Maybe I am just pedantic. According my company procedure I cannot fly a CAT 2/3 approach, unless low visibility procedures are in force. ( I assume it’s not only signal protection but also other precaution measures)
As far as I understand in JFK they only put them in force below RVR 1200. Above 1200 RVR they somehow protect the signal. But what’s the difference? Why don’t they apply low visibility procedures as soon as the weather gets below CAT 1 minima?