"Jon O'Rourke" wrote in message
...
Phil, remind me, do LVPs come into force from the beginning of the period
of
a fog warning or are they governed by current conditions alone ?

LVPs come into force when the RVR is 600m or cloud ceiling 200ft or less.
That said, Traffic Managers do sometimes apply a regulation on the basis of
a forecast :-) which can bring delays even if LVPs do not materialise.
Fog warnings per se are not really useful to us, as they do not recognise
the LVP criteria (as they are looking for a vis less than 1000m? but no
reference to cloud) and they often arrive after the fog has formed - but
we'll put that down to the AFTN :-)


Phil