CL65 CREW EXECUTED AN EGPWS ESCAPE MANEUVER WITH AN EMER MAX RATE CLB UNTIL THE WARNING STOPPED. ACFT WAS ABOVE THE MINIMUM VECTORING ALT AT THE TIME OF OCCURRENCE.

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ON MAR/SUN/02; WHILE BEING VECTORED FOR AN APCH (ILS) TO RWY 13 AT MDT; HARRISBURG; PA; AT AN ALT OF 3000 FT MSL AND APPROX 13 NM NW OF THE FIELD ALONG THE EXTENDED CTRLINE OF APCH LOC; WE RECEIVED A GPWS WARNING 'TERRAIN; TERRAIN; PULL UP.' MY FO IMMEDIATELY DISCONNECTED THE AUTOPLT AND INITIATED A RAPID CLB. AT APPROX 3800 FT MSL; I NOTIFIED HARRISBURG APCH THAT ACR X; OUR FLT WAS CLBING DUE TO A TERRAIN WARNING. WE LEVELED THE ACFT OFF AT 4300 FT MSL. ATC ADVISED US THAT THE MINIMUM VECTORING ALT IN THAT AREA WAS 2600 FT MSL AND THAT WE SHOULDN'T HAVE RECEIVED A TERRAIN WARNING. SINCE WE WERE SO FAR OUT FROM THE ARPT; WE WERE RECLRED FOR THE ILS RWY 13 AT MDT. WE COMPLETED THE APCH AND LANDED. UPON TAXI INTO THE GATE; ATC CTLR (SAME ONE WHO WAS OPERATING APCH; TWR AND GND CTL) ADVISED US THAT WE MIGHT WANT TO HAVE OUR GPWS EQUIP CHKED FOR ERRORS. MY FO SIMPLY RESPONDED BY EXPLAINING TO THE CTLR THAT WE CANNOT SIMPLY IGNORE TERRAIN WARNINGS WHILE IMC. MY FO EXPLAINED THAT WE MUST CLB IMMEDIATELY WHEN WE RECEIVE SUCH WARNINGS WHILE IMC. AT THAT TIME; THE CTLR STATED THAT WE 'REALLY SHOULD'VE LET HIM KNOW BEFORE WE INITIATED THE CLB LIKE THAT.' HE THEN ADVISED US THAT WE (OR I; THE CAPT) NEEDED TO CONTACT THE TWR VIA TELEPHONE AFTER WE ARRIVE AT THE GATE. I GAVE THE CTLR MY CELL PHONE NUMBER AND HE CALLED ME ABOUT 5 MINS LATER. WE TALKED ABOUT THE SIT AND HE STATED THAT; HAD WE BEEN ON THE APCH FOR ILS RWY 13 10 MINS LATER; WE WOULD'VE HAD A CONFLICT WITH A CARAVAN OVERFLYING THE APCH CORRIDOR FOR ILS RWY 13 AT 4000 FT MSL. HE ASKED WHAT WE WOULD'VE DONE IN THAT SIT. I TOLD HIM THAT WE WOULD'VE HAD AN EVEN WORSE SIT BECAUSE OUR TCASII WOULD HAVE BEEN SCREAMING AT US ALSO. MY FO AND I COMPLIED WITH OUR PROCS FOR TERRAIN WARNINGS WHILE IMC AND DID OUR JOB PROPERLY. I QUESTION WHY WE WERE HARASSED ABOUT THE SIT. I PROPERLY NOTIFIED ATC OF THE CLB ASAP. ANOTHER QUESTION IS THIS; WHY WOULD A CTLR VECTOR AN ACFT ACROSS AN APCH CORRIDOR WHILE AN ACFT IS ON AN INST APCH? SUPPLEMENTAL INFO FROM ACN 540090: WHILE ON VECTORS FOR AN ILS APCH TO RWY 13 AT MDT RECEIVED 'TERRAIN; TERRAIN; WHOOP; WHOOP; PULL UP' IN IMC. IMMEDIATELY DISENGAGED AUTOPLT AND BEGAN A CLB AFTER WARNING WENT AWAY. I LEVELED OFF AT ABOUT 4300 FT MSL. BECAUSE OF OUR DISTANCE FROM THE FIELD THE CTLR CLRED US BACK DOWN TO 3000 FT AND FOR THE APCH. I THINK IT WAS AN ACFT ANOMALY; BUT BECAUSE OF OUR STANDARD OPERATING PROCS I WAS FORCED TO CLB TO A 'SAFE ALT.'