Guidance concerning Air Navigation in and above the NAT MNPSA
provided to serviceability
satisfy anticipated traffic of transition area radars and
The impact on domestic route structures
navaids are checked before the system is finalised.
When the expected volume of traffic justifies it, tracks may be established to accommodate
the EUR/CAR traffic axis or traffic between the Iberian Peninsular and North America. Extra care is required when planning these routes as they differ slightly from the 'core tracks' in that they may cross each other (using vertical separations via different flight level allocations), and in some cases may not extend from coast-out to coast-in (necessitating random routing to join or leave). Similarly, some westbound tracks may commence at 30°W, North of 61°N, to accommodate NAT traffic routing via the Reykjavik OCA and
Collaborative Decision Making Process
Operators proposing to execute NAT crossings during the upcoming OTS period are
encouraged to contribute to the OTS planning process. A comprehensive set of Collaborative Decision
Making (CDM) procedures for NAT track design is now employed.
This CDM process commences with the Preferred Route Message (PRM) system, which has
been used in the NAT Region for many years. To enable oceanic planners to take into consideration operators' preferred routes in the construction of the OTS, all NAT operators (both scheduled and non- scheduled) are urged to provide information by AFTN message to the appropriate OACs regarding the optimum tracks of any/all of their flights which are intended to operate during the upcoming peak traffic periods. Such information should be provided, in the correct format, as far in advance as possible, but not later than 1900 UTC for the following day-time OTS and 1000 UTC for the following night-time OTS.
Addresses and formats for providing PRMs are published in the Canadian and UK AIPs/NOTAMs.
Subsequently, following the initial construction of the NAT tracks by the publishing
agencies (Gander OAC for Eastbound tracks and Shanwick OAC for Westbound tracks), the proposed tracks are published on an internet site for interested parties to view and discuss. One hour is allocated for each of the proposals during which any comments will be considered by the publishing agency and any changes which are agreed are then incorporated into the final track design. This internet site is currently operated by NAV CANADA. Access to this site is by password which any bona fide NAT operator may obtain on
application to NAV CANADA - see Canada AIP for details.
THE NAT TRACK MESSAGE
The agreed OTS is promulgated by means of the NAT Track Message via the AFTN to all
interested addressees. A typical time of publication of the day-time OTS is 2200 UTC and of the night-time
OTS is 1400 UTC.
This message gives full details of the co-ordinates of the organised tracks as well as the
flight levels that are expected to be in use on each track. In most cases there are also details of domestic entry and exit routings associated with individual tracks (e.g. ‘NERS…’ or ‘NAR …..’). In the westbound (day-time) system the track most northerly, at its point of origin, is designated Track 'A' (Alpha) and the next most northerly track is designated Track 'B' (Bravo) etc. In the eastbound (night-time) system the most southerly track, at its point of origin, is designated Track 'Z' (Zulu) and the next most southerly track is
designated Track 'Y' (Yankee), etc..
Examples of both eastbound and westbound systems and Track
Messages are shown below in this Chapter.
The originating OAC identifies each NAT Track Message, within the Remarks section
appended to the end of the NAT Track message, by means of a 3-digit Track Message Identification (TMI) number equivalent to the Julian calendar date on which that OTS is effective. For example, the OTS
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