Guidance concerning Air Navigation in and above the NAT MNPSA
effective on February 1st will be identified by TMI 032. (The Julian calendar date is a simple progression of numbered days without reference to months, with numbering starting from the first day of the year.) If any subsequent NAT Track amendments affecting the entry/exit points, route of flight (co-ordinates) or flight level allocation are made, the whole NAT Track Message will be re-issued. The reason for this amendment will be shown in the Notes and a successive alphabetic character, i.e. ‘A’, then ‘B’, etc., will be added to the end of the TMI number (e.g. TMI 032A).
The remarks section is an important element of the Track Message. The Remarks may vary
significantly from day to day. They include essential information that Shanwick or Gander need to bring to the attention of operators. These Remarks sometimes include details of special flight planning restrictions that may be in force and in the case of the Night-time Eastbound OTS Message, they include information on clearance delivery frequency assignments. The hours of validity of the two Organised Track Systems (OTS)
are normally as follows:
Day-time OTS Night-time OTS
1130 UTC to 1900 UTC at 30°W 0100 UTC to 0800 UTC at 30°W
Changes to these times can be negotiated between Gander and Shanwick OACs and the
specific hours of validity for each OTS are indicated in the NAT Track Message. For flight planning, operators should take account of the times as specified in the relevant NAT Track Message(s). Tactical extensions to OTS validity times can also be agreed between OACs when required, but these should
normally be transparent to operators.
Correct interpretation of the track message by airline dispatchers and aircrews is essential for
both economy of operation and in minimising the possibility of misunderstanding leading to the use of incorrect track co-ordinates. Oceanic airspace outside the published OTS is available, subject to application of the appropriate separation criteria and NOTAM restrictions. It is possible to flight plan to join or leave an outer track of the OTS. If an operator wishes to file partly or wholly outside the OTS, knowledge of separation criteria, the forecast upper wind situation and correct interpretation of the NAT Track Message will assist in judging the feasibility of the planned route. When the anticipated volume of traffic does not warrant publication of all available flight levels on a particular track, ATC will publish only those levels required to meet traffic demand. However, the fact that a specific flight level is not published for a particular track does not necessarily mean that it cannot be made available if requested.
OTS CHANGEOVER PERIODS
To ensure a smooth transition from night-time to day-time OTSs and vice-versa, a period of
several hours is interposed between the termination of one system and the commencement of the next. These periods are from 0801 UTC to 1129 UTC: and from 1901 UTC to 0059 UTC.
During the changeover periods some restrictions to flight planned routes and levels are
imposed. Eastbound and westbound aircraft operating during these periods should file flight level requests in accordance with the Flight Level Allocation Scheme (FLAS) as published in the UK and Canada AIPs
and shown at Attachment 6.
It should also be recognised that during these times there is often a need for clearances to be
individually co-ordinated between OACs and cleared flight levels may not be in accordance with those flight planned. If, for any reason, a flight is expected to be level critical, operators are recommended to contact the
initial OAC prior to filing of the flight plan to ascertain the likely availability of required flight levels.
NAT Doc 007