ICAO North Atlantic (NAT) High-Level Airspace (HLA) & Business Jet Navigation Compliance

Flying across the North Atlantic isn’t just about having the range—it’s about meeting strict ICAO navigation and communication standards within the NAT HLA airspace. This guide explains what North Atlantic (NAT) High-Level Airspace (HLA) is, why it matters for flight operators, and how to maximize business jet flight planning and schedule management to meet all requirements. From navigation approvals to datalink procedures, we break down what operators need to know for compliant, safe crossings.

What is North Atlantic (NAT) High-Level Airspace (HLA)?

The North Atlantic (NAT) High-Level Airspace (HLA) is the special oceanic region used for flights between North America and Europe. It extends roughly from FL285 to FL420 (FL: Flight Level) in the Atlantic (above ~FL280 in the west) within the Shanwick (UK), Gander (Canada), New York, Reykjavik (Iceland), Santa Maria (Portugal) and Bodø (Norway) oceanic control areas. (Shannon and Brest Oceanic Transition Areas are excluded.)

This area was formerly called the “NAT MNPS” (Minimum Navigation Performance Specification) airspace, but since 2016 it has been redesignated NAT HLA to emphasize performance-based navigation. In practical terms, any business jet flying NAT HLA must have formal approval from its State of Registry/operator (e.g. FAA OpSpec B039 or equivalent). Operators must file NAT HLA tracks when crossing this region, and include the letter “X” in Item 10A of the ICAO flight plan to indicate NAT HLA approval.

 

All flights in NAT HLA must also meet RVSM (Reduced Vertical Separation) rules (FL290–410 in NAT are RVSM levels) and file accordingly. Outside the HLA (FL280 and below westbound, FL270 and below eastbound, or above FL420), NAT HLA approvals are not required, but NAT HLA tracks and clearances are only available at the higher levels. In other words, business jets without NAT HLA/RVSM approval can still cross the Atlantic (at FL280/270 or FL430), but must avoid FL290–410 in the designated oceanic areas. (Special exemptions exist for delivery, ferry or humanitarian flights subject to ATC permission.)

North Atlantic Track System (OTS) and Clearances

Most NAT crossing flights use the North Atlantic Track System (OTS). Each day, Shanwick and Gander publish westbound and eastbound NAT tracks (e.g. “NAT 12”, “T9”, etc.) based on winds. A typical clearance in the NAT HLA will specify one of these tracks (or a random route between published waypoints) and a cruising Mach number. Under Mach Number Technique longitudinal separation, each aircraft must maintain its cleared Mach for the ocean crossing (New NAT rules now allow “resume normal speed” clearances once established, but a fixed Mach is still assigned until that clearance).

 

Oceanic clearances are usually delivered via CPDLC (Data Link) or (High Frequency) HF radio. Because the NAT HLA is beyond VHF range much of the time, flights must have HF radio (or SATCOM voice) and remain tuned/listening on assigned frequencies. Position reports (via ADS‑C or HF) at strategic waypoints (e.g. oceanic entry fixes) are mandatory

Navigation Performance & Equipment Requirements

NAT HLA operations require precision RNAV/PBN navigation. Specifically, ICAO NAT Doc 007 mandates navigation accuracy of RNP-10 or RNP-4 in NAT HLA. In practice:

 

• RNP-10 (RNAV-10) means the aircraft’s total lateral error must remain within 10 NM of clearance 95% of the time. This allows 50 NM lateral separation on eastbound tracks (e.g. New York OCE East).
• RNP-4 means much tighter lateral error (4 NM). PBCS tracks (see below) require RNP-4.

 

Almost all modern business jets (e.g. Falcon 8X, Cessna Citation, Gulfstream types) can meet RNP-10; many can obtain RNP-4 approvals by virtue of dual FMS/IRS/GPS systems. ICAO still uses the term “RNAV 10 (RNP 10)” for consistency, even though true RNP-10 (with onboard monitoring) differs from older RNAV-10.

