Methinks that pilot assessment can only replace visibility, not rvr, althought i cannot find info in EASA doc.
IMHO it is an absolute necessity when rvr is not available due to the fact that observations from the tower is much more limited than looking down a lit runway.
As far as i remember, 60 meters are standard between runway edge lights.
Last edited by Flap Sup; 6th Sep 2014 at 13:53.