Narrative:

The galveston airport (gls) where my aircraft is based is a non-controled airport with ASOS and a unicom TA frequency. I had checked the WX using duats, but missed the NOTAM that indicated there was a temporary tower established friday (day of flight) through sunday, due to a function that was expected to draw additional traffic over the weekend. I was not aware of this, so taxied out and took off making normal TA's on the unicom frequency. I was just going around the pattern once to warm the oil in preparation for an oil change. When making my turn to base, the unicom operation advised me that there was a temporary tower in use and gave me the frequency. I called the tower and reported my position, and was cleared to land. No other traffic was in the area. This was not a widely advertised temporary tower, and nothing was noted, to my recollection on the ASOS, which would have alerted me of the change.

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Original NASA ASRS Text

Title: RWY INCURSION AND UNAUTH TKOF BY A C310 ATP PLT WHEN HE FAILS TO READ THE NOTAM INSTALLING A TEMPORARY TWR FOR THE WEEKEND AT GLS, TX.

Narrative: THE GALVESTON ARPT (GLS) WHERE MY ACFT IS BASED IS A NON-CTLED ARPT WITH ASOS AND A UNICOM TA FREQ. I HAD CHKED THE WX USING DUATS, BUT MISSED THE NOTAM THAT INDICATED THERE WAS A TEMPORARY TWR ESTABLISHED FRIDAY (DAY OF FLT) THROUGH SUNDAY, DUE TO A FUNCTION THAT WAS EXPECTED TO DRAW ADDITIONAL TFC OVER THE WEEKEND. I WAS NOT AWARE OF THIS, SO TAXIED OUT AND TOOK OFF MAKING NORMAL TA'S ON THE UNICOM FREQ. I WAS JUST GOING AROUND THE PATTERN ONCE TO WARM THE OIL IN PREPARATION FOR AN OIL CHANGE. WHEN MAKING MY TURN TO BASE, THE UNICOM OP ADVISED ME THAT THERE WAS A TEMPORARY TWR IN USE AND GAVE ME THE FREQ. I CALLED THE TWR AND RPTED MY POS, AND WAS CLRED TO LAND. NO OTHER TFC WAS IN THE AREA. THIS WAS NOT A WIDELY ADVERTISED TEMPORARY TWR, AND NOTHING WAS NOTED, TO MY RECOLLECTION ON THE ASOS, WHICH WOULD HAVE ALERTED ME OF THE CHANGE.

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.