Draft ICAO Circular on NLA.pdf - Airports Council International

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NLA. If inadequate, suitable strengthening measures, if economical and technically feasible, would need to
be implemented. Otherwise, alternate taxi routes should be established that would have suitably designed
underground structures where needed.
4.1.5.3.7 Possible mitigation measures for operation of a given NLA on taxiway bridges which do not
meet Annex 14, Volume I, code F specifications are:
a) where feasible, strengthen existing bridges;
b) provide a proven method of lateral restraint to prevent the aeroplane from veering off
the full bearing strength of the taxiway bridge; and
c) alternative path/bridge for RFF vehicles subject to its feasibility from an RFF point of
view.
4.1.6 Taxiway minimum separation distances
4.1.6.1 Runway to parallel taxiway separations
4.1.6.1.1 Annex 14, Volume I, paragraph 3.8.7, Table 3-1, columns 5 and 9 specify, for code F, a
minimum distance between the centre lines of a runway and the associated parallel taxiway of 190 m for
instrument runways and 115 m for non-instrument runways. It may be permissible to operate with lower
separation distances at an existing aerodrome if an aeronautical study indicates that such lower separation
distances would not adversely affect the safety or significantly effect the regularity of operations of
aeroplanes. See Note 2 to Table 3-1, and Notes 2, 3 and 4 to paragraph 3.8.7 of Annex14, Volume I.
4.1.6.1.2 Aerodrome Design Manual, Part 2: paragraph 1.2.19, Table 1-5 clarifies that the
runway/taxiway separation is based on the principle that the wing tip of an aeroplane taxiing on a parallel
taxiway should be clear of the runway strip.
The runway to taxiway separation distance = 1/2 wing span + 1/2 strip width.
For code E: 1/2 x 65 m + 1/2 x 300 m = 182.5 m
For code F: 1/2 x 80 m + 1/2 x 300 m = 190 m
4.1.6.1.3 Aerodrome Design Manual, Part 2 has related guidance in paragraph 1.2.46 to 1.2.49.
Furthermore, attention is drawn to the need to provide adequate clearance at an existing airport in order to
operate a new larger aeroplane with the minimum possible risk.
4.1.6.2 Hazard identification and analysis
4.1.6.2.1 The potential hazards associated with runway and parallel taxiway separation distances are:
a) collision risk between an aeroplane in flight and an object (fixed or mobile) on the
aerodrome;
<strong>ICAO</strong> Version 4.1 — 15 March 2004