BTV CTLR EXPERIENCED LOSS OF SEPARATION BTWN ARR AND DEP TFC.

Narrative

I WAS ASSIGNED THE E ARR RADAR POS; WHICH ROUTINELY OPERATES WITH 2 RADAR SECTORS COMBINED. THIS WAS THE CONFIGN AT THE TIME OF THE INCIDENT. I HAD BEEN ON THE POS FOR 11 MINS WHEN THE INCIDENT OCCURRED. I WAS WORKING 8 ACFT; WHICH WERE SCATTERED THROUGHOUT THE APCH CTL AIRSPACE. ACFT #1 WAS AN IFR RWY 1 DEP FROM BURLINGTON ARPT (BTV); INITIALLY ASSIGNED RWY HEADING BY THE TWR. THE CTLR PRIOR TO MYSELF ISSUED A 100 DEG HDG; FOLLOWED SHORTLY BY A 120 DEG HDG FOR TFC INBOUND TO THE ARPT FROM THE S. THE ACFT WAS ASSIGNED 7000 FT. WHEN THE TFC WAS NO FACTOR; I ISSUED A 160 DEG HDG WITH INSTRUCTION TO PROCEED DIRECT TO THE LEBANON (LEB) VORTAC WHEN ABLE. THIS ACFT WAS GPS-EQUIPPED; SO THE TIME FRAME FOR THE ACFT TO HAVE BEEN FLYING THE 160 DEG HDG SHOULD HAVE BEEN MINIMAL. ACFT #2 WAS AN IFR ARR TO BTV FROM THE S (NOT THE ORIGINAL TFC FOR ACFT #1). ACFT #2 WAS LEVEL AT 7000 FT. ACFT #2 CAME ON FREQ WITH A VERY WEAK RADIO; OF WHICH I ADVISED THE PLT. I ALSO ADVISED ACFT #2 TO EXPECT A VISUAL APCH TO RWY 33. SEVERAL MINS AFTER INITIAL CONTACT; ACFT #2 REQUESTED AN ILS/DME APCH TO RWY 33. I ISSUED A 070 DEG HDG TO THE RWY 33 LOC. I THEN TENDED TO OTHER HIGHER PRIORITY DUTIES; INCLUDING THE ISSUANCE OF MANDATORY TA'S TO VFR ACFT LOCATED WITHIN THE BTV CLASS C AIRSPACE AND ASSOCIATED OUTER AREA. AT THIS TIME; I DID NOT BELIEVE THAT ACFT #1 AND ACFT #2 WOULD BECOME FACTORS FOR EACH OTHER. WHEN I RETURNED MY ATTN TO ACFT #2 FOR THE TURN TO FINAL; I FIRST NOTICED THE ACFT WAS A BIT TOO CLOSE TO THE FIX FROM WHERE THE APCH COMMENCED AND WAS ABOUT TO ISSUE A VECTOR TO WIDEN THE ACFT PATH. I NOTICED THE PROX OF ACFT #1 AND IMMEDIATELY ISSUED A DSCNT INSTRUCTION TO ACFT #2. AT THIS TIME; THERE WAS NOTHING THAT COULD BE DONE TO PREVENT THE LOSS OF SEPARATION BTWN THE ACFT; SO THE ACTION TAKEN WAS TO MITIGATE THE SEPARATION LOSS. I WAS FRANKLY SURPRISED BY THE PROX OF THE 2 ACFT. THE REPLAY OF THE RADAR DATA INDICATED THE ACFT WAS TRACKING NEARLY DUE S FOR SEVERAL MI; COMING MUCH CLOSER TO THE RWY 33 LOC THAN I WOULD HAVE EXPECTED. IN RETROSPECT; ISSUING A DSCNT TO ACFT #2 AT THE SAME TIME AS THE INITIAL VECTOR TO THE LOC WOULD HAVE BEEN A PRUDENT MOVE AND WOULD ALMOST CERTAINLY HAVE PREVENTED THE LOSS OF SEPARATION. I HAVE BEEN FACED WITH SIMILAR SITS AND IN MOST CASES; WOULD HAVE GIVEN BOTH CTL INSTRUCTIONS SIMULTANEOUSLY. I AM UNABLE TO PINPOINT WHY I DID NOT DO THAT IN THIS INSTANCE; BUT IT IS POSSIBLE IT HAD SOMETHING TO DO WITH THE WEAK RADIO OR A HIGHER PRIORITY DUTY. OTHER POINTS: 1) THERE WERE AT LEAST 4 OTHER CTLR PERSONNEL IN THE TRACON AT THE TIME OF THE INCIDENT; INCLUDING ONE OPS SUPVR. MOST OF THESE PERSONNEL WERE ENGAGED IN CONVERSATION AT THE SUPVR'S DESK. THE ARR DATA CTLR; WHO ORDINARILY WOULD BE SEATED ADJACENT TO THE ARR RADAR POS; WAS NOT THERE BUT WAS NEAR THE SUPVR'S DESK. IF AT LEAST ONE OF THOSE INDIVIDUALS HAD BEEN WATCHING A RADAR SCOPE; THEN; MORE THAN LIKELY; THE INCIDENT COULD HAVE BEEN PREVENTED. 2) THE BUILT-IN CONFLICT ALERT (CA) PROBE OF THE ARTS IIE EQUIP; WHILE PROBABLY FUNCTIONING AS DESIGNED; WAS TOTALLY USELESS IN THIS INSTANCE TO PREVENT A LOSS OF SEPARATION. THE CA DIDN'T SOUND UNTIL WELL AFTER I REALIZED THE LOSS OF SEPARATION WAS OCCURRING. WHEN THE CA SOUNDED; THE ACFT TARGETS WERE NEARLY ON TOP OF EACH OTHER WITH ALREADY INCREASING SEPARATION. INDEED; THE CTLR'S DEFINITION FOR 'CA' IS 'COMING APART.' A MORE USEFUL TOOL WOULD BE A WARNING WELL PRIOR TO THE LOSS OF SEPARATION OCCURRING. THAT IS; A PROBE THAT EXTENDS 5-10 MI AHEAD OF THE ACFT. WHILE I CAN BLAME NO ONE BUT MYSELF FOR THIS OCCURRENCE; I CAN'T HELP BUT BELIEVE THAT WITH JUST 1 OR 2 FACTORS SLIGHTLY DIFFERENT; THE INCIDENT WOULD NEVER HAVE OCCURRED.