In addition to accuracy, redundant long-range navigation (LRN) systems are required. Specifically: the aircraft must be equipped with at least two independent LRNS units – for example, a dual-FMS/GPS or dual-IRS configuration. Each LRNS must continuously display position relative to the cleared track. (FAA Advisory Circulars (ACs) and ICAO PBN guidance say this can be two INSs, or one INS + one GNSS, etc). For example, a Dassault Falcon 8X has triple IRS/GPS systems, easily satisfying this. A lighter jet like the Citation M2 Gen2 typically has dual FMS/GPS units.

 

Importantly, each LRNS must meet high integrity standards. Even with two LRNS, NAT HLA approval requires dual Flight Management Computers (FMS/IRS) – a single FMS driving two INS cannot be accepted. In short, one FMS + one standby INS = 1 LRNS (not two). To get NAT HLA approval, airlines/operators usually demonstrate dual FMCS or dual cross-coupled IRS. (See ICAO note: “a single INS is one LRNS; an FMS with inputs from one or more IRS is also one LRNS”).

 

For orientation and backup, aircraft should also carry normal short-range nav aids (VOR/DME/ADF) and a certified compass system. ICAO Annex 6 and NAT Doc 007 emphasize that flight crews must have a time-synchronized clock (e.g. synced to UTC via GPS) for accurate waypoint time reporting.

Flight Planning & Approvals

Operators (dispatchers and flight planners) must ensure all paperwork and clearances are in order before the flight:

State Approval

Obtain NAT HLA approval (e.g. FAA LOA B039 for U.S. Part 91/135; EASA/UK approval for EU-registered jets) if you intend to fly FL285–420 in the NAT. This approval confirms the aircraft and crew meet NAT HLA requirements. Without it, you are restricted to FL280/270 westbound or FL430.

 

•  A Citation M2 Gen2 operator would need LOA B039 as part of its FAA Ops Specs to plan FL350 across the Atlantic.

Flight Plan Item 10A

Insert the letter “X” in Item 10A of the ICAO flight plan to indicate NAT HLA compliance (This alerts ATC that you are approved for HLA ops.) Also include accurate PBN/RNP codes in Item 18 (e.g. PBN/A1B2 or SPPN/A1B2 or simply RNP4, depending on the FMS certification).

 

• For example, an aircraft with two FMS/GPS and RVSM should file something like PBN/A1B2C3 to show RNP-10 and RNP-4 capabilities.

Route Selection

Check the latest NAT OTS message (shipped daily by Shanwick/Gander). Plan to fly one of the published NAT tracks or a random route of ATC’s approval. Calculate fuel based on the fixed Mach and track. Always carry the current NAT track chart (e.g. NOAA North Atlantic Route Chart) in the dispatch packet for reference.

Comms

Ensure HF/SATCOM is serviceable. Pick oceanic HF frequencies before departure. Flight crews should verify the Selective Calling System (SELCAL). (Some ATC units require a pre-departure HF check-in.) If Datalink is used, verify CPDLC/ADS-C connectivity pre-flight.

Alternate Airports

Because of the remote route, pick suitable alternates. Common NAT alternates include Keflavik (BIKF, Iceland), Sondrestrom (BGSD, Greenland), Goose Bay (CYYR, Canada) or Shannon (EINN, Ireland), depending on routing. Greenland’s Nuuk (BGGH) runway expansion (Nov 2024) means Nuuk is now a viable NAT alternative. Include alternate planning in the IFR flight plan and briefing.

Flight Crew Briefing/Training

Crews should be familiar with NAT procedures (position reporting, Mach technique, contingency plans, etc.). For example, pilots must know to synchronize their FMS clocks to UTC before NAT entry and to log waypoint times accurately. Dispatchers should emphasize “what-ifs” (e.g. data link or GPS failures) and review NAT guidance (Appendix of NAT Doc 007) with crews.

