MI is correct, just because you have a certain viz doesn't mean you will see the runway at a certain point. I once landed with RVRs of 300m and NSC!
However... You could apply the 3 x rule, and therefore 1000km viz would be around 0.6 miles, and maybe you'd get the runway at 1.5 - 2 miles. But that's a very general estimate. Also, depending on where your flying, you should appreciate the difference between RA and BARO alt, RA does not always represent height above airfield datum.