Requirements for Navigation in Northern Domestic Airspace and Polar Regions

Effective Date: 1 March 2017

Version in effect: 3 (revised 6 July 2023)

Reference: TAM Part 2, Chapters 5, 6 and 7

OPI / Telephone: DTAES 6-4 / 819-939-4714

1. Purpose

1.1 This Technical Airworthiness Authority (TAA) Advisory sets out the equipage requirements for navigating within the Northern Domestic Airspace (NDA) during night and Instrument Flight Rules (IFR) operations by using True Heading outputs and long-range navigation capabilities. The advisory also addresses communication aspects associated with operations in NDA. 

2. Applicability

2.1 This advisory applies to all DND/CAF personnel, as well as their support contractors, who are seeking to obtain an airworthiness approval and Technical Airworthiness Clearance (TAC) to conduct night and/or IFR operations in the NDA, as required by the fleet Statement of Operating Intent (SOI) or by Royal Canadian Air Force (RCAF) National Defence Flying Orders.

2.2 The methodology used in this advisory assesses the impact of high latitude (NDA and Polar) operating conditions on the function and performance of equipment required for night and IFR operations. The Flight Manual (FM) will be annotated to identify any applicable limitation or restriction.

3. Related Material

3.1 Definitions

3.1.1. Nil.

3.2 References

3.2.1 The following references should be used in conjunction with this advisory, as appropriate:

1. Federal Aviation Administration (FAA) Order 8900.1 – FAA Flight Standards Information Management System, Volume 4 – Air Navigation and Operational Authorizations, Chapter 1 – Air Navigation, Communications, and Surveillance, Section 5 – Safety Assurance System: Special Navigation Areas of Operation, paragraphs 4-103c
2. Canadian Aviation Regulations (CARs), Part VI, Subpart 5, Paragraph 605.16(1)(g)
3. B-GA-100-001/AA-000 – National Defence Flying Orders
4. Transport Canada Civil Aviation (TCCA) – Transport Canada Designated Airspace Handbook, TP1820E
5. Nav Canada, Aeronautical Information Publication (AIP) Part 2, Enroute 4.3
6. Transport Canada Airworthiness Manual (AWM) Chapter 523 – Normal, Utility, Aerobatic and Commuter Category Aeroplanes (up to Change 523-18)
7. Transport Canada AWM Chapter 523 – Normal Category Aeroplanes (Change 523-18 and later)
8. Transport Canada AWM Chapter 525 – Transport Category Airplanes
9. Transport Canada AWM Chapter 527 – Normal Category Rotorcraft
10. Transport Canada AWM Chapter 529 – Transport Category Rotorcraft
11. MIL-HDBK-516C, Airworthiness Certification Criteria, dated 12 December 2014 or later
12. C-05-005-001/AG-002 – Airworthiness Design Standards Manual (ADSM), Part 3, Chapter 2
13. C-05-005-001/AG-001 – Technical Airworthiness Manual (TAM), Part 2, Chapters 5, 6 and 7

4. Discussion

4.1 Background

4.1.1 Northern Domestic Airspace

4.1.1.1 Canadian Domestic Airspace (CDA) is divided into two main regions – Southern Domestic Airspace (SDA), and NDA (Figure 1). In the NDA, runway headings, tracks, etc., are given in degrees true, rather than magnetic. This is due to the diminishing horizontal component of the earth’s magnetic field in proximity to the magnetic North Pole and its effects on magnetic compass systems.

4.1.1.2 The NDA includes the Northern Control Area (NCA), the Arctic Control Area (ACA) (Figure 2) and all the airspace below the base of these control areas down to the surface of the earth. The FAA (reference 3.2.1.a) designates Canada's NDA as an Area of Magnetic Unreliability (AMU). Although Canadian publications sometimes refer to it as the area of compass unreliability, they are the same. The NDA, NCA and ACA are depicted on all Canadian enroute charts and encompass the northernmost Canadian airspace.

Both civil (reference 3.2.1.b) and military (reference 3.2.1.c, Book 1 of 2, Chapter 8, para 9) operational regulations require a means of establishing direction that is not dependent upon a magnetic source when operating within the NDA. These operational regulations exist because anomalies with the Earth’s magnetic field in the Polar Regions cause erroneous magnetic heading indications. Aircraft, therefore, use True Heading information when flying in the NDA. Appropriately certified navigation equipment, as well as special techniques and/or procedures, are critical to safe operation in polar areas, including the area of magnetic uncertainty (reference 3.2.1.d).

4.1.2 Increased Alignment Times Due to Magnetic Variation and Convergence of the Meridians

4.1.2.1 Conventional magnetic compasses sense magnetic direction by detecting the horizontal component of the earth's magnetic field. Since this horizontal component vanishes near the magnetic poles, magnetic compasses are highly unreliable and unusable in an area of approximately 1,000 NM from each magnetic pole. Within these areas, air navigation tasks are further complicated by very rapid changes in magnetic variation over small distances. For example, when flying between the Magnetic North Pole and the True North Pole, a heading of True North results in a magnetic heading of south (a magnetic variation of 180 degrees).

