第18條
The distance required by the aeroplane to land from a height of 50 feet does not at the aerodrome at which it is intended to land and at any alternate aerodrome exceed 70 per cent, or, if a visual approach and landing will be possible in the meteorological conditions forecast for the estimated time of landing, 80 per cent of the landing distance available on— (i) the most suitable runway for a landing in still air conditions; and (ii) the runway that may be required for landing because of the forecast wind conditions. (a) the landing weight; (b) the altitude at the aerodrome; (c) the temperature in the specified international standard atmosphere appropriate to the altitude at the aerodrome; (d) (i) a level surface in the case of runways usable in both directions; (ii) the average slope of the runway in the case of runways usable in only one direction; and (e) (i) still air conditions in the case of the most suitable runway for a landing in still air conditions; (ii) 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. The distance required to land from a height of 50 feet shall be taken to be that appropriate to—