North Atlantic (NAT)
International Operations Regional
Figure: NAT Region, from Eddie's notes.
North Atlantic Requirement
ICAO Doc 7030, §NAT, ¶3.4.1] Within the NAT Region, aircraft equipped for SATCOM voice shall restrict the use of such equipment to emergencies and non-routine situations. An unforeseen inability to communicate by voice radio constitutes a non-routine situation. Since oceanic traffic typically communicates through aeradio facilities, a SATCOM call due to an unforeseen inability to communicate by other means should be made to such a facility rather than the ATC centre unless the urgency of the communication dictates otherwise. Dedicated SATCOM telephone numbers (short codes) for aeradio facilities and air traffic control facilities are published in national AIPs.
HF is required for U.S. Operators for just about every oceanic region in the world, though SATCOM can be used. The North Atlantic places this additional restriction on the use of SATCOM in place of HF for position reports.
More about this: HF.
This region is moving from a mix of navigation requirements to the system of Performance Based Navigation outlined in ICAO Document 9613. Current navigation requirements are available on Jeppesen Airway Manual Air Traffic Control pages and Chapter 4 of each region covered by ICAO Document 7030.
RNAV 10 (RNP 10)
[ICAO Doc 7030 Amendment 1, §NAT, ¶184.108.40.206.]
- A lateral separation minimum of 93 km (50 NM) may be applied between flights operating within the control area of the New York Oceanic FIR.
- The aircraft and operator must be approved RNP 10 or RNP 4 by the State of the Operator or the State of Registry, as appropriate. RNP 10 is the minimum navigation specification for the application of 93 km (50 NM) lateral separation.
More about this:Required Navigation Performance-10 (RNP-10).
Keep in mind RNP 10 is an exception to the rule of Required Navigation Performance standards, "RNAV 10" retains the "RNP 10" designation for matters of convenience.
Minimum Navigation Performance Specifications (MNPS)
[ICAO Doc 7030 Amendment 1, §NAT, ¶220.127.116.11.1.]
- The MNPS shall be applicable in that volume of airspace between FL 285 and FL 420 within the Oceanic Control Areas of Santa Maria, Shanwick, Reykjavik, Gander Oceanic and New York Oceanic, excluding the area west of 60°W and south of 38°30′N.
- For flights within the volume of airspace specified in 18.104.22.168.1.1 aircraft shall have lateral navigation performance capability such that:
- the standard deviation of lateral track errors shall be less than 11.7 km (6.3 NM);
- the proportion of the total flight time spent by aircraft 56 km (30 NM) or more off the cleared track shall be less than 5.3 × 10-4; and
- the proportion of the total flight time spent by aircraft between 93 and 130 km (50 and 70 NM) off the cleared track shall be less than 1.3 × 10-5.
The MNPS has been replaced by the North Atlantic High Level Airspace (NAT HLA) but ICAO Doc 7030 hasn't caught up yet. For now, you can just associate NAT HLA with MNPS.
More about this: North Atlantic Airspace (NAT HLA).
All three countries listed in the NAT region, the Azores, Greenland, and Iceland are listed as WGS-84 in the Jeppesen WGS-84 website, but Greenland is listed only as partially compliant in their Jeppesen Airway Manual ATC page, dated 16 Aug 2013.
More about this: World Geodetic System 84 (WGS-84).
[ICAO Doc 7030 Amendment 1, §NAT, ¶4.2.1.] RVSM shall be applicable in that volume of airspace between FL 290 and FL 410 inclusive in all FIRs of the NAT Region.
More about this: Reduced Vertical Separation Minimum (RVSM).
Transition altitude and level procedures vary by country.
More about this: Transition Altitude / Layer / Level.
North American Routes (NARs)
[NAT Doc 007, ¶3.3.1] The North American Routes (NARs) consist of a numbered series of predetermined routes which provide an interface between NAT oceanic and North American domestic airspace. The NAR System is designed to accommodate major airports in North America.
The NARs used to be in an easy to find location in paper copies of Jeppesen Airway manuals but not so much with the electronic version. The link provided by NAT Doc 007 died years ago. The FAA Order (7430.2A) that established them way back in 1984 was canceled in 2014. You can find a listing of the NARS in the JeppView North Atlantic En Route pages. (If you are flying a PlaneView cockpit, you will also seem them displayed if you select high altitude routes.)
North Atlantic European Routing Scheme (NERS)
[NAT Doc 007, ¶3.3.8] The NERS exists to provide an interface between NAT oceanic and European domestic airspace. The scheme is similar in concept to the NARS which has been in use in North America by NAT traffic for many years. It consists of a numbered series of predetermined routes, designed to accommodate eastbound traffic exiting the NAT en route to a number of major European airports.
Organized Track System (OTS)
[NAT Doc 007, ¶2.1.1.] 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.
[NAT Doc 007, ¶2.1.2.] Due to the constraints of large horizontal separation criteria and a limited economical height band (FL310–400) the airspace is congested at peak hours. 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, consecutive eastbound and westbound minimum time tracks are seldom identical. The creation of a different organised track system is therefore necessary for each of the major flows. Separate organised track structures are published each day for eastbound and westbound flows. These track structures are referred to as the Organised Track System or OTS.
