Guidance concerning Air Navigation in and above the NAT MNPSA
Special non-compliance routings
Aircraft not equipped with two functioning Long Range Navigation Systems may only fly
through NAT MNPS Airspace via special designated routes. This is discussed in Chapter 1 at paragraph 1.4. Details of these special routes are contained in Chapter 11 at paragraph 11.2.2.
Aircraft not approved for MNPS/RVSM operations may climb and descend through NAT
MNPS/RVSM Airspace and in very limited, specified circumstances an MNPS Approved aircraft that is not Approved for RVSM operations may be granted permission to flight plan and operate through MNPS
Airspace at RVSM levels. (See Chapter 1 at 1.5 and 1.6).
Routings that may be flight planned and operated through NAT MNPS Airspace by aircraft
without functioning HF Communications equipment may be limited by the State of Registry of the operator or by the ATC Provider. This is discussed above in more detail at paragraph 4.2.12.
Lateral separation minima & resulting route definition conventions
In the North Atlantic MNPS Airspace the lateral separation standard is 60 NM.
60 NM is equivalent to one degree of latitude along any meridian and given that the vast majority of flights through this airspace are generally eastbound or westbound, this standard is deemed to be met by tracks
separated by one degree of latitude at common meridians.
Radar/ADS-B data is only available in very limited areas of the North Atlantic Region.
Therefore, ATC must depend upon aircraft supplied position reports for flight progress information. In order to provide separation assurance, ATC requires updates on the progress of flights at no more than hourly intervals. It has been determined that this criteria is met over a wide range of ground speeds if eastbound or westbound NAT flights report on passing each ten degrees of longitude. The criteria is also met by northbound or southbound flights reporting on passing each five degrees of latitude. In consequence, all flights which will generally route in an eastbound or westbound direction should normally be flight planned by specifying significant points at whole degrees of latitude at each crossed ten degrees of longitude (20°W, 30°W, 40°W etc.); and all generally northbound or southbound flights should normally be flight planned so that specified parallels of latitude spaced at five degree intervals (65°N, 60°N, 55°N etc.) are crossed at whole degrees of longitude. (N.B. North of 70°N the east/west distance between successive ten degree longitudes is less than 200 NM, or approximately 25 mins flight time. Consequently, eastbound/westbound NAT routings north of 70°N need only be defined by significant points at each twenty degrees of longitude
(i.e at 0°W, 20°W, 40°W, 60°W)).
OTS – Rationale, Structure, CDM & Track Message
As a result of passenger demand, time zone differences and airport noise restrictions, much
of the North Atlantic (NAT) air traffic contributes to two major alternating flows: a westbound flow departing Europe in the morning, and an eastbound flow departing North America in the evening. The effect of these flows is to concentrate most of the traffic unidirectionally, with peak westbound traffic crossing the 30W longitude between 1130 UTC and 1900 UTC and peak eastbound traffic crossing the 30W longitude
between 0100 UTC and 0800 UTC.
The NAT MNPS Airspace is consequently congested at peak hours and in order to provide
the best service to the bulk of the traffic, a system of organised tracks is constructed to accommodate as many flights as possible within the major flows, on or close to their minimum time tracks and altitude profiles. Due to the energetic nature of the NAT weather patterns, including the presence of jet streams,
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