Narrative:

Air carrier X was being vectored for visual approach to runway 23. I was working ar/west radar position and was responsible for calling the sequence. I had given a sequence earlier to ar/east to run his (practice low approach) small aircraft Y and I would follow him. I determined that due to my traffic volume and how far out I would have to take air carrier X to follow an small transport doing about 90- 100 KTS that I would run air carrier X first to runway 23. Air carrier X was about 4-5 nnw of cak on downwind at the time I told ar/east to break out his small aircraft Y in sufficient time to affect this change. Ar/east came back and told me local controller was providing and would break out small aircraft Y as necessary. Small aircraft Y was on 7 mi final. I cleared air carrier X for visual approach to runway 23. WX was VFR. I assumed that local control was providing visual separation between the aircraft (he was talking to small aircraft Y or he would have broken him out as I instructed). Air carrier X was then changed to local controller frequency. Air carrier X on his base leg to final lost separation with small aircraft Y on final and local controller says he couldn't see small aircraft Y visually. Ar/east and/or local control should have broken small aircraft Y out when I instructed and no system error would have occurred. Local controller should not have taken on the responsibility of 'providing' visual separation if he could not see the aircraft involved. Supplemental information from acn 196795. Air carrier X approached cak arsa from the southeast. Cak was split (east/west) operation. Small aircraft Y was working the east controller on ILS runway 23 approach. For practice approach. Runway 19 was closed for some construction activity. WX was about 3000 ft overcast visibility 7 but due to poor contrast with clouds this was a difficult day to see aircraft. From the tower I could not see most arrs until they were 2 or 3 mi from the airport. The west controller was fairly busy and air carrier X would have been last of about 4 or 5 aircraft on the approach. The west controller decided instead to try and put air carrier X on a short approach for a visual approach in front of small aircraft Y on the ILS. Air carrier X never turned base and was headed straight at small aircraft Y (opposite direction traffic). The east controller had coordinated a 190 degree heading for small aircraft Y for missed approach instructions. I turned small aircraft Y to the 190 degree heading when I lost 3 mi but the speed difference of the 2 aircraft was too great and the targets merged with air carrier X mode C indicating 3000 ft and small aircraft X mode C 3100 ft. This incident was created by several factors. Traffic saturation, caused by 1 runway operation, too many practice approach aircraft mixed with itinerants. Aircraft speed, air carrier X was at least 260 KTS ground speed. At this speed he washed through a wide turn and had difficulty losing altitude. Speed difference, air carrier X was 2 1/2 to 3 times the speed of small aircraft Y. Supplemental information from acn 196137. Controller east was issued approach sequence by controller west as #1 small aircraft Y cleared for ILS runway 23 approach and switched to tower on a 7 mi final. Controller west advised he would beat small aircraft Y with air carrier X 5 northwest of cak and later said break out small aircraft Y. Controller east advised controller in tower of situation and issued a missed approach if deemed necessary. Controller west failed to switch air carrier X to local controller. Local controller failed to see if air carrier X was on his frequency and reacted too late turning small aircraft Y out on a missed approach. Controller west never should have changed arrival sequence. Additionally west controller was providing visual separation according to local directives and if he could not comply he should have advised controllers east and west.

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Original NASA ASRS Text

Title: ACR X HAD NMAC LTSS SEPARATION FROM SMA Y. SYS ERROR.

