NAT HLA

Airspace

Eddie sez:

All of us who fly the North Atlantic for a living are in a continuing battle to keep up with the changing requirements. In 2019, the North Atlantic System Planning Group (NAT SPG) announced that they would take a break for the six or seven changes every year and promised to have a change free 2020. There were changes, but most of those changes were a relaxing of standards due to the worldwide decrease in air traffic that year. I'll outline the state of affairs as of the close of 2019, assuming that is where we will end up once traffic ramps back up in 2021.

The NAT SPG does an excellent job of publishing the rules of the airspace in ICAO Nat Doc 007, their airspace manual. The problem is that it is 177 pages and there are a lot of ops bulletins out there to keep track of.

I think the easiest way to keep abreast of life in the North Atlantic High Level Airspace (NAT HLA) is to subscribe to Ops.Group. Nobody does a better job of keeping this complicated airspace understandable. They approach this from the standpoint of "What I've got" versus "What I don't have" and translate that to "Where can I go?" I think that works very well, so I'll copy them and add specific references.

images

Photo: NAT HLA, NAT Doc 007, figure 1.
Click photo for a larger image

Everything here is from the references shown below, with a few comments in an alternate color.

Last revision:

2020-12-12


What I've got: Everything

What I don't have: RVSM

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] You can't cruise at levels between FL290 - FL410 inclusive in the NAT region.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] You can fly at FL280 westbound, FL270 eastbound, or FL430 in either direction. If you are HLA approved: You can climb and descend through HLA RVSM airspace to reach your non-RVSM level, and ATC may approve you to fly within RVSM airspace, if you 1. Are a delivery flight, or 2. Did have RVSM approval but returning for repairs, or 3. Humanitarian. Contact the first Oceanic Centre by phone about 6 hours before you plan to enter.

Why . . .

[NAT Doc 007, ¶1.6]

To Climb/Descend Through RVSM Levels: 1.6.1 NAT HLA approved aircraft that are not approved for RVSM operation will be permitted, subject to traffic, to climb/descend through RVSM levels in order to attain cruising levels above or below RVSM airspace. Flights should climb/descend continuously through the RVSM levels without stopping at any intermediate level and should “Report leaving” current level and “Report reaching” cleared level (N.B. this provision contrasts with the regulations applicable for RVSM airspace operations in Europe, where aircraft not approved for RVSM operations are not permitted to effect such climbs or descents through RVSM levels.). Such aircraft are also permitted to flight plan and operate at FL430 either Eastbound or Westbound above the NAT HLA.

To Operate at RVSM Levels: 1.6.2 ATC may provide special approval for a NAT HLA approved aircraft that is not approved for RVSM operation to fly in the NAT HLA provided that the aircraft:

a) is on a delivery flight; or

b) was RVSM approved but has suffered an equipment failure and is being returned to its base for repair and/or re-approval; or

c) is on a mercy or humanitarian flight.

More About this . . .

Reduced Vertical Separation Minimum (RVSM).

What I don't have: HLA approval

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] You can't fly in NAT HLA airspace, which is from FL285 - FL420.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] Going around HLA isn’t really feasible, because it extends from about 20N to the North Pole. You can fly in the NAT region at FL280 westbound, FL270 eastbound, or FL430 in either direction

Why . . .

[NAT Doc 007, ¶1.1.1] NAT HLA is that volume of airspace between flight level (FL) 285 and FL 420 within the oceanic control areas of Bodo Oceanic, Gander Oceanic, New York Oceanic East, Reykjavik, Santa Maria and Shanwick, excluding the Shannon and Brest Ocean Transition Areas.

[NAT Doc 007, ¶1.2.1] All flights within the NAT HLA must have the approval of either the State of Registry of the aircraft, or the State of the operator.

More About this . . .

Summary of Requirements.

