CMV conundrum
Hi All, quick question on converted met visibility (CMV). I'll use the LFPG (Paris DeGaulle) runway 08L VOR approach as an example....
CMV takes credit for lighting systems that make it easier to identify the runway environment. At night with high intensity approach and runway lighting the reported met vis can be multiplied by 2 and by day, by 1.5. If there is no approach lighting system (ALS) operating, (ALS out on the chart), the multiplier is 1. That is, there is no benefit to be gained by using CMV as the reported met vis is considered to be the same as an RVR.
So, considering the LFPG 08R VOR, if ATC report a met vis of 900m and you require an RVR of 1500m for the approach, and assuming all the high intensity lights are operating, if it were daytime you would have a CMV of 1350m and if it were night you would have a CMV of 1800m.
In this instance you could not pass your approach ban point if it is day, but you can if it is night as the CMV is greater than the required RVR.
My question is this. On the (non-customised) minima panel on the Jeppesen LFPG 08R VOR approach chart, under 'ALS out' it quotes a CMV of 2300m. If the ALS is 'out' the reported vis is equivalent to an RVR (multiplier is 1), so why quote a CMV minima of 2300m when the reported met vis would be required to also be 2300m? Why not just quote vis?
Thanks in advance.