Narrative:

We were flying to brookings VFR there was patchy ground fog in the area. The AWOS was calling 1/2 mi visibility (1 mi required for IFR approach). Our WX certified agent informed us the runway was clear of fog. We could see the entire runway totally clear of fog we got a special VFR and landed after more research. It may have not been legal, ie, AWOS called it 1/2 mi visibility. As it was in a fog bank, what caused this is a lack of knowledge as to who can overrule the AWOS if it's obviously inaccurate (PIC or company ground people or no one). In this example can a PIC use his own observation if in VFR conditions or can a certified WX observer overrule the AWOS observation. Supplemental information from acn 184963: debated whether we could land with AWOS reporting 1/2 mi, but company observer reporting greater than 1 mi. Found out later that you have to go by AWOS unless company observer calls it OTS. My experience has been that AWOS is frequently unreliable.

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Original NASA ASRS Text

Title: COMMUTER LTT LANDED IN WX RPTED BY AWOS AS BEING BELOW ARPT VISUAL MINIMUMS FOR LNDG.

Narrative: WE WERE FLYING TO BROOKINGS VFR THERE WAS PATCHY GND FOG IN THE AREA. THE AWOS WAS CALLING 1/2 MI VISIBILITY (1 MI REQUIRED FOR IFR APCH). OUR WX CERTIFIED AGENT INFORMED US THE RWY WAS CLR OF FOG. WE COULD SEE THE ENTIRE RWY TOTALLY CLR OF FOG WE GOT A SPECIAL VFR AND LANDED AFTER MORE RESEARCH. IT MAY HAVE NOT BEEN LEGAL, IE, AWOS CALLED IT 1/2 MI VISIBILITY. AS IT WAS IN A FOG BANK, WHAT CAUSED THIS IS A LACK OF KNOWLEDGE AS TO WHO CAN OVERRULE THE AWOS IF IT'S OBVIOUSLY INACCURATE (PIC OR COMPANY GND PEOPLE OR NO ONE). IN THIS EXAMPLE CAN A PIC USE HIS OWN OBSERVATION IF IN VFR CONDITIONS OR CAN A CERTIFIED WX OBSERVER OVERRULE THE AWOS OBSERVATION. SUPPLEMENTAL INFO FROM ACN 184963: DEBATED WHETHER WE COULD LAND WITH AWOS RPTING 1/2 MI, BUT COMPANY OBSERVER RPTING GREATER THAN 1 MI. FOUND OUT LATER THAT YOU HAVE TO GO BY AWOS UNLESS COMPANY OBSERVER CALLS IT OTS. MY EXPERIENCE HAS BEEN THAT AWOS IS FREQUENTLY UNRELIABLE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.