Oh dear. Another big hole in the cheese there.
Does anyone have a reference to the UK version of the
manual that Easy Street referenced ? I know from memory that the London controllers will not allow visual separation unless BOTH aircraft involved accept it. In London this is only applicable in the case of helicopter traffic crossing in opposite directions on a route, and is negotiated between the crossing helicopters by ATC on a specific case by case basis as a precondition of entry to the routes.
This makes sense. Why should you be put in a situation where another aircraft is responsible for your safety ?