Narrative: ACR X WAS BEING VECTORED FOR VISUAL APCH TO RWY 23. I WAS WORKING AR/W RADAR POS AND WAS RESPONSIBLE FOR CALLING THE SEQUENCE. I HAD GIVEN A SEQUENCE EARLIER TO AR/E TO RUN HIS (PRACTICE LOW APCH) SMA Y AND I WOULD FOLLOW HIM. I DETERMINED THAT DUE TO MY TFC VOLUME AND HOW FAR OUT I WOULD HAVE TO TAKE ACR X TO FOLLOW AN SMT DOING ABOUT 90- 100 KTS THAT I WOULD RUN ACR X FIRST TO RWY 23. ACR X WAS ABOUT 4-5 NNW OF CAK ON DOWNWIND AT THE TIME I TOLD AR/E TO Break OUT HIS SMA Y IN SUFFICIENT TIME TO AFFECT THIS CHANGE. AR/E CAME BACK AND TOLD ME LCL CTLR WAS PROVIDING AND WOULD BREAK OUT SMA Y AS NECESSARY. SMA Y WAS ON 7 MI FINAL. I CLRED ACR X FOR VISUAL APCH TO RWY 23. WX WAS VFR. I ASSUMED THAT LCL CTL WAS PROVIDING VISUAL SEPARATION BTWN THE ACFT (HE WAS TALKING TO SMA Y OR HE WOULD HAVE BROKEN HIM OUT AS I INSTRUCTED). ACR X WAS THEN CHANGED TO LCL CTLR FREQ. ACR X ON HIS BASE LEG TO FINAL LOST SEPARATION WITH SMA Y ON FINAL AND LCL CTLR SAYS HE COULDN'T SEE SMA Y VISUALLY. AR/E AND/OR LCL CTL SHOULD HAVE BROKEN SMA Y OUT WHEN I INSTRUCTED AND NO SYS ERROR WOULD HAVE OCCURRED. LCL CTLR SHOULD NOT HAVE TAKEN ON THE RESPONSIBILITY OF 'PROVIDING' VISUAL SEPARATION IF HE COULD NOT SEE THE ACFT INVOLVED. SUPPLEMENTAL INFO FROM ACN 196795. ACR X APCHED CAK ARSA FROM THE SE. CAK WAS SPLIT (E/W) OP. SMA Y WAS WORKING THE E CTLR ON ILS RWY 23 APCH. FOR PRACTICE APCH. RWY 19 WAS CLOSED FOR SOME CONSTRUCTION ACTIVITY. WX WAS ABOUT 3000 FT OVCST VISIBILITY 7 BUT DUE TO POOR CONTRAST WITH CLOUDS THIS WAS A DIFFICULT DAY TO SEE ACFT. FROM THE TWR I COULD NOT SEE MOST ARRS UNTIL THEY WERE 2 OR 3 MI FROM THE ARPT. THE W CTLR WAS FAIRLY BUSY AND ACR X WOULD HAVE BEEN LAST OF ABOUT 4 OR 5 ACFT ON THE APCH. THE W CTLR DECIDED INSTEAD TO TRY AND PUT ACR X ON A SHORT APCH FOR A VISUAL APCH IN FRONT OF SMA Y ON THE ILS. ACR X NEVER TURNED BASE AND WAS HEADED STRAIGHT AT SMA Y (OPPOSITE DIRECTION TFC). THE E CTLR HAD COORDINATED A 190 DEG HDG FOR SMA Y FOR MISSED APCH INSTRUCTIONS. I TURNED SMA Y TO THE 190 DEG HDG WHEN I LOST 3 MI BUT THE SPD DIFFERENCE OF THE 2 ACFT WAS TOO GREAT AND THE TARGETS MERGED WITH ACR X MODE C INDICATING 3000 FT AND SMA X MODE C 3100 FT. THIS INCIDENT WAS CREATED BY SEVERAL FACTORS. TFC SATURATION, CAUSED BY 1 RWY OP, TOO MANY PRACTICE APCH ACFT MIXED WITH ITINERANTS. ACFT SPD, ACR X WAS AT LEAST 260 KTS GND SPD. AT THIS SPD HE WASHED THROUGH A WIDE TURN AND HAD DIFFICULTY LOSING ALT. SPD DIFFERENCE, ACR X WAS 2 1/2 TO 3 TIMES THE SPD OF SMA Y. SUPPLEMENTAL INFO FROM ACN 196137. CTLR E WAS ISSUED APCH SEQUENCE BY CTLR W AS #1 SMA Y CLRED FOR ILS RWY 23 APCH AND SWITCHED TO TWR ON A 7 MI FINAL. CTLR W ADVISED HE WOULD BEAT SMA Y WITH ACR X 5 NW OF CAK AND LATER SAID BREAK OUT SMA Y. CTLR E ADVISED CTLR IN TWR OF SITUATION AND ISSUED A MISSED APCH IF DEEMED NECESSARY. CTLR W FAILED TO SWITCH ACR X TO LCL CTLR. LCL CTLR FAILED TO SEE IF ACR X WAS ON HIS FREQ AND REACTED TOO LATE TURNING SMA Y OUT ON A MISSED APCH. CTLR W NEVER SHOULD HAVE CHANGED ARR SEQUENCE. ADDITIONALLY W CTLR WAS PROVIDING VISUAL SEPARATION ACCORDING TO LCL DIRECTIVES AND IF HE COULD NOT COMPLY HE SHOULD HAVE ADVISED CTLRS E AND W.

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.