Question: when are lvps in force?
Answer: LVPS; INITIATION BY ATC will initiate LVPs when the Touchdown Instrumented Runway Visual Range (IRVR) or the reported met Visibility indicates between 600m & 1000m, and is likely to continue to deteriorate. Cloud:- ATC will initiate LVPs when the Cloud Ceiling falls to 300ft, and is likely to reduce further.