Formidable Shield 2021: NAT Airspace Closures

By David Mumford


Remember that big NAT military exercise a couple of years ago? Formidable Shield is happening again this year, from May 18 to June 4, which will mean large parts of North Atlantic airspace will be closed to all flights for several hours at a time.

Deep in the bowels of the Eurocontrol website they have published this doc which tells you all about it. Here’s the lowdown:

EGDFS21A1 (a.k.a The Big Area)
Closed on May 24, 26, 28, 30 and either June 1 or 2 daily 1400-2100z. This will have a big impact to trans-Atlantic flights, particularly those on the westbound NAT Tracks (valid from 1130-1900z daily).

EGDFS21A2 (a.k.a. The Wing-Shaped Area)
Closed on May 26, 28, 30 and either June 1 or 2 daily 1400-2100z.

EGD701 (a.k.a The Little Area)
This area is tricksy, because it’s made up of several little chunks of airspace that all close at different times. But ultimately, the whole thing is closed from May 19 – June 4 daily 1300-2100z (it may close earlier than 1300z some days for preparation activities, but if this happens then most of the time it will only be closed up to FL270).

Here’s a map showing the several little chunks of airspace that make up this area:

And here’s the mind-boggling plan for which sections will close at different times:

So ultimately, there are three chunks which will be closed for the entire duration: D701A, D701B and D701D. These ones:

At the moment, all of this is academic – the real schedule will be published by Notam at least 24 hours in advance. When each of these sections of airspace is closing, they will publish a Notam referencing the specific airspace code: EGD701, EGDFS21A1, or EGDFS21A2. If you try to file a flight plan through one of the closed areas, it will get rejected.

Routing around the closed airspace

Prestwick Area Control Centre will issue an Aeronautical Information Message (AIM) prior to the start of the exercise, which will include suggested routings for flight planning around the closed areas. The nearest available points to the north will be ATSIX and to the south will be DINIM.

The UK AIP SUP 11/2021 says that overflying traffic heading around these closed areas will get 30NM separation if in NAT HLA airspace (FL285-420), or 60NM separation if flying at lower levels.

For any questions on Formidable Shield, you can contact the UK Airspace Management Cell at


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David Mumford

David Mumford

OPSGROUP Helmsman of the B's: Blog, Bulletin, and Briefs. Question for us? Write to

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