Visibility for Minima-measurement n evaluation
Dear Aviators,
I wish to consult the learned ones for opinions on a few issues on the visibility criteria for landing minimum. Let's talk about typical Cat 1 minima for discussion; 200' and 800m vis. Many that I know take visibility as the number 1 weather criteria (with the deceleration accounted for) in their day to day operations.
1. I have heard that some aviators translate visibility to height above which you are expected to see the runway, by using the 1/60 rule and some conversions- ie you are expected to see the runway with 1km visibility at 160', 2km at 330', 3km at 500'. This probably assumes no significant cloud at low level. This being the case, would visibility of 1km still good to conduct a Cat 1 appr?
2. It is argued by some that measurements of visibility is of static nature. This supposedly creates complication for weather condition with precipitation for pilots. That is when it is raining the 2km reported is not the same as a 2km without precipitation. I have heard of aviators who use a factor of half for interpretation of moderate precipitation-ie when it is reported 2km and using the method in point 1 you are expected to see the runway at 330/2=165'. The minima predicated on approach charts do not take this precipitation into account?
Any views or comments for the above mentioned techniques please?
Many thanks for sharing.