Draft ICAO Circular on NLA.pdf - Airports Council International

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4.1.6.3.3 As such, the following options may be considered:
3 Additional guidance material on minimum separation distances will be included in the revised Aerodrome Design Manual, Part 2
(4th edition)
a) place a restriction on the wing span of aircraft using the parallel taxiway if continued
unrestricted runway operation is desired;
b) conduct a local study for any impact on ILS signal; and
c) in deciding whether to approve unrestricted operations, consider the expected frequency
of potentially limiting NLA operations.
4.1.6.3.4 The minimum distance between the centre lines of a runway and a parallel taxiway may need
to be increased beyond those specified in Annex 14, Volume I, Table 3-1, taking into account the location
of the holding position, the length of the most demanding aircraft at the holding position, and the minimum
distance (as per Table 3-1, column 11) needed for an aircraft to taxi behind it safely 3 .
4.1.6.3.5 In some complex aerodrome layouts, a specific study may be needed to evaluate the
situations where existing taxiways are permitted to be used by a code F aeroplane.
4.1.6.3.6 A review of present taxi operation procedures and guidance technologies may be needed.
Mitigation measures may require some surface movement restrictions, alternative operational procedures or
additional guidance systems.
4.1.6.3.7 In addition, Annex 14, Volume I, section 2.9 advises effective control of runway surface
friction characteristics, reliable wind reporting, and where applicable, reporting of runway surface friction
characteristics. Aircraft operators could apply operational restrictions according to conditions.
ILS signal interference by a taxiing or stationary aircraft
4.1.6.3.8 ILS signal distortion risk should be assessed on a case-by-case study basis taking into
account specific aerodrome layout and traffic density. Individual case studies could benefit from several
ongoing generic studies dealing with current code E and expected code F aircraft geometry effects on ILS
safety area.
4.1.6.4 Parallel taxiway separation
4.1.6.4.1 Annex 14, Volume I, paragraph 3.8.7, Table 3-1, column 10 specifies the minimum distance
between the centre lines of two parallel taxiways should be 97.5 m where the code letter is F. 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.
4.1.6.4.2 Aerodrome Design Manual, Part 2, paragraph 1.2.13 to 1.2.15, Table 1-1 and 1-4, Figure 1-4
clarifies that this minimum separation distance is equal to the wing span plus max lateral deviation plus
increment.
<strong>ICAO</strong> Version 4.1 — 15 March 2004