Oceanic Clearance on the North Atlantic: How It Works
Before entering oceanic airspace, an aircraft normally needs an oceanic clearance. It tells the crew exactly which route and level they may fly across the ocean.
Getting a clearance
- How to obtain a clearance from each oceanic centre is published in the State AIPs.
- In many cases the clearance delivery frequency is given in the AIP, on the high level charts or in the OTS track message.
- At airports close to oceanic boundaries, it may be necessary to obtain the clearance before departure.
- If a flight requests a track from the OTS, the request should include the next preferred alternative track.
- Pilots should always try to obtain the clearance before entering the oceanic area. If there is a difficulty, they should not hold while waiting unless ATC directs it.
What a clearance contains
A full clearance gives the route from the oceanic entry point to the exit point. A clearance on an organised track can be given in an abbreviated form, and acknowledged with an abbreviated readback that includes the TMI number of the current NAT Track Message. If the TMI is not available or is incorrect, air traffic services issue a full route clearance and require a full readback.
Where errors happen
Many track-keeping errors in the NAT HLA come from crews programming the navigation systems with incorrect waypoint data. ICAO North Atlantic operations guidance recommends checking the aircraft's position 10 minutes after each waypoint, and warns that truncated displays cause persistent problems.
Clearance procedures differ by oceanic centre and are changing in places, so always follow the current AIP and NAT Doc 007.
Open the nat track message guide
FAQ
Can I hold at the oceanic boundary while I wait for a clearance?
Pilots should not hold while waiting unless ATC directs it. They should try to obtain the clearance before entry.
Why does the readback include the TMI?
It lets controllers confirm that the crew is using the current track message.
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- What Is in an ICAO Flight Plan? Every Item Explained
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- FAA Part 117 Explained: Flight Time, Duty Period and Rest
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- How to Read a NOTAM: ICAO Format Explained
- EASA Flight Time Limitations: The Basics and How They Differ from FAA Part 117
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- Adequate vs Suitable Aerodrome: What Is the Difference?
- How to Calculate an Equal Time Point (ETP)
- EDTO Approval and Dispatch Requirements Explained
- The North Atlantic Organised Track System (NAT OTS) Explained
- The NAT Track Message and TMI Number Explained
- NAT High Level Airspace (HLA) Requirements Explained
- NAT Contingency Procedures and SLOP Explained
- Polar Routes Explained: What Is Special About Flying Near the Poles
- Polar Operations Requirements Checklist (FAA)
For training and reference only. Check official sources before any real flight.