Draft ICAO Circular on NLA.pdf - Airports Council International

<strong>ICAO</strong> Version 4.1 — 15 March 2004
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Note.— Special attention should be given to the offset of centre line lights in relation to
centre line markings. Especially during winter conditions distinction between markings and offset lights
could be difficult.
4.1.6.9 Aprons — Clearance distances on aircraft stands
4.1.6.9.1 Annex 14, Volume I, paragraph 3.12.6 recommends that the minimum distance between the
aeroplane and an obstacle should be at least 7.5 m except in the following special circumstances at a nose-in
stand, this may be reduced:
a) between terminal (including fixed passenger boarding bridge) and aircraft nose; and
b) over any portion of stand provided with azimuth guidance by a visual docking guidance
system.
4.1.6.10 Hazard identification and analysis
4.1.6.10.1 The existing aprons on most of today's airports were not designed with code F aircraft in
mind. Consequently, the safety margins tend to get reduced when used by such larger aeroplanes.
4.1.6.10.2 The causes of a collision between aeroplane and obstacle on apron or holding bay could be
classified as:
a) mechanical failure (hydraulic system, brake, nose gear steering);
b) surface conditions (standing water, ice-covered surface, friction coefficient);
c) loss of visual taxi guidance system (docking system out of service,...); and
d) human factors (directional control, orientation error, …).
4.1.6.10.3 Consequences of collision on apron or holding bay are potentially major.
4.1.6.11 Risk assessment and possible mitigation measures
4.1.6.11.1 Collision hazard during taxiing depends more on human factors than on aeroplane
performance (all functioning aeroplanes respond reliably to pilot directional inputs when taxiing at ordinary
speeds) . Therefore, the expected NLA behaviour could be inferred in part from existing aircraft behaviour.
Nevertheless, caution should be exercised with regard to the implications of significantly increased wingspan
of NLAs.
4.1.6.11.2 Reduced separation at the gate is possible where azimuth guidance by a visual docking
guidance system is provided.
4.1.6.11.3 Some operational restrictions may be required. Adequate clearances behind parked or
holding aeroplanes will be required, noting the increased length of code F, and some new longer code E
aircraft.