Hey Barney
Guess what? I talked to a friend of mine who still flies fast jets for the French Air Force. We are imagining that the corridor that you mentioned is the ARBOIS corridor. This is used for day and night training of Mirage pilots out of Dijon Longvic. In fact, it is basically the same as when I did my squadron training ahem,,, a few years ago.
It is active every weekday, and operations start at 09:30 local and stop at 17:00 local. Then they start again at sunset, and continue until midnight local.
On Wednesdays, they are only active until 14:30.
Training in the corridors whose upper limit is 2700 ASFC is currently very intensive. You may notice also, that many of the corridors also have assocaited stubs down to the surface from 800 ASFC.
Be careful out there. It sounds like some more pre-flight planning would perhaps be helpful for you.
Very happy to help you if you want it for a future trip.