Why do ATC sometimes change your squawk, when on a Eurocontrol IFR flight plan?

I often wonder about that too. Sometimes one can do three-hour flights on a single squawk (like last week when we went from Madrid to Halmstad with a 425MN direct leg – 60 minutes – in between, the longest I can remember). And other times, the squawk changes three times in 30 minutes.

In German upper airspace they often get you to Squawk 1000 as their computers apparently pair your radar return with your Mode S data rather than your squawk. They can then re-allocate your squawk code.

It happens a lot when crossing the Alps too – they give you a new squawk to positively identify you before any routing instructions. I suspect the PPRuNe ATC forum is probably the best place to get an informed answer from a controller.

I believe it has to do with CCAMS — the Eurocontrol coordinated transponder code assignment system. Not all countries participate in it and when you switch from a participating member to a non participating member, you get a different squawk.

autorouter gets those CCAMS assignments and sends you an email with your transponder code (useless but hey, emails are free ). Until yesterday it even did that in flight when you got a reassignment but I turned that off because it’s even less useful than knowing it upfront…

I like this situation because then I use phrase “1234 is coming down” which I’ve picked up from airliners and that makes me feel like a big guy

You should say “1234 on the box”.

1234 is coming down

That’s especially cool when still on the ground and the control tower is actually above the aircraft

That’s especially cool when still on the ground and the control tower is actually above the aircraft

I use it only when in the air on the ground I simply readback squawk 1234

VFR returning to Inverness, below 2000’, I got 3 different squawks, and one “squawk ident” after making contact 15 miles out on May 1. That was in Class G with Mode S.

Yes, but that is UK with it’s totally dis-jointed ATC…