What I don't have: CPDLC

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] You can’t operate FL 290 - FL410 anywhere in the NAT HLA.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] You can cruise at FL 280 or below, or FL 410 or above anywhere in the HLA, including the tracks. There are exempted areas, where you’re all good: North of 80N, Surveillance airspace (where ATC can see you on radar or ADS-B), the Tango Routes, and New York Oceanic East. If you have ADS-B and VHF, Gander will accept you on a line RATSU 61N20W 63N30W 62N40W 61N50W SAVRY or north of.

Why . . .

[NAT Doc 007, ¶1.8.1] The NAT Data Link Mandate (DLM) requires aircraft to be equipped with, and operating, CPDLC and ADS-C in the NAT region. Currently, the mandate incorporates FL290 to FL410 inclusive.

[NAT Doc 007, ¶1.8.2] The DLM is not applicable to aircraft operating in:

  • Airspace north of 80° North;
  • New York Oceanic East flight information region (FIR);
  • Airspace where an ATS surveillance service is provided by means of radar, multilateration and/or ADS-B, coupled with VHF voice communications as depicted in State Aeronautical Information Publications (AIP), provided the aircraft is suitably equipped (transponder/ADS-B extended squitter transmitter) (see Note 1 below).

[NAT Doc 007, ¶1.8.3] The DLM is not applicable to aircraft operating in: Certain categories of flights may be allowed to plan and operate through the mandated airspace with non-equipped aircraft. (See also NAT OPS Bulletin 2017-001.) Charts providing an indication of the likely extent of the NAT ATS Surveillance airspace are included in Attachment 8. Details will be promulgated in the future via State AIP.

More About this . . .

Controller-Pilot Data Link Communications.

What I don't have: ADS-C

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] You can’t operate FL 290 - FL 410 anywhere in the NAT HLA.

Where I can go . . .

Same as CPDLC, above.

Why . . .

[NAT Doc 007, ¶1.8.1] The NAT Data Link Mandate (DLM) requires aircraft to be equipped with, and operating, CPDLC and ADS-C in the NAT region. Currently, the mandate incorporates FL290 to FL410 inclusive.

[NAT Doc 007, ¶1.8.2] The DLM is not applicable to aircraft operating in:

  • Airspace north of 80° North;
  • New York Oceanic East flight information region (FIR);
  • Airspace where an ATS surveillance service is provided by means of radar, multilateration and/or ADS-B, coupled with VHF voice communications as depicted in State Aeronautical Information Publications (AIP), provided the aircraft is suitably equipped (transponder/ADS-B extended squitter transmitter) (see Note 1 below).

[NAT Doc 007, ¶1.8.3] The DLM is not applicable to aircraft operating in: Certain categories of flights may be allowed to plan and operate through the mandated airspace with non-equipped aircraft. (See also NAT OPS Bulletin 2017-001.) Charts providing an indication of the likely extent of the NAT ATS Surveillance airspace are included in Attachment 8. Details will be promulgated in the future via State AIP.

More About this . . .

Automatic Dependent Surveillance - Contract.

What I don't have: More than one LRNS

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] You can’t fly in most of the airspace, with a few exceptions.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] For a full crossing, use the Blue Spruce routes. You only need a single LRNS - and HLA approval if using them between FL 285 - FL 420. You need HF for the ones that enter Shanwick OCA. You can use Tango 9 with a single LRNS, but T213, T13 and T16 need two.

Why . . .

[NAT Doc 007, ¶1.4.1] Routes for Aircraft with Only One LRNS. A number of special routes have been developed for aircraft equipped with only one LRNS and carrying normal short-range navigation equipment (VOR, DME, ADF), which require to cross the North Atlantic between Europe and North America (or vice versa). It should be recognised that these routes are within the NAT HLA, and that State approval must be obtained prior to flying along them. These routes are also available for interim use by aircraft normally approved for unrestricted NAT HLA operations that have suffered a partial loss of navigation capability and have only a single remaining functional LRNS. Detailed descriptions of the special routes known as ‘Blue Spruce Routes’ are included in Chapter 3 of this Document. Other routes also exist within the NAT HLA that may be flown by aircraft equipped with only a single functioning LRNS. These include routings between the Azores and the Portuguese mainland and/or the Madeira Archipelago and also routes between Northern Europe and Spain/Canaries/Lisbon FIR to the east of longitude 009° 01' W (viz.T9). Other routes available for single LRNS use are also established in the NAT HLA, including a route between Iceland and the east coast of Greenland and two routes between Kook Islands on the west coast of Greenland and Canada.

