5'n'3:
If an unknown aircraft chooses to operate in the vicinity of one of the approaches to Norwich at the same time that a passenger flight is trying to make an approach to land then that aircraft simply cannot make the approach
Really? So how does it go then: "Jersey 1234 turn right heading 060 routing you to the hold due to unknown traffic at 6nm on the 09 approach"? Or "Jersey 1234 radar service terminated due to unknown traffic on the approach" "Roger in that case we're diverting to Stansted"?
Or is it more like "Jersey 1234 unknown traffic in your 12 o'clock range 6 miles no height information, unable to continue with deconfliction service are you happy to continue against that traffic on a Traffic Service?", with the Flybe then making a decision based on his in-flight conditions, or possibly asking for the reciprocal runway if wind permits?
If it's clear from the unknown radar returns that this is a manoeuvring fast jet then the controller's options will be much more limited - but then again any FJ ought to be squawking so there will be height info too, and the squawk will indicate who (if anyone) he is talking to.
NS