reducing "Crew-caused"
approach and landing

Pilot-in-charge Monitored Approach

Minimum RVR's purpose.

The only real function of RVR is to control the approach success rate for a given decision height. By using it for this purpose, we are suggesting that a relationship exists between the RVR and the visual reference that will be available at the decision height.  As we saw earlier this relationship is, to say the least, vague — but we have to use RVR because it's the only suitable parameter we have. An RVR of 600m can yield an SVR between 250m and 800m, and the only way to determine exactly what will be available is to fly an aeroplane down to decision height and have a look.

The fact that the RVR is at or above limits in no way obliges a pilot to attempt a landing in these conditions — it merely allows him to make an approach and judge for himself the visual conditions. The decision to land is made by the pilot, not by the RVR.  The RVR value is, therefore, best regarded only as the means of determining whether or not an approach ban exists. The accurate regular and frequent RVR reporting required for this purpose will at the same time provide a good indication of conditions on the runway in the touchdown zone for landing aircraft. 
Neither the transmissometers, nor any other practical method of RVR measurement using a number of sensors away from the runway, can hope to provide a pilot with completely accurate information as to what visual range will be available to him above and along the runway. Additionally, no means have been found to forecast with precision RVR changes for even ten minutes ahead.
This is why Captains are required to assess the visual conditions themselves before reaching decision height.