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taxilanes are implemented. For this, ICAO has specified separation distances for the different aircraft
categories and taxiway / taxilane situations. For code F, these minimum separation distances are based on
extrapolation of the distances given for code E. However, risk assessment, as well as operational
experience with code E aircraft, has shown that large aircraft can be operated safely on taxiways with
smaller separation distances than those given by ICAO.
AACG recommendations for minimum separation distances are based on these risk assessment and
operational experiences. The results of the taxiway deviation studies carried out by London-LHR, Frankfurt,
Amsterdam and Paris-CDG were used for these recommendations.
Different type of taxiway separation distances can be considered:
1. Parallel taxiways (Taxiway centre line to taxiway centre line)
2. Taxiway centre line to object
3. Aircraft stand taxilane to object
Parallel taxiways (Taxiway centre line to taxiway centre line)
In ICAO Annex 14, the minimum distance between two parallel taxiways is given as 97.5 meters for code F
aircraft. AACG recommend a distance of 91 meters if proper guidance, such as centre line lights or
equivalent guidance, is provided for night or low visibility operations.
Many alternate airports will have parallel taxiways, which are designed for code E aircraft. A separation
distance of 80 meters will in those cases normally be available. This does not mean that the A380 cannot
make use of one of the two parallel taxiways. If an A380 operates on one of the taxiways, the other taxiway
will be restricted for use by aircraft smaller than code E.
The ICAO requirement for parallel taxiways to be separated by 97.5m gives a margin of 17.5 meters when
two A380 aircraft taxi on parallel taxiways. The AACG recommends 91 meter, which results in a margin of
11m.
In case of an A380 operating at an alternate airport the occasion that two A380 aircraft will pass each other
on parallel taxiways is rare. However the maximum wingspan of the aircraft taxiing on the other taxiway in
the case an A380 taxies on parallel taxiways separated by only 80 meters can easily be calculated: taxiway
separation minus half wingspan of A380 minus margin equals half wingspan of the aircraft on the other
taxiway.
A study based on measurement with the real aircraft is conducted by several European States. Outputs are expected
by the middle of 2006. The ECAC NLA website is intended to reference those studies when available
draft
11
ICAO annex 14 requirements:
80 meters – 40 meters – 17.5 meters = 22.5 meters or a maximum wingspan of 45 meters (i.e. aircraft like
A310, A300 and B757).
AACG requirements:
80 meters – 40 meters – 11 meters = 29 meters or a maximum wingspan of 58 meters (i.e. aircraft like B767
and MD11).
Special attention must be given to curved taxiways or turning manoeuvres on taxiways. At all times a
minimum margin of 17.5 meters, or 11 meters if proper guidance is available, must be guaranteed. If this
minimum margin can-not be provided or the local authority does not feel comfortable with the actual margin
additional procedural separation must be provided.
Proposed alternative measures, operational procedures and operating restrictions for airports that
can-not comply with ICAO requirements or AACG recommendations related parallel taxiways
Restrict aircraft operations on the taxiway not used by the A380, to aircraft with a maximum wingspan of
45 meters.
If proper guidance is given, this restriction can be lifted to a maximum wingspan of 58 meters.
If necessary, procedural separation must be provided.
Publication in the appropriate aeronautical documentation is required.
Establish appropriate ATC operational procedures.
Taxiway centre line to object
For taxiway to object clearance, ICAO requires 57.5 meters while AACG recommend 49 meters if proper
guidance is available. However both accept lower separations distances for taxilanes based on the fact that
taxiing is more accurate on taxilanes. Although recent taxiway deviation studies have not found any relation
between taxi speed and deviations from the taxiway centre line, it is still one of the reasons why ICAO allows
smaller clearances on taxilanes. Extra caution on the more congested apron area could also be a factor in
better taxilane accuracy.
The local authority could allow taxilane to object clearances on taxiways, if necessary with measures such
as taxi speed reduction. If these measures can be ensured on the taxiway, e.g. by “follow me” guidance
and/or clear publication in the aeronautical documents, it may be acceptable to taxi an A380 on taxiways
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