Figure 1 – Northern and Southern Domestic Airspace

4.1.2.2 The convergence of the meridians (i.e., lines of longitude) presents additional directional complications. When flying "great circle" courses at latitudes greater than 67 degrees, convergence of the meridians can create rapid changes in true headings and true courses with small changes in aircraft position. As a result, relatively small errors in determining the aircraft's actual position can produce very large errors in determining the proper heading to fly and maintain the assigned flight path. When even small errors occur, very large navigation errors can develop over extremely short distances. An extreme example of this phenomenon occurs at the earth's geographic North Pole. Flight in any direction from the exact pole is initially due South.

4.1.3 Navigation in the NDA

4.1.3.1 Navigating in the NDA presents several issues not found anywhere else in the world (other than near the South Pole). Because of these issues, an acceptable method of navigating within the NDA is resorting to long-range navigation systems referenced to True North, by using Inertial and/or GNSS:

1. Inertial Based Navigation Systems. All Inertial Navigation Systems (INS) / Inertial Reference Systems (IRS) / Inertial Reference Units (IRU) can calculate True North-referenced outputs independently from other aircraft systems.
2. GNSS Systems. As of June 2023, according to Nav Canada’s Aeronautical Information Publication – AIP Canada (ICAO), Part 2, Enroute 4.3 (reference 3.2.1.e), the only global operational GNSSs approved for use in Canada are the United States NAVSTAR Global Positioning System (GPS) and the Russian GLONASS. Furthermore, the United States FAA Wide Area Augmentation System (WAAS) can provide position augmentations for use in the CDA. Coverage of the FAA WAAS augmentations is subject to visibility of at least one of the WAAS geostationary satellites. GNSS can output tracks referenced to degrees True, but generally do not provide any heading information. Operationally, a GNSS and an Automatic Direction Finder (ADF) can be used to determine aircraft heading. This heading can then be used to manually set a Directional Gyro, for example.

4.2 Requirements

4.2.1 The applicant is responsible for demonstrating that the installed navigation equipment and overall avionics architecture continues to provide its intended function while operating in the NDA. The appropriate certification basis needs to be identified to ensure that the correct means and methods of compliance are incorporated into the project objectives, safety assessment, test plans and flight manual amendments.

4.2.2 For aircraft designed and certified to civil airworthiness standards, as a minimum, the following Transport Canada Airworthiness Manual (AWM) requirements (references 3.2.1.f to j) or equivalents, as set out in the Airworthiness Design Standards Manual (ADSM) (reference 3.2.1.l), should be included:

1. AWM Section 52X.1301, Function and Installation
2. AWM Section 52X.1309, System Safety
3. AWM Section 52X.1501, 1583 and 1585 Flight Manual
4. AWM Section 52X.1529, Instructions for Continued Airworthiness

4.2.3 The certification basis should be assessed to determine whether any additional airworthiness standards and requirements need to be addressed as a result of any specific design peculiarities.

4.2.4 For aircraft designed and certified to MIL-HDBK-516 (reference 3.2.1.k), the typical requirements should include:

1. Section 4.5 – Operator’s and Maintenance Manual
2. Section 10 – Diagnostics Systems
3. Section 11 – Avionics
4. Section 14 – System Safety

4.2.5 Specific avionics, system safety and FM/AOI requirements, criteria and guidance are identified in this advisory’s Annex A, Annex B and Annex C, respectively. Fleets seeking airworthiness approval to operate in the NDA need to address these requirements as part of their airworthiness certification program.

4.3. Means of Compliance during Type Design Examination

4.3.1 The intent of the Type Design Examination (TDE) is to credit certification activities that have been performed by organizations acceptable to the TAA. However, contrary to the TAA, who assesses the aircraft eligibility to conduct operations in the NDA as part of the type certification process, most airworthiness authorities assess an aircraft’s ability to safely operate in the areas of magnetic unreliability as part of the air operator certification. As a result, granting appropriate credits during a TDE can be challenging, as the type design documentation will not contain information regarding the operational approval of the aircraft and its operators. The applicant can use the following three strategies to demonstrate compliance with this advisory for operations in the NDA:

1. The applicant obtains from an Operator of the aircraft type sufficient operational documentation (e.g., Operations Specifications, Operations Manual extract, etc.) regarding the Operator’s approval to conduct operations in the NDA. This information is required by the TAA to identify any operational limitations or restrictions that may be applicable to the RCAF fleet.
2. The applicant submits criteria tables, completed against the criteria provided in Annex A, Annex B and Annex C of this advisory. During the Type Design Review, the submission is assessed by the TAA (DTAES 3 staff) and, if deemed acceptable, DTAES Subject-Matter Experts (SMEs) (DTAES 6, 7 and 8) will conduct a thorough review of the tables and make recommendations to the TAA (DTAES 3 staff) on the approval of the fleet’s NDA operations. This strategy requires that sufficient acceptable aircraft technical information is available to the applicant to fill the criteria tables.
3. The applicant initiates a design change by using this TAA Advisory as means of compliance to demonstrate safe operations in the NDA.