Narrative:

I was assigned the east arrival radar position, which routinely operates with 2 radar sectors combined. This was the confign at the time of the incident. I had been on the position for 11 mins when the incident occurred. I was working 8 aircraft, which were scattered throughout the approach control airspace. Aircraft #1 was an IFR runway 1 departure from burlington airport (btv), initially assigned runway heading by the tower. The controller prior to myself issued a 100 degree heading, followed shortly by a 120 degree heading for traffic inbound to the airport from the south. The aircraft was assigned 7000 ft. When the traffic was no factor, I issued a 160 degree heading with instruction to proceed direct to the lebanon (leb) VORTAC when able. This aircraft was GPS-equipped, so the time frame for the aircraft to have been flying the 160 degree heading should have been minimal. Aircraft #2 was an IFR arrival to btv from the south (not the original traffic for aircraft #1). Aircraft #2 was level at 7000 ft. Aircraft #2 came on frequency with a very weak radio, of which I advised the pilot. I also advised aircraft #2 to expect a visual approach to runway 33. Several mins after initial contact, aircraft #2 requested an ILS/DME approach to runway 33. I issued a 070 degree heading to the runway 33 localizer. I then tended to other higher priority duties, including the issuance of mandatory TA's to VFR aircraft located within the btv class C airspace and associated outer area. At this time, I did not believe that aircraft #1 and aircraft #2 would become factors for each other. When I returned my attention to aircraft #2 for the turn to final, I first noticed the aircraft was a bit too close to the fix from where the approach commenced and was about to issue a vector to widen the aircraft path. I noticed the proximity of aircraft #1 and immediately issued a descent instruction to aircraft #2. At this time, there was nothing that could be done to prevent the loss of separation between the aircraft, so the action taken was to mitigate the separation loss. I was frankly surprised by the proximity of the 2 aircraft. The replay of the radar data indicated the aircraft was tracking nearly due south for several mi, coming much closer to the runway 33 localizer than I would have expected. In retrospect, issuing a descent to aircraft #2 at the same time as the initial vector to the localizer 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 control 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 controller personnel in the TRACON at the time of the incident, including one operations supervisor. Most of these personnel were engaged in conversation at the supervisor's desk. The arrival data controller, who ordinarily would be seated adjacent to the arrival radar position, was not there but was near the supervisor'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 equipment, 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 aircraft targets were nearly on top of each other with already increasing separation. Indeed, the controller'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 aircraft. 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.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.