The NAT DLM Exempt Area

Welcome back to Jump Seat. Today we want to review the NAT DLM Exempt (ATS Surveillance) area and how recent changes may impact your operation. 

If you have a non-CPDLC equipped aircraft and are planning a flight between North America and Europe, you may already be familiar with the limitations for what airspace you can flight plan in. NAT DLM (Data Link Mandate) Airspace vertical limits are between FL290 and FL410. Operators also have the option to fly north over Greenland and Iceland as well. We are finding, however, that many such operators assume that they need to take the northerly Blue Spruce Routes when they cross the North Atlantic through these areas. If you have two Long Range Navigation Systems (for example, INS/IRS and GNSS) you can save yourself some time and effort. Read on to learn more.

Birth of the Blue Spruce Routes 

During World War II, the North Atlantic Air Ferry Routes were used primarily to transport short range single-engine military aircraft from the US to Europe for use in combat areas. These routings (which later became known as the Blue Spruce Routes) allowed for tech stops at airports along the route and used ground-based navigational aids for aircraft with limited equipment. 

It was from these beginnings that the Blue Spruce Routes we know today were born. They are still the only crossing option available for aircraft with just one Long Range Navigation System onboard. 

Gander Oceanic Transition Area (GOTA) 

The first area we cover is found off the northeast coast of Canada and is known as the Gander Oceanic Transition Area (GOTA). GOTA, highlighted in the green border below, is actually within the NAT DLM airspace but it meets qualifications to be considered ATS Surveillance (DLM Exempt Airspace) based on implementation of the installation of ADS-B, VHF and Radar. This means that non-datalink equipped aircraft (without FANS CPDLC / ADS-C) can fly through this area even though it’s found within the NAT DLM Boundaries. Note: You still require NAT HLA Authorization through GOTA and through the ATS Surveillance area across Greenland and Icelandic airspace between FL285 and FL420.  

Gander Oceanic Control Area in Southern Greenland 

The second area of interest is found over southern Greenland, highlighted by the orange border above. Gander Oceanic Control Area (OCA) has authority over this area above FL195 and has stated that as of December 29, 2022 that both VHF and ADS-B Stations would be decommissioned in this area. This effectively means we lose this airspace previously considered ATS Surveillance (DLM Exempt). This area is now part of the NAT DLM which requires FANS CPDLC and ADS-C. Below you can see an approximate outline of where VHF is found over the NAT. 

As you can see the green shaded area which represents VHF Coverage approximates much of what we consider ATS Surveillance (DLM Exempt Airspace) including GOTA off the coast of Canada. 

More Efficient Flight Planning 

What does using a more efficient routing through the updated ATS Surveillance airspace instead of the northerly Blue Spruce Routings mean for non-datalink equipped operators? When using a generic G-V we saw 22 minutes time saved enroute and over 1100 pounds less fuel burned vs. using a northerly Blue Spruce Routing.  

ATS Surveillance Area Overlay 

In order to assist our non-datalink customers with flight planning, we have added an “ATS Surveillance Area” overlay option under the “Oceanic” section within the route plot layers. Below you can see a screenshot that highlights the ATS Surveillance Area overlay (area with green shading) which you can see selected in the Layers tab on the right. This screenshot also shows a visual comparison of a more efficient ATS Surveillance based routing (green routing) vs a northerly Blue Spruce Routing (blue routing) for a leg from KTEB to BIKF. 

We hope that this is helpful in saving non-datalink-equipped operators both time and fuel.  

We’re always committed to finding the best options for our customers, so if you have any questions on this or any NAT related inquiries, please don’t hesitate to call our Flight Operations Team at +1-410-266-2266 or email them at [email protected].

• The GOTA or Gander Oceanic Transition Area was created in 2013 via Canada AIC 31/13, due to the installation and expansion of Air Traffic Service Surveillance Systems including ADS-B, VHF and Radar. 
• Canada advised the decommissioning of ADS-B and VHF stations in Southern Greenland in 2022 via Canada AIC 15/22.

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