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NAT High Level Airspace (HLA)

Normal Procedures: Airspace

The North Atlantic High Level Airspace (NAT HLA) was created on 4 February 2016 from the previous Minimum Navigation Performance Specification (MNPS), which was created in the seventies as a way of setting some kind of standard for who could and could not fly the North Atlantic.




Figure: North Atlantic High Level Airspace (NAT HLA), from Flight Service Bureau International Operations Notice 2016-01.

Boundaries of NAT HLA as of 4 February 2016.

[FAA Domestic/International NOTAMS] The boundaries of NAT HLA are planned to remain the same as those for NAT MNPSA with the exception that Bodo Oceanic is planned to be included in NAT HLA. NAT HLA boundaries are planned to include the volume of airspace between Flight Levels (FL) 285 to 420 in the following Oceanic Control Areas (OCA):

  • Gander Oceanic
  • New York Oceanic East
  • Reykjavik
  • Santa Maria
  • Shanwick with the exception of the Brest Oceanic Transition Area (BOTA) and the Shannon Oceanic Transition Area (SOTA)
  • Bodo Oceanic is not currently included in NAT MNPSA, however, it is proposed to be included in NAT HLA as of 4 February 2016.

Outside the NAT HLA

The following are from older sources that are awaiting update.

  • [ICAO Doc 7030, §CAR, ¶] Caribbean — For flights in transit to or from the NAT MNPS airspace, while operating in the control area of the San Juan FIR, a lateral separation minimum of 110 km (60 NM) may be applied. . . . Aircraft must meet the NAT MNPS specifications.
  • [ICAO Doc 7030, §NAT, ¶] North Atlantic — 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.
  • [Transport Canada AIM, ¶2.6] Canada — The airspace from FL330 to FL410 within the lateral dimensions of the NCA [Northern Control Area], the ACA [Arctic Control Area] and the northern part of the SCA has been designated CMNPS airspace.
  • More about: High Latitude Operations.

Note: this is an ever decreasing list. Far off places like Hong Kong once used MNPS but are gravitating toward RNP-4.

Accuracy / Performance Standards

[ICAO NAT Doc 007 § 1.3.3] In terms of accuracy, an aircraft which is approved for operations within NAT MNPS/HLA Airspace prior to January 2015 shall have a navigation performance capability such that:

  1. the standard deviation of lateral track errors shall be less than 6.3 NM (11.7 km);
  2. the proportion of total flight time spent by the aircraft 30 NM (56 km) or more off the cleared track shall be less than 5.3 x 10-4;
  3. the proportion of total flight time spent by the aircraft between 50 and 70 NM (93 and 130 km) off the cleared track shall be less than 13 x 10-5.

[ICAO NAT Doc 007 § 1.3.4] For (MNPS) Approvals issued before January 2013, the State of Registry or the State of the Operator, as appropriate, should have verified that the lateral navigation capability of approved aircraft meets the above specified requirements. For Approvals issued between January 2013 and January 2015 Approvals can have been based on these foregoing navigational performance capabilities or based on the PBN specifications, RNP 10 (PBN application of RNAV 10) or RNP 4. For Approvals issued after January 2015 the navigation system accuracy requirements for NAT MNPSA/HLA operation should only be based on the PBN specifications, RNP 10 (PBN application of RNAV 10) or RNP 4. Although when granting consequent approval for operations in MNPS/NAT HLA airspace, States should take account of the RNP 10 time limits for aircraft equipped with dual INS or inertial reference unit (IRU) systems.

Additionally, in order for the 50 Nms lateral separation minimum to be utilized in the New York Oceanic East the following navigation performance criteria must also be met by aircraft with RNAV 10 (RNP 10) Approvals: -

a) the proportion of the total flight time spent by aircraft 46 km (25 NM) or more off the cleared track shall be less than 9.11 × 10-5; and

b) the proportion of the total flight time spent by aircraft between 74 and 111 km (40 and 60 NM) off the cleared track shall be less than 1.68 × 10-5.

