Well, separation is always required
I know what
you mean bfisk, and yes aeroplanes mustn't get too close to each other.
But please note - when discussing ATC and airspace classes, the term
separation carries a very precise meaning. In context,
separation is not always required. It is not required in any airspace Class F or G, and it is only sometimes required in classes C to E.
Chees,
O8