[NAT Doc 007, ¶1.4.2] If this single LRNS is a GPS it must be approved in accordance with FAA TSO-C129 or later standard as Class A1, A2, B1, B2, C1 or C2, or with equivalent EASA documentation ETSO- C129a. Some States may have additional requirements regarding the carriage and use of GPS (e.g. a requirement for FDE RAIM) and flight crews should check with their own State of Registry to ascertain what, if any, they are.

More About this . . .

Oceanic Loss of Long Range Navigation

What I don't have: Transponder

Where I can't go . . .

You cannot fly in the NAT region, at all.

Why . . .

[NAT Doc 007, ¶6.8.1] All aircraft operating as IFR flights in the NAT region shall be equipped with a pressure-altitude reporting SSR transponder.

More About this . . .

Transponder Modes and Codes

What I don't have: TCAS 7.1

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] Nowhere. It’s needed in the entire NAT region. And the whole world.

Why . . .

[NAT Doc 007, ¶6.9.1] Turbine-engined aircraft having a maximum certificated take-off mass exceeding 5,700 kg or authorized to carry more than 19 passengers are required to carry ACAS II in the NAT region. The technical specifications for ACAS II are contained in ICAO Annex 10 Volume IV. Compliance with this requirement can be achieved through the implementation of traffic alert and collision avoidance system (TCAS) Version 7.1 as specified in RTCA/DO-185B or EUROCAE/ED-143.

More About this . . .

Traffic Alert and Collision Avoidance System (TCAS)

What I don't have: ETOPS

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] Further than 60 minutes from adequate airports – unless you’re not operating a commercial flight, or have an exemption.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] First, ATC doesn’t care about your ETOPS approval status. This part is really up to you. If you’re operating a noncommercial flight, or have 3+ engines, then don’t worry about ETOPS. If you are required to fly ETOPS, but don’t have it (recent engine change, for example) – then you’ll have to pick out a route that stays within 60 minutes of adequate airports. That probably means staying within 60 mins of BIKF-BGBW-CYYR. There aren’t any 60 minute options running straight across.

Why . . .

[NAT Doc 007, ¶16.6.22] A large portion of NAT crossings are ETOPS operations. ETOPS rules require that one or more suitable enroute alternate airports are named prior to dispatch and then monitored while aircraft are enroute. Enroute alternate airports in the NAT region are limited to those in the Azores, Bermuda, Greenland and Iceland. In determining ETOPS alternate minima, the dispatcher must consider weather conditions, airport conditions (in addition to simple runway lengths), navigation approach aids, and the availability of ATS and ARFF facilities.

More About this . . .

Extended Operations (ETOPS)

What I don't have: RNP 4

What I don't have: RNP 10

What I don't have: HF

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] Shanwick will not welcome you. Stay out of their airspace, but the others may approve you. US operators should note: N-reg aircraft are required to have functioning HF for overwater ops.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] Other OCA’s may approve Satcom for primary comms. If you’re making a full NAT crossing, then you’re basically going via Iceland. One example route is RATSU-ALDAN-KFV–EPENI–63N30W–61N40WOZN-58N50W-HOIST-LOACH-YYR. Canada publishes two routes that can be flown VHF only, without prior approval: below FL 195, routing Iqaluit (Frobay) – Sondre Stromfjord – Keflavík. FL 250 or above, routing Goose VOR – Prins Christian Sund (or Narsarsuaq) – Keflavik. You still need HLA approval to go above FL285. Gander will probably approve other routes without HF, but ask ATC nicely first. In general, crossing from Greenland-Canada south of 60N, at FL200 or above, should be fine.

Why . . .

