SMA STARTING TOUCH AND GO'S AT ARPT CALLS ON CTAF AND LEARNS THAT A TEMPORARY TWR IS IN OP ON A REGULAR BASIS.

Narrative

I WAS CONDUCTING A DAY VFR FLT WITH MY STUDENT IN THE VICINITY OF TRACY; CA. WE DECIDED TO DO A FEW LNDGS AT TRACY WHICH IS AN UNCTLED ARPT. WE CALLED 2 MI OUT AND ANNOUNCED WE WILL CIRCLE OVERHEAD. AT APPROX XX40 AM ON MAR/SAT/93; WE ANNOUNCED OUR POS; CIRCLING OVERHEAD AT 2500 FT MSL OVER UNICOM FREQ 122.8. WE WERE ADVISED TO CONTACT TRACY TWR AT THIS TIME ON 122.1. WE CALLED TRACY TWR AND RPTED OUR POS AT 2500 FT MSL OVERHEAD AND ASKED WHEN THEY BECAME A TWR'ED ARPT. TWR TOLD US TO RPT L BASE FOR RWY 29 AND STATED THE AIR NATIONAL GUARD OPERATES A TEMPORARY TWR AT TRACY ARPT THE FIRST WKEND OF EVERY MONTH. THERE WERE NO CONFLICTS WITH OTHER TFC OR WITH THE TEMPORARY TRACY TWR. CALLBACK CONVERSATION WITH FSS REVEALED THE FOLLOWING: CALL TO FSS REVEALED THAT A NOTAM IS SENT WHEN THE TEMPORARY TWR IS IN OP. IT IS A LCL NOTAM THAT REMAINS WITHIN THE FSS'S AREA OF JURISDICTION. THE ARPT IS LOCATED CLOSE TO THE BOUNDARY LINE FOR AN ADJACENT FSS. THE ARPT IS USED OFTEN BY PLTS IN THE ADJACENT FSS AREA OF JURISDICTION; AND AS A RESULT; MAY NOT KNOW ABOUT THE NOTAM.