[NAT Doc 007, ¶2.1.4.] Over the high seas, the NAT Region is primarily Class A airspace (at and above FL55) (See ICAO Doc. 7030 - NAT Regional Supplementary Procedures), in which Instrument Flight Rules (IFR) apply at all times. Throughout the NAT Region, below FL410, 1000 feet vertical separation is applied. However, airspace utilisation is under continual review, and within the MNPS portion of NAT airspace, in addition to the strategic and tactical use of 'opposite direction' flight levels during peak flow periods the Mach Number Technique is applied.
[NAT Doc 007, ¶2.3.1.] The agreed OTS is promulgated by means of t h e 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.
[NAT Doc 007, ¶2.3.5.] The hours of validity of the two Organised Track Systems (OTS) are normally as follows:
- Day-time OTS 1130 UTC to 1900 UTC at 30°W
- Night-time OTS 0100 UTC to 0800 UTC at 30°W
Each country departs in some ways with the ICAO standard and common US practices. Pilots should always refer to the Jeppesen Airway Manual, Air Traffic Control, State Rules and Procedures pages for each country on their itineraries for differences with ICAO Standards, Recommended Practices and Procedures. More about this: US versus ICAO.
The following are a sampling of some of the differences, there are many more. You should check the Jeppesen Airway Manual State pages for every country you takeoff, overfly, or land.
[NAT Doc 007, ¶22.214.171.124.] Unable to obtain oceanic clearance using HF voice.
- Aircraft operating outside VHF coverage that are unable to contact ATC on HF to obtain an Oceanic clearance shall continue to operate at the last assigned flight level and along the cleared route of flight until communications are re-established.
Note.— Failure of HF communications often stems from poor signal propagation, frequently because of sun spot activity, and is likely to simultaneously affect multiple aircraft operating in a particular region. ATM systems dependent on HF are designed around the assumption that communication may be temporarily interrupted and that aircraft affected will continue to operate in accordance with the last received and acknowledged clearance, until communication is restored.
[NAT Doc 007, ¶9.3]
- The pilot shall attempt to contact either another aircraft or any ATC facility and inform it of the difficulty and request that information be relayed to the ATC facility with whom communications are intended.
- If operating with a received and acknowledged oceanic clearance, the pilot shall enter oceanic airspace at the cleared oceanic entry point, level and speed and proceed in accordance with the received and acknowledged oceanic clearance. Any level or speed changes required to comply with the oceanic clearance shall be completed within the vicinity of the oceanic entry point.
- If operating without a received and acknowledged oceanic clearance, the pilot shall enter oceanic airspace at the first oceanic entry point, level and speed, as contained in the filed flight plan, and proceed via the filed flight plan route to landfall. That first oceanic level and speed shall be maintained to landfall.
- The pilot shall proceed in accordance with the last received and acknowledged oceanic clearance, including level and speed, to the last specified oceanic route point, normally landfall, and then continue on the filed flight plan route. The pilot shall maintain the last assigned oceanic level and speed to landfall and, after passing the last specified oceanic route point, shall conform with the relevant State procedures/regulations.
- The pilot shall proceed in accordance with the last received and acknowledged oceanic clearance, including level and speed, to the last specified oceanic route point, normally landfall. After passing this point, the pilot shall conform with the relevant State procedures/regulations and rejoin the filed flight plan route by proceeding, via the published ATS route structure where possible, to the next significant point ahead as contained in the filed flight plan.
Communications failure prior to entering NAT Region
Communications failure prior to exiting NAT Region – Cleared on filed flight plan route
Communications failure prior to exiting NAT Region – Cleared on other than filed flight plan route
Note.— The relevant State procedures/regulations to be followed by aircraft in order to rejoin its filed flight plan route are specified in detail in the appropriate national Aeronautical Information Publication.
These are exceptions to ICAO Lost Comm procedures.
More about this: Lost Communications.
Strategic Lateral Offset Procedure (SLOP)
[NAT Doc 007, ¶8.5.2.] This [SLOP] procedure provides for offsets within the following guidelines:
- along a route or track there will be three positions that an aircraft may fly: centreline or one or two miles right;
- offsets will not exceed 2 NM right of centreline; and
- offsets left of centreline must not be made.
[Jeppesen Airway Manual, Air Traffic Control, State Rules and Procedures, Europe, Iceland, 16 Aug 2013] SLOP is not allowed in airspace where the applied lateral separation is less than 30 NM. /since the lateral separation may be as low as 7 NM below FL285 in the Reykjavik CTA the following applies:
- Aircraft shall not apply SLOP below FL285 in the Reykjavik CTA. Aircraft shall maintain the centre line of the cleared track.
SLOP is encourage in the North Atlantic except for the Iceland restriction noted.
More about this: Strategic Lateral Offset Procedure (SLOP).
ICAO Doc 7030 - Regional Supplementary Procedures, International Civil Aviation Organization, 2 2008
ICAO Doc 9613 - Performance Based Navigation (PBN) Manual, International Civil Aviation Organization, 2008
NAT Doc 007, North Atlantic Operations and Airspace Manual Doc 007, Edition 2013
Jeppesen Airway Manual