RPTR EXPERIENCES GPWS WARNING DURING VISUAL TO RWY 9 AT STEWART ARPT (SWF).

Narrative

RPTED ARPT IN SIGHT AND WAS 'CLRED FOR A VISUAL TO RWY 9 AT SWF' WHEN APPROX 20 MI NW OF THE ARPT AT 4000 FT MSL. PLANNED TO BE AT NEELY; THE NDB FOR THE ILS; AT 2100 FT MSL (1600 FT AGL) INBOUND ON LOC AND GS. FLEW A HDG OF APPROX 140 DEGS TO INTERCEPT ILS JUST OUTSIDE OF NEELY. WHEN CLRED FOR A VISUAL; STARTED A DSCNT TO 3000 FT MSL AND PLANNED TO SLOW AND DSND SO AS TO BE AT 2100 FT WHEN INTERCEPTING THE LOC NEAR NEELY. AT APPROX 15 NM FROM THE ARPT WITH THE ARPT STILL CLRLY IN SIGHT; DSNDING THROUGH 3500 FT MSL; RECEIVED A GPWS WARNING 'TERRAIN; TERRAIN; WHOOP; WHOOP; PULL UP.' I PROMPTLY INITIATED A CLB BACK TO 4000 FT MSL. WARNING CEASED AND CTLR ALSO SAID '...YOU SHOULD MAINTAIN 4000 FT PRIOR TO RETURNING TO ALT.' CONTINUED TO ARPT UNEVENTFULLY WITH INITIAL DSCNT LATER THAN ORIGINALLY PLANNED. UPON ARR WE ASKED THE TWR CTLR ABOUT TERRAIN IN THE VICINITY OF THE WARNING AND WERE TOLD THAT A 2500 FT RIDGE WAS IN THAT LOCATION WITH HIGHER UNLIGHTED ANTENNAE. THE CTLR ALSO STATED THAT WHEN CLRED FOR A VISUAL WE 'COULD DSND AT OUR DISCRETION AS LONG AS THE ARPT WAS IN SIGHT' AND 'THE CTLR WAS DISCUSSING THE SIT WITH THE SUPVR.' AT THAT POINT A CREW MEMBER FROM ANOTHER ACR STATED ON FREQ 'WE HAD A PROB WITH THAT TOO.' WE HAD THE ARPT IN SIGHT PRIOR TO; DURING; AND AFTER THE WARNING AND THERE WERE NO INDICATIONS OF THE PRESENCE OF INTERVENING TERRAIN (DISTANT LIGHTS 'DISAPPEARING' BEHIND THE RIDGE; ETC). ADDITIONALLY; THERE WERE NO OBVIOUS INDICATIONS ON ANY OF OUR IFR CHARTS THAT A DSCNT FROM 4000 FT TO 3000 FT AT THAT POINT WOULD BE A PROB. THE FOLLOWING CONSIDERATIONS MIGHT HELP PREVENT THIS SIT FROM RECURRING: 1) ATC SHOULD NOT CLR ACFT FOR VISUAL APCHS AT SWF (PARTICULARLY AT NIGHT OR IN MARGINAL WX) UNTIL CLR OF THE RIDGE. (NOTE: IT COULD BE THAT THE NEW YORK APCH CTLR HAD NO KNOWLEDGE OF THE RIDGE; WHILE THE LCL CTLRS DID). 2) I WILL PLAN A 3:1 DSCNT PROFILE FOR ALL VISUAL APCHS AND SHOULD NOT HAVE DSNDED BELOW 4000 FT APCHING SWF UNTIL CLOSER TO THE ARPT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID HE WAS FLYING A FOKKER 100. THE NIGHT WAS CLR; VISIBILITY UNLIMITED; BUT IT WAS DARK. THE ARPT WAS CLRLY IN SIGHT WHEN HE RECEIVED THE CLRNC FOR THE VISUAL APCH. THE ONLY CHART REF IN FRONT OF HIM WAS THE ILS RWY 9 (ANALYST GRAPHIC 3). HE SAID THIS NIGHT WAS THE FIRST TIME FOR HIM INTO THE ARPT. SINCE THEN HE HAS APCHED STEWART IN THE DAYLIGHT TO BE AMAZED AT HOW THE RIDGES POKE UP. HE SAID THIS IS THE TYPICAL WAY NEW YORK APCH GUIDES AIRLINERS INTO STEWART FROM THE N ALONG AIRWAYS TO FILPS INTXN TO WHERE YOU HAVE TO CROSS THE RIDGE LINE TO GET TO THE ARPT AND THEN CLRS THE AIRLINER FOR THE VISUAL UPON DETERMINING THE ARPT IS IN SIGHT. HE UNDERSTANDS THE LOGIC OF APCH CTL TO TAKE THE TFC TO VICTOR 408 WHERE THE MOUNTAINS ARE TO GET AROUND THE NEW YORK TFC AREA. BUT; HE FEELS APCH SHOULD NOT CLR AIRLINERS FOR THE VISUAL UNTIL BEYOND THE RIDGE LINES AS MATTER OF PROC.