It works because one assumes that if one is performing a visual cct in 800m RVR:-
1) You are either good or stupid.
2) If you can see to do the cct, what is wrong with a g/a to another? If you cannot see to do the cct.....................wtf are you there?
3) You are not 'circling'
Who said anything about flying a visual circuit. It could be a visual straight-in approach.
Just because the airport is reporting an RVR of 800m it does not mean that during the approach you can not be in VMC and visual all the way to touchdown.
Dead right we are not circling, circling requires a
visibility of 2400m in a CAT C aircraft but if we can satisfy the requirements we can make a visual approach in something less than that.
Imagine Instrument approach is an ILS to 27 but the wind favours 09 which has no approach procedure. You are approching from the west and there is some sea harr to the east partially encroaching on the aerodrome. The RVR is 1400m - good enough to
a) complete a straight-in ILS
or
b) a visual straight-in 09 -
if you can satisfy the requirements for a visual approach
but
not a circling approach !!
So what do you do if you have to make a missed approach at 100ft on final 09?
I will say it again - visual approach is one where it is made up of random parts - nothing prevents it being briefed. There is no defined missed approach so it would be good practice to find out and brief in advance what all the team expects. By team I mean ATC as well as your nearest colleague.