Example Flight-Operations Scenarios

Citation M2 Gen2 – Transatlantic Dash

Suppose a Cessna Citation M2 Gen2 is flying Boston Logan International Airport (BOS)→ London Heathrow Airport (LHR). It departs at FL350. The M2’s dual FMS/GPS units meet RNAV-10 (RNP-10) requirements. Before departure, the dispatcher confirms LOA B039 (NAT HLA) and checks RVSM approval. In the flight plan, “X” is entered in Item 10A and “PBN/A1B2” (RNAV 5, RNP-1, RNP-4) in Item 18.

 

The tracker fetches the daily NAT OTS, and dispatch files “FPL GIBAL GYMAT DCT” along a westbound NAT track. ATC issues an oceanic clearance (e.g. “CLP 300 NAT60 CIONO5 JFK RRNNY” – a hypothetical route/Mach). En route, the crew uses CPDLC for waypoint clearances and relies on ADS-C reports.

 

They maintain HF watch on 3.136 MHz for position or reroutes. The navigator crew is prepared: if the GPS signal were lost, the dual IRS would still provide RNP-4‑level accuracy for the crossing. In descent, a failure of CPDLC would have required informing Shanwick Oceanic (as per NAT contingency procedures).

Falcon 8X – PBCS Track

A Falcon 8X (with triple IRS/GPS and full FANS) flies Amsterdam Airport Schiphol (EHAM) → Montréal–Trudeau International Airport (CYUL) via NAT. It is capable of RNP-4 and has up-to-date CPDLC/ADS-C. Dispatchers plan an optimal high-altitude track (maybe a PBCS track for 23 NM separation) to save fuel.

 

In the flight plan they declare RNP-4 and the required performance (RCP240/RSP180). The crew receives clearance on NAT’s PBCS-designated track and climbs to FL380. The Falcon’s integrated systems report flawlessly via ADS-C (meeting the RSP180 spec) and handle data-link clearances (RCP240). Thanks to PBCS approval, the 8X enjoys tighter spacing and a shorter routing than older RNAV-10 flights.

Pilatus PC-24 – Single LRNS Flight

The Pilatus PC-24 is a small twin-jet business aircraft, typically with a single GPS/INS (one long-range unit). In 2024 it could use the special “Blue Spruce” routes if properly approved. For example, a PC-24 flying from Newfoundland to the Azores would normally climb to FL310 and follow Blue Spruce fixes via Greenland and Iceland, under special one-LRNS procedures.

 

However, ICAO has deleted all Blue Spruce routes as of Mar 20, 2025. That means a PC-24 with only one FMS/GPS cannot fly FL285–420 on a random route the way larger jets do. After March 2025, single-LRNS aircraft must either:

 

• Fly below/above NAT HLA (e.g. cruise FL280 westbound, then step-climb to FL290 on the European side), or
• Use the northern surveillance corridors: e.g. climb in VHF/ADS‑B requirements over Greenland–Iceland (GOTA corridor) where reduced NAT requirements apply.

Recent Regulatory Updates (2025)

ICAO’s newest NAT Doc 007 (2025 edition) took effect on 20 March 2025. It reorganizes guidance but keeps the core requirements. The main change relevant to operators is the elimination of the old “Blue Spruce” one-LRNS routes. Those special Greenland/Iceland tracks have been removed, reflecting that modern jets rarely need them.

 

Consequently, any aircraft lacking full NAT HLA equipment must now use the known surveillance corridors (e.g. Gander’s VHF/ADS-B corridor via Reykjavik) or avoid FL285–420 altogether. Other changes include updates on space-weather and GNSS interference procedures (crews should be briefed on solar-event contingency as per new NAT guidance) and refinements to position-reporting requirements.

 

At Just Aviation, we simplify the complexity of transatlantic operations for business jet operators. From securing NAT HLA approvals to ensuring your aircraft meets all ICAO 2025 requirements, our team provides end-to-end support for seamless North Atlantic crossings. Trust us to keep your missions compliant, efficient, and on time—no matter the route or regulation.