Were you responding to me, ShotOne, or making a general point? If at me, the "system" must assume that lost comms is purely a technical issue of some description - hence the visual communications codes, for example. However, UK QRA is not there to intercept a potential threat just to watch it deliberately crash into something. Things changed after 9/11. I can assure you the "system" is pretty switched on. When we were conceiving the "system" we did consider such events.
If your post post was not to me, sorry for bothering you.