captainsmiffy:
...the point raised, though, was that the rwy was not in fog. Only the transmissometer was...the question is about the legality of the approach when common sense points out the shortcomings of the rules. .
That is a very unusual condition. Even when it exists how does the flight crew safety and positively assess it; i.e., transmissometer(s) "fogged in" but the runway is "CAVU?"