A C182 EQUIPPED WITH EFIS-FMC ENTERED THE PATTERN AT GLS WITHOUT TALKING TO THE TWR BECAUSE THEIR NAV SYS SHOWED THE ARPT WAS UNCTLED.

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MY HUSBAND AND I DECIDED TO GO FLYING IN OUR C182. WE DEPARTED LBX (BRAZORIA COUNTY; TX) AT XA00 LCL. THE CESSNA IS A 2004 MODEL WITH AN AVIONICS PACKAGE THAT WE HAD HAD SOME SUBSTANTIAL MAINT ISSUES WITH. DURING OUR FLT WE DECIDED THAT IT WAS A NICE EVENING AND WE SHOULD GO TO GALVESTON FOR DINNER. I WAS CONCERNED ABOUT A FOG BANK THAT WAS DEVELOPING OVER THE WATER AND SO WE CHKED FOR FORECASTS FOR GLS AND BRAZORIA COUNTY WITH OUR ONBOARD SATELLITE SYS. THE FORECAST WX LOOKED GOOD AND WE DECIDED TO CONTINUE TO GLS. MY HUSBAND DOES NOT YET HAVE HIS PVT LICENSE AND WAS TALKING ON THE RADIO. WE BEGAN NORMAL BROADCASTS ON UNICOM 10 MI W OF GLS; UNAWARE THAT A CTL TWR WAS NOW OPERATIONAL THERE. WE THOUGHT IT WAS ODD THAT NO ONE CAME BACK WITH AN ARPT ADVISORY BUT CONTINUED WITH NORMAL BROADCASTS; LOOKED AT THE WINDSOCK AND ENTERED A DOWNWIND FOR RWY 13. WE SAW A MOONEY WAITING FOR TKOF AND ALSO THOUGHT IT WAS A LITTLE STRANGE THAT HE WAS NOT TALKING ON THE RADIO BUT ONCE AGAIN IT IS NOT ALL THAT UNCOMMON FOR UNCTLED ARPTS. OUR BELIEF THAT GLS WAS UNCTLED WAS SUPPORTED BY THE FACT THAT THE G-1000 SHOWED THE ARPT AS MAGENTA AND DID NOT SHOW A TWR FREQ. WHILE WE WERE ON A HIGH FINAL; THE MOONEY PULLED OUT ONTO THE RWY FOR TKOF AND WE ELECTED TO GO AROUND. WE REMAINED OFFSET TO THE W SO WE COULD WATCH THE MOONEY'S DEP PATH. AT THIS TIME WE ALSO SAW 2 HELIS IN THE PATTERN AND THEN SOMEONE CAME UP ON UNICOM AND TOLD US TO CONTACT TWR. THIS; OF COURSE; WAS HEART-STOPPING NEWS; BUT WE CONTACTED THE TWR AND THEN OBTAINED A PHONE NUMBER FOR LATER CONTACT. OF COURSE; AFTER ANY INCIDENT; THERE IS MUCH REVIEW AS TO WHY THIS HAPPENED AND IT WAS A VALUABLE LEARNING EXPERIENCE FOR BOTH OF US. MOST OF OUR GA FLYING IS DONE IN A J-3 CUB; AND WE ARE ACCUSTOMED TO KEEPING OUR EYES OPEN. BUT IN THIS CASE; WE RELIED ON OUR AUTOMATION AND THE FACT THAT WE HAVE ALWAYS KNOWN GLS TO BE UNCTLED. AS IT TURNS OUT; EVEN THOUGH WE HAD BEEN UPDATING OUR AVIONICS SYS AND THE AIRPLANE HAD IN FACT JUST COME OUT OF ANNUAL WHERE THEY UPDATED EVERYTHING; THE UPDATE THAT SHOWS ON STARTUP WAS PRIOR TO THE INSTALLATION OF THE CTL TWR AT GLS. WE ARE NOW IN THE PROCESS OF FINDING OUT WHY; EVEN THOUGH THE UPDATES APPEARED TO 'TAKE;' THEY DID NOT. WE DO CARRY A SET OF CURRENT CHARTS IN THE AIRPLANE; HOWEVER ON THAT PARTICULAR DAY; WE BELIEVED WE HAD ALL THE RELEVANT INFO WE NEEDED AND CHOSE NOT TO PULL THEM OUT. IN THE FUTURE; OUR PLANNING WILL BE MORE THOROUGH.