Narrative:

This event occurred on txk-lo at ZFW. I was providing OJT to another cpc (training not a factor). We were working aircraft Y (B1900) dfw..eld at 10000 ft. The flight was eastbound. We observed a fast moving VFR intruder target indicating 10000 ft; at 10 O'clock position to the aircraft Y. We called the traffic; which passed about 1 - 1 1/2 mi left to right slightly converging in front of the aircraft Y. The pilot of aircraft Y reported the traffic in sight. When the VFR was about 5 O'clock position; 6 mi behind aircraft Y; it began a wide left turn -- altitude still indicating 10000 ft (or within a few hundred ft). After the turn; we again issued traffic to the aircraft Y. 'Looking' was the reply. The VFR continued nebound on a converging course with aircraft Y. The cpc-it again called traffic and issued a descent to aircraft Y. The pilot reported that traffic in sight. I asked what type aircraft the other traffic was; and the pilot of aircraft Y reported it to be a lance 4. Then; the VFR traffic moved so close to the aircraft Y -- vertical and horizontal -- that we actually lost radar returns on both aircraft. The pilot's voice was shaky; so I overrode the cpc-it and authority/authorized the aircraft Y to maneuver left or right and authority/authorized a descent to 2000 ft. The VFR traffic then moved away nebound from aircraft Y. I recalled working an aircraft X into txk earlier in the shift; so I called the txk ATCT and asked if they might be working a VFR aircraft X to the south of the field. They replied yes; and the aircraft idented as requested. I asked the tower if that was the same aircraft from earlier; and he replied yes. In reference to that incident; I worked a traffic pattern into txk runway 22; where the sequence was #1/IFR air carrier aircraft Z (left traffic); #2 VFR aircraft X (right traffic); and #3 IFR GA (right traffic). The aircraft X reported the airport in sight; I advised him he was #2 to follow an aircraft Z left traffic; and switched him to tower. I later observed the VFR target and the aircraft Z target merge on 4 mi final. I then observed a beacon only target execute a left 360 degree turn. Later still; I asked the tower controller if he had put the aircraft X in front of the aircraft Z; and he replied 'no; the aircraft X cut him off and had to go around.'

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Original NASA ASRS Text

Title: ZFW CTLR DESCRIBED CONFLICT BETWEEN IFR AND UNKNOWN VFR TFC; CITING A NUMBER OF POTENTIAL CONFLICTIONS; ENDING WITH A TFC PATTERN EVENT.

Narrative: THIS EVENT OCCURRED ON TXK-LO AT ZFW. I WAS PROVIDING OJT TO ANOTHER CPC (TRAINING NOT A FACTOR). WE WERE WORKING ACFT Y (B1900) DFW..ELD AT 10000 FT. THE FLT WAS EBOUND. WE OBSERVED A FAST MOVING VFR INTRUDER TARGET INDICATING 10000 FT; AT 10 O'CLOCK POS TO THE ACFT Y. WE CALLED THE TFC; WHICH PASSED ABOUT 1 - 1 1/2 MI L TO R SLIGHTLY CONVERGING IN FRONT OF THE ACFT Y. THE PLT OF ACFT Y RPTED THE TFC IN SIGHT. WHEN THE VFR WAS ABOUT 5 O'CLOCK POS; 6 MI BEHIND ACFT Y; IT BEGAN A WIDE L TURN -- ALT STILL INDICATING 10000 FT (OR WITHIN A FEW HUNDRED FT). AFTER THE TURN; WE AGAIN ISSUED TFC TO THE ACFT Y. 'LOOKING' WAS THE REPLY. THE VFR CONTINUED NEBOUND ON A CONVERGING COURSE WITH ACFT Y. THE CPC-IT AGAIN CALLED TFC AND ISSUED A DSCNT TO ACFT Y. THE PLT RPTED THAT TFC IN SIGHT. I ASKED WHAT TYPE ACFT THE OTHER TFC WAS; AND THE PLT OF ACFT Y RPTED IT TO BE A LANCE 4. THEN; THE VFR TFC MOVED SO CLOSE TO THE ACFT Y -- VERT AND HORIZ -- THAT WE ACTUALLY LOST RADAR RETURNS ON BOTH ACFT. THE PLT'S VOICE WAS SHAKY; SO I OVERRODE THE CPC-IT AND AUTH THE ACFT Y TO MANEUVER L OR R AND AUTH A DSCNT TO 2000 FT. THE VFR TFC THEN MOVED AWAY NEBOUND FROM ACFT Y. I RECALLED WORKING AN ACFT X INTO TXK EARLIER IN THE SHIFT; SO I CALLED THE TXK ATCT AND ASKED IF THEY MIGHT BE WORKING A VFR ACFT X TO THE S OF THE FIELD. THEY REPLIED YES; AND THE ACFT IDENTED AS REQUESTED. I ASKED THE TWR IF THAT WAS THE SAME ACFT FROM EARLIER; AND HE REPLIED YES. IN REF TO THAT INCIDENT; I WORKED A TFC PATTERN INTO TXK RWY 22; WHERE THE SEQUENCE WAS #1/IFR ACR ACFT Z (L TFC); #2 VFR ACFT X (R TFC); AND #3 IFR GA (R TFC). THE ACFT X RPTED THE ARPT IN SIGHT; I ADVISED HIM HE WAS #2 TO FOLLOW AN ACFT Z L TFC; AND SWITCHED HIM TO TWR. I LATER OBSERVED THE VFR TARGET AND THE ACFT Z TARGET MERGE ON 4 MI FINAL. I THEN OBSERVED A BEACON ONLY TARGET EXECUTE A L 360 DEG TURN. LATER STILL; I ASKED THE TWR CTLR IF HE HAD PUT THE ACFT X IN FRONT OF THE ACFT Z; AND HE REPLIED 'NO; THE ACFT X CUT HIM OFF AND HAD TO GO AROUND.'

Data retrieved from NASA's ASRS site as of May 2009 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.