[NAT Doc 007, ¶4.2.12] Aircraft with only functioning VHF communications equipment should plan their route according to the information contained in the appropriate State AIPs and ensure that they remain within VHF coverage of appropriate ground stations throughout the flight. VHF coverage charts are shown in Attachment 4. Some may permit the use of SATVOICE to substitute for or supplement HF communications. However, it must also be recognised that the Safety Regulator of the operator may impose its own operational limitations on SATVOICE usage. Any operator intending to fly through the NAT HLA without fully functional HF communications or wishing to use an alternative medium should ensure that it will meet the requirements of its State of Registry and those of all the relevant ATS providers throughout the proposed route.

More About this . . .

High Frequency (HF) Radio.

What I don't have: SELCAL

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] Fly wherever you like, but get the F/O to do radios for this leg. Listening watch required even if you have CPDLC running.

Why . . .

[NAT Doc 007, ¶6.1.22] When using HF, SATVOICE, or CPDLC, flight crews should maintain a listening watch on the assigned frequency, unless SELCAL equipped, in which case they should ensure the following sequence of actions:

a) provide the SELCAL code in the flight plan; (any subsequent change of aircraft for a flight will require refiling of the flight plan or submitting a modification message (CHG) which includes the new registration and SELCAL);

b) check the operation of the SELCAL equipment, at or prior to entry into oceanic airspace, with the appropriate radio station. (This SELCAL check must be completed prior to commencing SELCAL watch); and

c) maintain thereafter a SELCAL watch.

More About this . . .

Selective Calling (SELCAL)

What I don't have: PBCS

Where I can't go . . .

[Ops.Group NAT Quick Reference Guide] Along the core NAT Tracks between FL 350 - 390.

These core tracks are often suspended during extended periods of low traffic volume, spacing out the tracks for use by non-PBCS aircraft.

Where I can go . . .

[Ops.Group NAT Quick Reference Guide] PBCS for the NAT means having both RCP240 (4 minute comms loop) and RSP180 (3 minute position reporting). If you’re missing approval for either, then you can fly anywhere other than long the core NAT tracks FL 350 - 390.

Why . . .

[NAT Doc 007, ¶1.10.2] Within the OTS the 42.6km (23NM) lateral separation minimum is implemented by applying 42.6km (23 NM) lateral spacing through whole and half degrees of latitude between PBCS designated NAT OTS Tracks between flight levels FL 350-390 inclusive, except when the OTS occurs in the New York OCA East. In the OTS this PBCS-based separation implementation supersedes and replaces the previous trials of RLatSM. In addition to requiring RNP-4 Approval, Operators must appreciate that unlike the filing criteria for the half degree spaced RLatSM Tracks, the simple equipage and operation of CPDLC and ADS-C will not be a sufficient criteria for planning and flying on the designated PBCS-based OTS Tracks. To utilize these tracks the aircraft must have formal State Authorization for filing RCP 240 and RSP 180.

More About this . . .

Performance Based Communications and Surveillance (PBCS)

Summary of Requirements

How do you know where you can fly? It all depends on your Performance Based Communications, Navigation, Surveillance capabilities. The Navigation we know about: that's PBN, after all. The rest is now being called PBCS, at least tentatively.

If you have the following equipment: You can fly:
Communications Navigation Surveillance
VHF VOR, DME, ADF Mode C Limited parts of the NAT HLA
HF (in Shanwick OCA) 1 LRNS VHF / HF Position Reports Limited parts of the NAT HLA

Note that we are talking about equipment for these parts of the airspace. Click on the links in the right column to learn about just how limited this can be. If you want greater access, you will need communications, navigation, and surveillance capabilities and those require authorizations.

If you have the following authorizations: You can fly:
Communications Navigation Surveillance
HF RNP 10 and 2 LRNS HF Position Reports NAT Tracks, NAT HLA
(Except FL350-390)
CPDLC RNP 10 and 2 LRNS ADS-C NAT Tracks, NAT HLA
(All Flight Levels)
*
CPDLC / RCP 240 RNP 4 and 2 LRNS ADS-C / RSP 180 NAT Tracks, NAT HLA
(All Flight Levels)

* The NAT Tracks between FL350 - 390 require RCP 240 and RSP 180.

