Narrative:

We were being vectored for visual to 17L at dfw, following company traffic ahead. Regional approach called traffic at our 1-2 O'clock, 4 mi, altitude unknown. Traffic was spotted immediately and appeared to be going to 17L. The first officer was flying and did not see traffic right away. I watched traffic, finally realizing he was coming directly at us. We had been cleared from 5000 ft to 3000 ft. We were passing through 3500 when I saw he was coming at us. The first officer asked what to do and I told him to descend immediately. He passed overhead what appeared to be 500-800 ft. He was at 3500 ft as we descended to 3000 ft. The darkness affected our vision which made it hard initially to tell his direction and altitude. He appeared to be the size of an small transport twin. He never saw us or took any evasive action. We did not have TCASII on board which would have given us an early indication of his direction and altitude. I was worried that he was descending into love field behind us, but I finally decided he was level at 3500 ft. I believe he must have been in the TCA without permission because he was not talking to approach. He also flew right across the final approach for 17L and 18R at dfw without permission. No passenger were injured in our abrupt nose over maneuver. I don't believe approach ever gave us the aircraft's direction of flight which would have helped.

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Original NASA ASRS Text

Title: POTENTIAL CONFLICT AS NMAC AVOIDED IN ACR FLC RESPONSE TO TA GIVEN WAS TO PERFORM AN EVASIVE ACTION DIVE.

Narrative: WE WERE BEING VECTORED FOR VISUAL TO 17L AT DFW, FOLLOWING COMPANY TFC AHEAD. REGIONAL APCH CALLED TFC AT OUR 1-2 O'CLOCK, 4 MI, ALT UNKNOWN. TFC WAS SPOTTED IMMEDIATELY AND APPEARED TO BE GOING TO 17L. THE FO WAS FLYING AND DID NOT SEE TFC RIGHT AWAY. I WATCHED TFC, FINALLY REALIZING HE WAS COMING DIRECTLY AT US. WE HAD BEEN CLRED FROM 5000 FT TO 3000 FT. WE WERE PASSING THROUGH 3500 WHEN I SAW HE WAS COMING AT US. THE FO ASKED WHAT TO DO AND I TOLD HIM TO DSND IMMEDIATELY. HE PASSED OVERHEAD WHAT APPEARED TO BE 500-800 FT. HE WAS AT 3500 FT AS WE DSNDED TO 3000 FT. THE DARKNESS AFFECTED OUR VISION WHICH MADE IT HARD INITIALLY TO TELL HIS DIRECTION AND ALT. HE APPEARED TO BE THE SIZE OF AN SMT TWIN. HE NEVER SAW US OR TOOK ANY EVASIVE ACTION. WE DID NOT HAVE TCASII ON BOARD WHICH WOULD HAVE GIVEN US AN EARLY INDICATION OF HIS DIRECTION AND ALT. I WAS WORRIED THAT HE WAS DSNDING INTO LOVE FIELD BEHIND US, BUT I FINALLY DECIDED HE WAS LEVEL AT 3500 FT. I BELIEVE HE MUST HAVE BEEN IN THE TCA WITHOUT PERMISSION BECAUSE HE WAS NOT TALKING TO APCH. HE ALSO FLEW RIGHT ACROSS THE FINAL APCH FOR 17L AND 18R AT DFW WITHOUT PERMISSION. NO PAX WERE INJURED IN OUR ABRUPT NOSE OVER MANEUVER. I DON'T BELIEVE APCH EVER GAVE US THE ACFT'S DIRECTION OF FLT WHICH WOULD HAVE HELPED.

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.