1.) VMC or not; usually the crew will request a visual approach when the runway is "clearly" visible, and with ground contact accordingly (some "home" pilots occasionally overrule this), and EU-OPS require RVR800m or more (Visual approach. An operator shall not use an RVR of less than 800m for a visual approach.)
2.) a quick copy-paste from Doc. 4444, Chapter 6.,
6.5.3.5
For successive visual approaches, radar or non-radar separation shall be maintained until the pilot of a succeeding aircraft reports having the preceding aircraft in sight. The aircraft shall then be instructed to follow and maintain own separation from the preceding aircraft. When both aircraft are of a heavy wake turbulence category, or the preceding aircraft is of a heavier wake turbulence category than the following, and the distance between the aircraft is less than the appropriate wake turbulence minimum, the controller
shall issue a caution of possible wake turbulence. The pilot-in-command of the aircraft concerned shall be responsible for ensuring that the spacing from a preceding aircraft of a heavier wake turbulence category is acceptable. If it is determined that additional spacing is required, the flight crew shall inform the
ATC unit accordingly, stating their requirements.
Last edited by UpperATC; 1st Jul 2013 at 19:13.