(1) This article makes provision about the meaning of expressions used in the definition of “flight restriction zone” in article 94A that applies in relation to a protected aerodrome which is-
(a) an EASA certified aerodrome,
(b) a Government aerodrome, or
(c) a national licensed aerodrome,
and which has an aerodrome traffic zone.
(2) Subject to paragraph (4), there is one runway protection zone for each runway threshold of each runway at the aerodrome.
(3) A “runway protection zone”, in relation to a runway threshold at the aerodrome, is the airspace extending from the surface to a height of 2,000 feet above the level of the aerodrome within the area bounded by a rectangle-
(a) whose longer sides measure 5 km;
(b) whose shorter sides measure-
(i) 1 km (except in the case of Heathrow Airport);
(ii) 1.5 km, in the case of Heathrow Airport; and
(c) which is positioned so that-
(i) one of the shorter sides of the rectangle (“side A”) runs across the runway threshold, and
(ii) the two longer sides of the rectangle are parallel to, and equidistant from, the extended runway centre line as it extends from side A out to, and beyond, the runway end to which the runway threshold relates.
(4) There is no runway protection zone-
(a) for any runway threshold at the London Heliport;
(b) for any runway threshold that is prescribed, or of a description prescribed, for the purposes of this paragraph.
(5) The “runway threshold” of a runway at the aerodrome is the location that, for the purpose of demarcating the start of the portion of the runway that is useable for landing, is-
(a) notified as the threshold of the runway, or
(b) set out as the threshold of the runway in the UK military AIP.
(6) The “extended runway centre line”, in relation to a runway at the aerodrome, is an imaginary straight line which runs for the length of the runway along its centre and then extends beyond both ends of the runway.
(7) An “additional boundary zone” is the airspace extending from the surface to a height of 2,000 feet above the level of the aerodrome within any part of the area between-
(a) the boundary of the aerodrome, and
(b) a line that is 1 km from the boundary of the aerodrome (the “1 km line”),
that is neither within the aerodrome traffic zone nor within any runway protection zone at the aerodrome.
(8) The 1 km line is to be drawn so that the area which is bounded by it includes every location that is 1 km from the boundary of the aerodrome, measured in any direction from any point on the boundary.