David Reinhart wrote:

That's a contentious point that I don't know has been settled yet, though I think
the rulings so far are leaning the way you describe.

Since the ASOS/AWOS is usually not located at the end of a runway (I think they
try for a spot close to airport center) and airports are pretty large pieces of
real estate, it's entirely possible for the system to be reporting visibility
different from what the pilot is seeing from the air on approach. I think what
will certainly cause the FAA to jump on you is if an RVR is installed for the
runway you used and it was reporting visibility less than minimums.


At my airport it is common to get a fog bank over the eastern half of
the airport, the half that includes the ASOS. The western half will be
CAVU, which includes the full length of the small runway I normally use.
There I sit in the full sun unable to get a clearance for takeoff.