# The Air Navigation (General) Regulations 2005, Paragraph 6: Weight and performance of public transport aeroplanes designated as aeroplanes of performance group X


For the purposes of article 44(6), an aeroplane in respect of which there is in force under article 44(5) a permission designating the aeroplane as being of performance group X shall not fly for the purpose of public transport unless the weight of the aeroplane at the commencement of the take-off run is such that the following requirements are satisfied—
(1) That weight shall not exceed the maximum take-off weight specified for the altitude at the aerodrome at which the take-off is to be made, or for the altitude and the air temperature at such aerodrome, as the case may be.
(2) The minimum effective take-off runway length required, specified as being appropriate to—
(a) the weight of the aeroplane at the commencement of the take-off run;
(b) the altitude at the aerodrome;
(c) the air temperature at the time of take-off;
(d) the condition of the surface of the runway from which the take-off will be made;
(e) the overall slope of the take-off run available; and
(f) not more than 50 per cent. of the reported wind component opposite to the direction of take-off or not less than 150 per cent. of the reported wind component in the direction of take-off,
shall not exceed the take-off run available at the aerodrome at which the take-off is to be made.
(3) Subject to sub-paragraphs (4) and (5) the take-off flight path with one power unit inoperative, specified as being appropriate to—
(a) the weight of the aeroplane at the commencement of the take-off run;
(b) the altitude at the aerodrome; and
(c) not more than 50 per cent. of the reported wind component opposite to the direction of take-off or not less than 150 per cent. of the reported wind component in the direction of take-off, and plotted from a point 50 feet above the end of the minimum effective take-off runway length required at the aerodrome at which the take-off is to be made,
shall show that the aeroplane will clear any obstacle in its path by a vertical interval of not less than the greater of 50 feet or 35 feet plus one-hundredth of the distance from the point on the ground below the intended line of flight of the aeroplane nearest to the obstacle to the end of the take-off distance available, measured along the intended line of flight of the aeroplane.
(4) For the purpose of sub-paragraph (3) an obstacle shall be deemed to be in the path of the aeroplane if the distance from the obstacle to the nearest point on the ground below the intended line of flight does not exceed—
(a) a distance of 60 metres plus half the wing span of the aeroplane plus one-eighth of the distance from such point to the end of the take-off distance available measured along the intended line of flight; or
(b) 900 metres,
whichever is the less.
(5) In assessing the ability of the aeroplane to satisfy sub-paragraph (3), in so far as it relates to flight path, it shall not be assumed to make a change of direction of a radius less than the radius of steady turn corresponding to an angle of bank of 15°.
(6) Subject to sub-paragraph (8), and in the circumstances mentioned in sub-paragraph (7), the weight of the aeroplane shall be such that the aeroplane will be capable of a rate of climb of at least K(Vso/100)2 feet per minute at an altitude not less than the minimum altitude for safe flight stated in or calculated from the information contained in the operations manual relating to the aeroplane, where Vso is in knots and K has the value of 797–1060/N, N being the number of power units installed.
(7) The circumstances mentioned in sub-paragraph (6) are:
(a) at any point on the route or any planned diversion from the route, having regard to the fuel and oil expected to be consumed up to that point; and
(b) with one power unit inoperative and the other power unit or units operating within the maximum continuous power conditions specified.
(8) As an alternative to sub-paragraph (6), but subject to sub-paragraph (9), the aeroplane may be flown at an altitude from which, in the event of failure of one power unit, it is capable of reaching an aerodrome where a landing can be made in accordance with sub-paragraph (14), relating to an alternate aerodrome. In that case the weight of the aeroplane shall be such that, with the remaining power unit or units operating within the maximum continuous power conditions specified, it is capable of maintaining a minimum altitude on the route to such aerodrome of 2,000 feet above all obstacles within 10 nautical miles on either side of the intended track.
(9) If the operator of the aeroplane is satisfied, taking into account the navigation aids which can be made use of by the aeroplane on the route, that the commander of the aeroplane will be able to maintain his intended track on that route within a margin of 5 nautical miles, sub-paragraph (8) shall have effect as if 5 nautical miles were substituted for 10 nautical miles and sub-paragraph (10) shall apply.
(10) In the circumstances referred to in sub-paragraph (9):
(a) the rate of climb, specified for the appropriate weight and altitude, used in calculating the flight path shall be reduced by an amount equal to K(Vso/100)2 feet per minute;
(b) the aeroplane shall comply with the climb requirements of sub-paragraph (6) at 1,000 feet above the chosen aerodrome;
(c) account shall be taken of the effect of wind and temperature on the flight path; and
(d) the weight of the aeroplane may be assumed to be progressively reduced by normal consumption of fuel and oil.
(11) Subject to sub-paragraph (12), if:
(a) any two power units of an aeroplane having four power units shall become inoperative at any point along the route or along any planned diversion from the route; and
(b) that point is more than 90 minutes flying time (assuming all power units were to be operating) from the nearest aerodrome at which a landing can be made in compliance with sub-paragraph (14), relating to an alternate aerodrome,
the aeroplane shall be capable of continuing the flight at an altitude of not less than 1,000 feet above ground level to a point above that aerodrome.
(12) In assessing the ability of the aeroplane to satisfy sub-paragraph (11) it shall be assumed that the remaining, operative power units will operate within the specified maximum continuous power conditions, and account shall be taken of the temperature and wind conditions expected for the flight.
(13) The landing weight of the aeroplane shall not exceed the maximum landing weight specified for the altitude at the aerodrome at which it is intended to land and at any alternate aerodrome.
(14) Subject to sub-paragraph (15), the required landing runway lengths, respectively specified as being appropriate to the aerodrome of intended destination and the alternate aerodrome, shall not exceed the landing distance available on—
(a) the most suitable runway for landing in still air conditions; and
(b) the runway that may be required for landing because of the forecast wind conditions,
at the aerodrome at which it is intended to land or at any alternate aerodrome, as the case may be.
(15) For the purpose of sub-paragraph (14) the required landing runway lengths shall be taken to be those specified as being appropriate to—
(a) the landing weight;
(b) the altitude at the aerodrome;
(c) still air conditions in the case of the most suitable runway for a landing in still air conditions; and
(d) not more than 50 per cent. of the forecast wind component opposite to the direction of landing or not less than 150 per cent. of the forecast wind component in the direction of landing in the case of the runway that may be required for landing because of the forecast wind conditions.

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Source: https://www.legislation.gov.uk/uksi/2005/1980/schedule/2/paragraph/6 (the official version)
Page: https://openlegislation.uk/air-navigation-general-regulations-2005/schedule-2/paragraph-6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.