And similarly the additional criteria which must be met by aircraft approved as RNP 4 are as follows : -

c) the proportion of the total flight time spent by aircraft 28 km (15 NM) or more off the cleared track shall be less than 5.44 × 10-5; and

d) the proportion of the total flight time spent by aircraft between 44 and 67 km (24 and 36 NM) off the cleared track shall be less than 1.01 × 10-5.

Note:- In Summary : - From February 2016 the NAT MNPSA is re-designated as NAT HLA. Previously granted MNPS Approvals are valid for NAT HLA operations. Milestone 2 of the MNPS to PBN NAT transition plan was achieved in January 2015. From that date all new North Atlantic MNPS Operational Approvals should have been based upon RNAV 10 (RNP 10) or RNP 4 navigation specifications. Previously issued 6.3NM based MNPS Approvals will continue to be valid for NAT HLA operations but it is important to note that their longevity will be limited. Since subsequently, from January 2020, Milestone 4 of the MNPS to PBN NAT Transition Plan will take effect and the NAT HLA airspace will be re-designated for “PBN Based Operations” and thus from then Aircraft Approvals based on the earlier 6.3NM MNPS standard will no longer be valid.

[ICAO NAT Doc 007 § 1.3.6] In most cases, Operators will be able to select equipment for which performance capability has already been established to the satisfaction of a State of Registry. However, where a completely new navigation system is proposed for use, or where major changes have been made in the technology of an existing system, an evaluation will be necessary, to establish its quality of performance, before authorisation for use as a primary means system can follow. Currently, it has been demonstrated that the requisite accuracies may be achieved using Long Range Navigation Systems, namely INS, IRS or GNSS. Consequently, State approval of unrestricted operation in the NAT HLA airspace may presently be granted to an aircraft equipped as follows:

a) with at least two fully serviceable Long Range Navigation Systems (LRNSs). A LRNS may be one of the following:

  • one Inertial Navigation System (INS);
  • one Global Navigation Satellite System (GNSS); or
  • one navigation system using the inputs from one or more Inertial Reference System (IRS) or any other sensor system complying with the NAT HLA requirement.
  • Note 1: Currently the only GNSS system fully operational and for which approval material is available, is GPS.

    Note 2: A GPS installation must be approved as follows:

    If the two required LRNSs are both GPS, they must be approved in accordance with the current version of FAA Advisory Circular AC-20-138D Appendix 1. AC- 20-138 requires that GPS systems used in Oceanic airspace must have a FDE function. States other than the USA may set their own standards for operational approval of GPS to provide Primary Means of Navigation in Oceanic and remote areas but in all cases these approvals will include the requirement to carry out Pre-Departure Satellite Navigation Prediction Programs (See Chapter 8 - GNSS (GPS) Systems for further details). If, however, GPS serves as only one of the two required LRNSs, then 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 European Aviation Safety Programme (EASA) documentation ETSO-C129a. In this instance individual States vary in their insistence upon the need for the conduct of pre-departure satellite navigation prediction programs (viz.FDE /RAIM).

    Note 3: Currently equivalent approval material for GLONASS is not under development but it will need to be available prior to approval of any GLONASS equipped aircraft for NAT HLA operations.

b) each LRNS must be capable of providing to the flight crew a continuous indication of the aircraft position relative to desired track.

c) it is also highly desirable that the navigation system employed for the provision of steering guidance is capable of being coupled to the autopilot.

Note : Some aircraft may carry two independent LRNS but only one FMCS. Such an arrangement may meet track keeping parameters but does not provide the required redundancy (in terms of continuous indication of position relative to track or of automatic steering guidance) should the FMCS fail; therefore, in order to obtain NAT HLA certification, dual FMCS is required to be carried. For example: a single INS is considered to be one LRNS; and an FMCS with inputs from one or more IRS/ISS is also considered to be a single LRNS.

Documentation / Certification

Letter X for ICAO flight plan

[FAA Domestic/International NOTAMS] Item 10a of the ICAO flight plan will continue to be annotated with the letter “X” to indicate that the aircraft meets the requirements for HLA operations.

