Purr you wrote:
It is all pretty straight forward you get icing when the TAT is 10 centigrade or less plus the viz has to be one mile or less.
Are you sure the viz has to be less than 1 mile. Is this in your SOPs? As I have yet to see it written in a Text Book.
So if I have 1.2 Miles Viz, I am ok am I?
Regards
Sheep
P.S. As I said previous, there are no hard and fast rules with weather. You cant afford to be too definative as people, will take you literally!