Originally Posted by
jmmoric
No, that is still not the case.
There's still the:
"Issue such ATC clearances as are necessary to prevent collisions and to expedite and maintain an orderly flow of air traffic."
So if you can see traffic, or have known traffic, you still have to make sure they do not collide. Like Chevvron says, 5 nm should be good enough.
You could argue that the required vertical/lateral separation minima does not apply, and you can go a bit closer, depending on the situation. But you'll still be held responsible if you let two known aircraft collide without acting.... Class E airspace will allow you to turn an IFR flight in this case.
5nm is the ICAO recommended minima; can be reduced to 3nm if both aircraft are identified and working the same radar unit.
In class A airspace the vertical separation minima against unknowns in the UK is 5,000ft, but that's not important right now.