A Summary of Authorizations

  • A056 — Data Link Communications (you will need this for ADS-C and CPDLC)
  • B036 — Required Navigation Performance Airspace (you will need this for RNP-4 or RNP-10)
  • B039 — North Atlantic High Level Airspace (NAT HLA), formerly North Atlantic Minimum Navigation Performance Specifications (NAT/MNPS) Airspace
  • B046 — Reduced Vertical Separation Minimum (RVSM) Airspace

NAT Tracks

The Organized Track System (OTS) carries with it all the restrictions of flying in the NAT HLA plus a few more. You must also be careful in that there are several layers of authorizations involved. You could be permitted the lower altitudes and standard spacing, all altitudes with the chance of decreased longitudinal spacing, and all altitudes with the chance of decreased longitudinal and lateral spacing.

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Photo: Example of Daytime Westbound NAT Organized Track System, NAT Doc 007, Figure 2.
Click photo for a larger image

[NAT Doc 007, ¶2.1]

  • 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 uni-directionally, 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 flight levels normally associated with the OTS are FL310 to FL400 inclusive. These flight levels, and their use have been negotiated and agreed by the NATS ATS providers and are published as the Flight Level Allocation Scheme (FLAS). The FLAS also determines flight levels available for traffic routing partly or wholly outside of the OTS as well as flights operating outside of the valid time periods of the OTS; often referred to as “transition times’.
  • The hours of validity of the two Organised Track Systems (OTS) are as follows:
    • (Westbound) Day-time OTS 1130 UTC to 1900 UTC at 30°W
    • (Eastbound) Night-time OTS 0100 UTC to 0800 UTC at 30°W

    Note: Changes to these times can be negotiated between Gander and Shanwick OACCs 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 OACCs when required, but these should normally be transparent to operators.

  • Use of the OTS tracks is not mandatory Aircraft may flight plan on random routes which remain clear of the OTS or may fly on any route that joins, leaves, or crosses the OTS. Operators must be aware that while ATC will make every effort to clear random traffic across the OTS at requested levels, re-routes or significant changes in flight level from those planned are very likely to be necessary during most of the OTS traffic periods. A comprehensive understanding of the OTS and the FLAS may assist flight planners in determining the feasibility of flight profiles.

[NAT Doc 007, ¶2.4]

  • 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.
  • It should also be recognised that during these times there is often a need for clearances to be individually co-ordinated between OACCs 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 OACC prior to filing of the flight plan to ascertain the likely availability of required flight levels.

PBCS Tracks

[NAT Doc 007, ¶4.1.11] Flights which are planned to follow an OTS track for its entire length (during the OTS periods) may plan any of the levels published for that track, keeping in mind PBCS and DLM requirements.

Note: PBCS tracks will be identified in Note 3 of the OTS message. Operators planning to operate in the altitude band FL350-390 on the PBCS OTS are subject to equipage and authorization requirements as outlined in NAT OPS Bulletin, “Implementation of Performance Based Separation Minima”.

Keeping Up-to-Date

In case you were thinking I was joking about this page being out of date as soon as it was written, I was not. There are so many players out there, around the world, and no central mechanism to keep everyone else current. So you can just do your best. Here are my methods.

Good sources to monitor for changes:

  • NAT OPS Bulletins — available at www.icao.int/EURNAT/, following “EUR & NAT Documents”, then “NAT Documents”, in folder “NAT OPS Bulletins”.
  • NBAA Air Mail — https://www.nbaa.org/airmail/), several forums, including one for international operations. (Membership required.)
  • OpsGroup — ops.group, a platform for pilots, controllers, dispatchers, and managers to ask questions, provide answers, and to learn from peers. (Membership required.)

ICAO Nat Doc 007, North Atlantic Operations and Airspace Manual, v. 2021-1, applicable from February 2021