Narrative:

During my emb-120 brazilia transition first officer check ride, we may have been flying in the pattern with less than 3 mi visibility being reported on AWOS WX service. At no time was the in-flight visibility actually that low. However, light ground fog was beginning to form, not so much on the runway, but to the east and surrounding areas. Seeing the formation of ground fog as we taxied to the departure end of the runway I requested the check airman to check the WX. At this time AWOS was calling visibility 1 mi. We both were very surprised. We could see the entire length of the runway as well as lights greater than 3 mi. Within 15 mins after the check was made, the ground fog became much more apparent. After becoming aware of the visibility IFR clrncs were used. I had completed all portions of the check ride in the simulator that night and needed to fly the actual aircraft that night for takeoffs and lndgs. I had a lot on my mind during the check ride but WX conditions remained a priority. It is my feeling that in this case AWOS readings did not represent actual runway and airport conditions during a brief time of the ground fog formation.

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Original NASA ASRS Text

Title: FLC OF AN LTT ACR ACFT INADVERTENTLY MADE TKOFS AND LNDGS IN A CTL ZONE TFC PATTERN ARPT WITHOUT AN IFR CLRNC.

Narrative: DURING MY EMB-120 BRAZILIA TRANSITION FO CHK RIDE, WE MAY HAVE BEEN FLYING IN THE PATTERN WITH LESS THAN 3 MI VISIBILITY BEING RPTED ON AWOS WX SVC. AT NO TIME WAS THE INFLT VISIBILITY ACTUALLY THAT LOW. HOWEVER, LIGHT GND FOG WAS BEGINNING TO FORM, NOT SO MUCH ON THE RWY, BUT TO THE E AND SURROUNDING AREAS. SEEING THE FORMATION OF GND FOG AS WE TAXIED TO THE DEP END OF THE RWY I REQUESTED THE CHK AIRMAN TO CHK THE WX. AT THIS TIME AWOS WAS CALLING VISIBILITY 1 MI. WE BOTH WERE VERY SURPRISED. WE COULD SEE THE ENTIRE LENGTH OF THE RWY AS WELL AS LIGHTS GREATER THAN 3 MI. WITHIN 15 MINS AFTER THE CHK WAS MADE, THE GND FOG BECAME MUCH MORE APPARENT. AFTER BECOMING AWARE OF THE VISIBILITY IFR CLRNCS WERE USED. I HAD COMPLETED ALL PORTIONS OF THE CHK RIDE IN THE SIMULATOR THAT NIGHT AND NEEDED TO FLY THE ACTUAL ACFT THAT NIGHT FOR TKOFS AND LNDGS. I HAD A LOT ON MY MIND DURING THE CHK RIDE BUT WX CONDITIONS REMAINED A PRIORITY. IT IS MY FEELING THAT IN THIS CASE AWOS READINGS DID NOT REPRESENT ACTUAL RWY AND ARPT CONDITIONS DURING A BRIEF TIME OF THE GND FOG FORMATION.

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.