas e specified in the proviso to that paragraph, the actual point of entry into that airspace; and
(b) the aerodrome of first destination within the specified airspace in question or, if there is no such aerodrome, the point specified in paragraph (5) of this regulation as the standard point of exit from that airspace for the route in question or, in the case specified in the proviso to that paragraph, the actual point of exit from that airspace.
(5) The standard points of entry and exit referred to in paragraph (4) of this regulation are the points, as described in the United Kingdom Air Pilot or relevant AIP as the case may be, where the median line of the appropriate airway or upper Air Traffic Service route so described crosses the boundary of the airspace in question.
For the purposes of this paragraph, the appropriate airway or route, in the case of a flight made between 1st January and 31st December in any year, shall be—
(a) the airway or route between the aerodrome of departure and the aerodrome of first destination which appears to Eurocontrol on 1st January of that year to be the most frequently used such airway or route; or
(b) if Eurocontrol is unable to ascertain on 1st January of that year which such airway or route is the most frequently used, the shortest such airway or route;
Provided that in the case of a flight in respect of which the aerodrome of departure or the aerodrome of first destination is situated in one of the zones specified in column 1 of Schedule 3 to these Regulations but that aerodrome is not specified in column 2 of the said Schedule the point of entry into or, as the case may be, of exit from the said airspace shall be the actual point where the flight in question crosses the lateral limits of that airspace as described in the United Kingdom Air Pilot or relevant AIP as the case may be.
(6) The weight factor for an aircraft of any type shall be calculated by reference to the maximum total weight authorised of the heaviest aircraft of that type:
Provided that where an operator has indicated to Eurocontrol, within the period of one year immediately preceding the flight, the composition of the fleet of aircraft which he operates and which includes two or more aircraft which are different versions of the same type of aircraft, the weight factor shall be calculated by reference to the average of the maximum total weight authorised of all his aircraft of that type so indicated to Eurocontrol.

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Source: https://www.legislation.gov.uk/uksi/1994/3071/regulation/6 (the official version)
Page: https://openlegislation.uk/civil-aviation-route-charges-for-navigation-services-regulations-1994/regulation-6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.