Originally Posted by
Gertrude the Wombat
Traffic above Cambridge could be at any height if they're practising holds.
But it's class G, so you don't need permission. Talk to them, and if there's a problem they might politely ask if you mind sticking to your current altitude so they know what you're doing and can keep the instrument traffic out of the way, that's the most likely outcome. You don't need to talk to Duxford until you're clear of Cambridge.
Thanks for this. I’ll probably just fly overhead Cambridge any way. I was more just curious about what height you can safely assume an instrument track isn’t going to be an issue. I guess in every scenario you should be talking to them any way.