[ICAO NAT Doc 007 § 1.2.1] All flights within NAT HLA airspace must have the approval of either the State of Registry of the aircraft, or the State of the Operator. Aircraft operating in RVSM Airspace are required to be compliant with the altimetry Minimum Aircraft System Performance Specifications (MASPS) and hold an issued approval. Approval for NAT HLA operations will require the checking by the State of Registry or State of the Operator, of various aspects affecting navigation performance. These aspects include: the navigation equipment used, together with its installation and maintenance procedures; plus the crew navigation procedures employed and the crew training requirements

[ICAO NAT Doc 007 § 1.2.2] Since NAT HLA airspace is now designated as RVSM airspace at all levels (i.e. FL290-410 inclusive) specific State RVSM Approval is also required to operate within NAT HLA airspace.

14 CFR 135 Approval

[8900.1, Volume 4, Chapter 1, Paragraph 4-98.D.] All NAT/MNPS approvals are granted by issuing OpSpec paragraph B039, Operations within North Atlantic (NAT) Minimum Navigation Performance Specifications (MNPS) Airspace, and by adding that area of en route operation to paragraph B050, Authorized Areas of En Route Operation, Limitations, and Procedures, of the standard OpSpecs.

14 CFR 91 Approval

[14 CFR 91, §91.705] Operations within airspace designated as Minimum Navigation Performance Specification Airspace.

  1. Except as provided in paragraph (b) of this section, no person may operate a civil aircraft of U.S. registry in airspace designated as Minimum Navigation Performance Specifications airspace unless—
    1. The aircraft has approved navigation performance capability that complies with the requirements of appendix C of this part; and
    2. The operator is authorized by the Administrator to perform such operations.
  2. The Administrator may authorize a deviation from the requirements of this section in accordance with Section 3 of appendix C to this part.

[14 CFR 91, Appendix C, §3] Air traffic control (ATC) may authorize an aircraft operator to deviate from the requirements of §91.705 for a specific flight if, at the time of flight plan filing for that flight, ATC determines that the aircraft may be provided appropriate separation and that the flight will not interfere with, or impose a burden upon, the operations of other aircraft which meet the requirements of §91.705.

Effect on FAA Operations Specifications (OpSpec), Management Specifications (MSpec) and Letters of Authorization (LOA) B039.

[FAA Domestic/International NOTAMS] (B039 is “Operations in North Atlantic Minimum Navigation Performance (NAT MNPS) Airspace”). The following guidance applies:

  1. OpSpec/MSpec paragraph B039 and LOA B039 approvals issued to authorize MNPSA operation will remain valid for NAT HLA operations until 31 December 2019, however, new B039 OpSpecs, MSpecs and LOAs for NAT HLA are being developed. This provision allows OpSpec/MSpec paragraph B039 and LOA B039 approvals based on the NAT MNPS navigation specification to be “grandfathered” (i.e., aircraft not yet approved for Required Navigation Performance 10 (RNP 10) or RNP 4 may continue to operate in NAT HLA).
  2. A new OpSpec/MSpec/LOA B039 tentatively entitled “Operations in North Atlantic High Level Airspace (NAT HLA)” is under development. The FAA will keep U.S. operators informed on plans to introduce the new B039 HLA authorizations.

Example Compliance


Figure: Example MNPS LOA Extract, from Eddie's sordid past.

Under 14 CFR 91, if you have a similar statement in your AFM or POH, you are good to go.

Under 14 CFR 135, you will also need OpSpec B039:


Figure: Example OpSpec B039 Extract, from Eddie's sordid past.

Book Notes

Portions of this page can be found in the book International Operations Flight Manual, Part III, Chapter 7.


14 CFR 91, Title 14: Aeronautics and Space, General Operating and Flight Rules, Federal Aviation Administration, Department of Transportation

FAA Domestic/International NOTAMs.

FAA Orders 8400 and 8900

Flight Service Bureau International Operations Notice 2016-01, North Atlantic MNPS to High Level Airspace

ICAO Doc 7030, Amendment 1, International Civil Aviation Organization, 8 January 2009

Jeppesen Airway Manual

NAT Doc 007, North Atlantic Operations and Airspace Manual Doc 007, v 2016-1

NAT OPS Bulletin 2016_001, Re-naming of the Nat MNPSA to NAT HLA, Effective 4 February 2016

Transport Canada Aeronautical Information Manual

Revision: 20160302