ATCO 2:
<Any unidentified traffic is tracked on radar, and appropriate action taken.>
Which presumably means subsequent legal action against the pilot?
Not a lot of use if he has already crashed into a high-rise building or Buckingham Palace. This makes no sense to me and seems like a panic reaction by someone who doesn't understand the problem or has been told to "DO SOMETHING!" - so it has, for a nice tick in the box.
