Originally Posted by
terrain safe
It doesn't matter what flight rules the aircraft is flying under, wake turbulence separation is required at all times, either by informing the pilot or the ATCO providing the separation.
It is not separation with vfr.
The phraseology is 'caution wake turbulence,
recommended spacing is xxnm'.
The controller is neither providing or guaranteeing that distance, it is up to the pilot to assess how much spacing is needed. Further more the distance is recommended, not mandatory so the pilot may choose to fly closer or further behind.
Going back to the OP, there is no separation provided between IFR and VFR flights in Class D airspace. The use of the word 'following' here is misleading. If you are talking about an approach scenario then wake turbulence separation would be required regardless of flight rules. If you are talking more generally then it would be very hard to guarantee a certain distance behind a VFR aircraft that would not be flying vectors etc. Its not something I have ever seen but the IFR traffic would expect WT separation.