A question,

I recently stumbled on the fact that Spain, France and Belgium operate the North-South rule for IFR RSVM flight levels while The Netherlands etc employ the East-West configuration.

So when you transit the airspace between those countries, (let's say heading northeast from the Belgian coast heading into Netherlands) are you expected to be at the new FL at the transition/ border waypoint or after it? What does ATC normally instruct you to do?

3 hours ago, 787flyer said:

A question,

I recently stumbled on the fact that Spain, France and Belgium operate the North-South rule for IFR RSVM flight levels while The Netherlands etc employ the East-West configuration.

So when you transit the airspace between those countries, (let's say heading northeast from the Belgian coast heading into Netherlands) are you expected to be at the new FL at the transition/ border waypoint or after it? What does ATC normally instruct you to do?

Very good question and short answer.

You don't independently change your cruising level merely because you cross the national/FIR boundary. The level change is made according to the clearance/transfer/handoff arrangement between ATC units, and is normally coordinated so that you enter the next area at the appropriate level.

 

This EUROCONTROL structure differs in certain respects and uses different semicircular allocations, requiring a level change for traffic entering the next area. Operationally, it's quite interesting to see in upper European airspace that the controlling sectors frequently don't correspond to national boundaries. Maastricht UAC, for example, controls upper airspace over Belgium, Luxembourg, the Netherlands and northwest Germany, and its sector boundaries are designed around traffic flows rather than national borders. Normally, for a normal European overflight, the level change is often handled almost invisibly to the crew because it has already been coordinated between sectors. 

Just to remember, you fly the cleared level, not the level you calculate from the new country's semicircular rule. You do not climb on your own; you remain at your assigned FL until ATC clears the change.

Got it!

Many thanks for that information. Most helpful and much appreciated.

Cheers
Mark

9 hours ago, 787flyer said:

I recently stumbled on the fact that Spain, France and Belgium operate the North-South rule for IFR RSVM flight levels while The Netherlands etc employ the East-West configuration.

Pretty sure Belgium uses conventional RVSM levels?
The unconventional FIRs in Europe are LP, LE (including canarias) , LI and LF + LS (both above FL195)

On 8/22/2026 at 9:14 PM, SAS443 said:

Pretty sure Belgium uses conventional RVSM levels?
The unconventional FIRs in Europe are LP, LE (including canarias) , LI and LF + LS (both above FL195)

Thanks. Yes you are correct. I thought I had seen a reference to Belgium and Italy opearting the same rules but I can not seem to find that reference now and so not sure whether that was a bonafide source or not I was remembering.

Found this Eurocontrol chart that shows the different semi circular rules in place across Europe.

Eurocontrol chart