Regulation 12 Weight and performance of public transport aeroplanes classified as aeroplanes of performance group X in their certificates of airworthiness

the weight of the aeroplane at the commencement of the take off run;

the altitude at the aerodrome;

the air temperature at the time of take off;

the condition of the surface of the runway from which the take off will be made;

the overall slope of the take off run available; and

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, does not exceed the take off run available at the aerodrome at which the take off is to be made.

The take off flight path with one power unit inoperative, specified as being appropriate to—

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, shows that the aeroplane will thereafter 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.

For the purpose of sub-paragraph (i) 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—

whichever is the less.

In assessing the ability of the aeroplane to satisfy this condition, 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°.

Subject to sub-paragraph (ii), the weight of the aeroplane at any point on the route or any planned diversion therefrom, having regard to the fuel and oil expected to be consumed up to that point, shall be such that the aeroplane, with one power unit inoperative and the other power unit or units operating within the maximum continuous power conditions specified, 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.

As an alternative to sub-paragraph (i), 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 (b) of condition (3) 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:

• Provided that where 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, the foregoing provisions of this sub-paragraph shall have effect as if 5 nautical miles were substituted therein for 10 nautical miles and

  1. (aa)

     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;

  2. (bb)

     the aeroplane shall comply with the climb requirements of sub-paragraph (a)(i) of condition (2) at 1,000 feet above the chosen aerodrome;

  3. (cc)

     account shall be taken of the effect of wind and temperature on the flight path; and

  4. (dd)

     the weight of the aeroplane may be assumed to be progressively reduced by normal consumption of fuel and oil.

the most suitable runway for landing in still air conditions; and

the runway that may be required for landing because of the forecast wind conditions,

the landing weight;

the altitude at the aerodrome;

still air conditions in the case of the most suitable runway for a landing in still air conditions; and

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.