GPWS ALERT DURING A NIGHT OP SENDS AN SF340 INTO A CLB. ALTDEV ALT EXCURSION. PIC ASKED TO CALL SUPVR WHEN APCH CTLR NOT AWARE OF WHAT THE PROB WAS.

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WE WERE DSNDING FROM INTERMEDIATE ALT TO LEVELOFF AT 2100 FT AND TURNING FOR FINAL VECTOR TO INTERCEPT LOC RWY 10 AT SYR. JUST PRIOR TO LEVELOFF; THE GPWS TERRAIN WARNING WAS ACTIVATED. CREW TOOK IMMEDIATE CORRECTIVE ACTION AND INITIATED A CLB. (NO OTHER ACFT WERE NOTED ON OUR OPERATIONAL TCASII IN THE VICINITY. APCH HADN'T INFORMED US OF ANY ACFT TO BE CONCERNED WITH.) NOTIFIED APCH THAT WE WERE CLBING. WARNING ENDED AT ABOUT 2500-2600 FT. CTLR DIDN'T APPARENTLY UNDERSTAND WHAT WAS GOING ON; SO WE SPELLED IT OUT TO HIM THAT WE HAD A GPWS ALERT AND WE HAD TO CLB. CTLR WANTED US TO CALL HIS SUPVR. I CALLED AND TALKED TO A MR X. HE SAID THAT HE HAD TO FILL OUT A RPT ON THE INCIDENT SO IT COULD BE PREVENTED IN THE FUTURE; BECAUSE HE WAS CONCERNED ABOUT CONFLICTING TFC. HE THOUGHT THAT THERE MIGHT HAVE BEEN SOMETHING WRONG WITH OUR GPWS. I EXPLAINED TO HIM THAT I WAS NEW TO THE AIRPLANE BUT WAS FAMILIAR WITH GPWS OPS; BUT NEVER HAD ANYTHING LIKE THIS. I FELT THAT THE WARNING COULD HAVE BEEN TRIGGERED BY A 900 FT ANTENNA OR OUR RATE OF DSCNT. SYS WAS OPS CHKED NORMAL PRIOR TO TKOF AND NO ABNORMAL INDICATIONS NOTED DURING OUR FLT OR ANY PREVIOUS WRITE- UPS. I CAN'T THINK OF ANYTHING THAT WE COULD HAVE DONE DIFFERENTLY. IF THERE WAS CLOSE TFC; APCH (USUALLY) WOULD HAVE INFORMED US. WE WERE IN SEMI VFR CONDITIONS AND HAD GOOD INFLT VISIBILITY. NO TCASII CONFLICT WAS OBSERVED EITHER. I AM NOT GOING TO FLY INTO TERRA FIRMA WHILE I AM TRYING TO TROUBLESHOOT THE GPWS WARNING SO NOT TO UPSET A CTLR.