AN F28 CREW; DSNDING INTO SYR; RECEIVED A GPWS WARNING; 'TOO LOW TERRAIN' WITH A 'PULL UP' COMMAND.

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ON DSCNT INTO SYR; RWY 28 VECTOR; CLRED TO MAINTAIN 3600 FT MSL. MODERATE RIME ICING WAS ENCOUNTERED GOING THROUGH APPROX 5500 FT MSL. AT 4500 FT MSL; WE RECEIVED A 'TERRAIN' GND PROX WARNING AND 'PULL UP.' BY 4300 FT; WE WERE TRANSITIONED TO A GPWS ESCAPE MANEUVER. THE WARNING CONTINUED UNTIL WE HAD CLBED TO 7000 FT MSL; AND WERE CERTAIN THAT WE WERE WELL ABOVE ANY LCL TERRAIN. AT THAT POINT; I ASKED THE PNF TO DEACTIVATE THE AURAL WARNING AND NOTIFY APCH CTL OF THE SIT. WE THEN CONTINUED THE APCH TO A NORMAL LNDG. AT THE BEGINNING OF THE CLB FROM 4300 FT; I WAS ABLE TO VERIFY THAT MY ALTIMETER WAS CORRECTLY SET AT 30.08 INCHES AND THAT THE FO'S ALTIMETER CORRESPONDED TO MINE. I ALSO NOTED THE RADIO ALTIMETER INDICATING 410 FT AGL. DURING THE SUBSEQUENT NORMAL APCH; THE CTLR STATED THAT OTHER ACFT HAD EXPERIENCED SIMILAR CIRCUMSTANCES IN THE SAME AREA. INITIALLY I SUSPECTED A PROB WITH ONE OR BOTH RADAR ALTIMETERS; BUT THE SAME ACFT FUNCTIONED NORMALLY BEFORE AND AFTER THIS FLT. APPARENTLY; THE COMBINATION OF GPWS SYS AND THE FLT PATH IN THIS GEOGRAPHICAL POINT PRODUCED THE SPURIOUS WARNING. MAYBE IT SHOULD BE NOTED TO AIRMEN IN SOME APPROPRIATE MANNER. SUPPLEMENTAL INFO FROM ACN 528568: AT APPROX 4500 FT WE RECEIVED A GPWS WARNING (AURAL/VISUAL) TOO LOW TERRAIN. BY 4300 FT; WE WERE CLBING IN COMPLIANCE WITH ALERTS: RA 4100 FT WITH INTERMITTENT 1100 FT RA. THE CAPT CONTINUED CLBING AS I CONTACTED ATC TO STATE OUR INTENTIONS; REQUIRED A HIGHER ALT AND VECTORS TO COMPLY WITH GPWS WHICH CONTINUED TILL WE WENT ON TOP AT 7300 FT AND I DISABLED THE ALERTS.