FLC OF MLG ACR ACFT TOOK EVASIVE ACTION IN RESPONSE TO THE ACFT GND PROX WARNING ALERT DURING A VISUAL APCH.

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AT APPROX XA15L WE WERE OPERATING ON APCH CTL VECTORS FOR A VISUAL APCH TO BDL ARPT. WE WERE UNDER AN OVCST; IN VFR CONDITIONS; XING BTWN THE RIDGE LINES APPROX 15 NM NW OF BDL. THE ARPT WAS IN SIGHT; AND WE WERE JUST ABOUT LINED UP WITH RWY 15. WE HAD BEEN CLRED TO DSND TO 3000 FT (APCH CTL'S MVA). AT APPROX 3500-3700 FT MSL WE GOT A GND PROX WARNING TERRAIN; FOLLOWED SHORTLY BY A PULL UP. AN IMMEDIATE CLB WAS STARTED IAW REGS. THE GND PROX WARNING CONTINUED THROUGH ABOUT 4200-4500 FT MSL. ABOUT THAT TIME APCH CTL CALLED QUESTIONING OUR CLB. HE STATED THAT THERE WERE NO TFC CONFLICTS; AND RECLRED US FOR APCH TO RWY 24 BECAUSE OF THE ALT. I CALLED HIM AFTER LNDG AND HE INDICATED THAT HE HAD NO PROBS WITH OUR ACTIONS AS THERE WERE NO TFC CONFLICTS. HE ALSO TOLD ME THAT HIS MVA IN THAT AREA IS 3000 FT; SO WE WERE WELL ABOVE THE TERRAIN. I RECHKED OUR ALTIMETER SETTINGS AND BOTH WERE CORRECT. I HAVE FLOWN THIS PARTICULAR APCH MANY TIMES IN THE PAST WITH NO PRIOR PROBS. I TALKED TO A MECH AFTER LNDG AND HE INDICATED THAT SEVERAL ACFT HAVE RPTED A SIMILAR EXPERIENCE RECENTLY. HE COULD OFFER NO SUGGESTIONS AS TO CAUSE; BUT DID HYPOTHESIZE THAT A SKI AREA NEAR THE POINT OF OCCURRENCE HAS A SNOW MAKER THAT MAY CAUSE THE RADIO ALTIMETER TO TRIGGER.