Are you talking about Planning Minima?
Since RVR is never reported in the TAF or forecast in both the TAF and TREND it is ok to us this method - infact a number of operators do already - with limitations that it can't be used to determine T/O minimums, CAT2 & 3 minmia Circling or when an RVR is reported.
Empty CRZ: That's not how it works! If you are planning a CAT3 approach you must use the Vis i.e 200M for CAT3A - so in the case you give you would need 2 alternates! As you say AMS is a CAT3 airport , so depending on the RWY you are planning to use you would need CAT 1 minmima which would allow you to use the conversion or vis if you wish.
Last edited by LYKA; 24th March 2005 at 09:50.