Narrative:

Small transport Y had been cleared to land runway 18L. Small aircraft X was cleared for takeoff runway 18R with a left turn heading 090. Small aircraft X turned in front of the landing small transport Y. Y's pilot asked if I saw the small aircraft, and I said affirmative. However, I did not see small aircraft X start the left turn due to other traffic on the final. I had diverted my attention after issuing X's takeoff clearance to large transport Z following small transport Y to runway 18L. Large transport Z was gaining on small transport Y, and I had to change his runway to 18R. This diverted my attention away from small aircraft X. I did not see X start his turn; only after X was in front and above the landing Y. I feel small aircraft X made an early turn, and this was the cause of the incident. I suggest pilots be required to request early turnouts to prevent this from happening again.

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Original NASA ASRS Text

Title: NMAC BETWEEN SMA AND ATX.

Narrative: SMT Y HAD BEEN CLRED TO LAND RWY 18L. SMA X WAS CLRED FOR TKOF RWY 18R WITH A LEFT TURN HDG 090. SMA X TURNED IN FRONT OF THE LNDG SMT Y. Y'S PLT ASKED IF I SAW THE SMA, AND I SAID AFFIRMATIVE. HOWEVER, I DID NOT SEE SMA X START THE LEFT TURN DUE TO OTHER TFC ON THE FINAL. I HAD DIVERTED MY ATTN AFTER ISSUING X'S TKOF CLRNC TO LGT Z FOLLOWING SMT Y TO RWY 18L. LGT Z WAS GAINING ON SMT Y, AND I HAD TO CHANGE HIS RWY TO 18R. THIS DIVERTED MY ATTN AWAY FROM SMA X. I DID NOT SEE X START HIS TURN; ONLY AFTER X WAS IN FRONT AND ABOVE THE LNDG Y. I FEEL SMA X MADE AN EARLY TURN, AND THIS WAS THE CAUSE OF THE INCIDENT. I SUGGEST PLTS BE REQUIRED TO REQUEST EARLY TURNOUTS TO PREVENT THIS FROM HAPPENING AGAIN.

Data retrieved from NASA's ASRS site as of August 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.