The Automatic Enroute Information Service broadcasts what forecasts and on what frequency band?
METAR/SPECI an TAF
VHF
A report on the visibility in the touchdown and midpoint zones of a runway, assessed by a ground observer counting visible runway lights or visibility markers
RV - Runway Visibility
Automatic displays to ATC unit of the visibility by transmissometers representative of the touchdown, midpoint and rollout/stop end zones
RVR - Runway Visual Range
What are the minimum forecasts to be studied?