Narrative:

Air carrier X was being radar vectored from scurry to dfw airport for a landing to the south runways (17 or 18). Upon turning to a 350 degree heading parallel to runway 17L and approximately 6 mi east of dfw, we were given step down dscnts from 11000 ft to 6000 ft MSL. Abeam the approach end of runway 17L we were in a descent passing approximately 8000 ft and told there was a 'heavy md-11' ahead that we would be following to the runway. We had him in sight and on TCASII at approximately 6 mi. At no time were we told to expect a visual to runway 18. If we were told, we never heard it nor did we acknowledge the call (radios were very busy with arrival traffic to dfw). Approximately 10 mi northeast of dfw on a 270 degree heading we were 'cleared the visual behind the heavy.' no runway was given so we assumed the controller meant to runway 17. Shortly thereafter, we were told to contact tower on the frequency for the west runway complex (runway 18). This puzzled us but radios were very busy, so we switched to the tower frequency for the east runways--assuming the controller must have been mistaken. Shortly thereafter (8 mi final), we received a TCASII warning (TA) for traffic that was 1000 ft below. We were on a descent for the runway at approximately 3800 ft MSL. The aircraft below was apparently on a similar course because as we continued our descent, the altitude separation was quickly diminishing--yet he was still directly below us. When we leveled off, there was 300 ft of separation and TCASII was giving the RA to climb. At that moment, tower told us to 'turn right' and cleared the visual to runway 18R. Air carrier Y that was below us causing the TCASII warning apparently had us in sight, but we could not see him, and in the seconds that all this was happening, he was also querying the tower about where we were going.

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Original NASA ASRS Text

Title: ACR X APCH TO WRONG RWY HAD NMAC WITH ACR Y. ACR X TCASII TA RA EVASIVE ACTION TAKEN.

Narrative: ACR X WAS BEING RADAR VECTORED FROM SCURRY TO DFW ARPT FOR A LNDG TO THE S RWYS (17 OR 18). UPON TURNING TO A 350 DEG HDG PARALLEL TO RWY 17L AND APPROX 6 MI E OF DFW, WE WERE GIVEN STEP DOWN DSCNTS FROM 11000 FT TO 6000 FT MSL. ABEAM THE APCH END OF RWY 17L WE WERE IN A DSCNT PASSING APPROX 8000 FT AND TOLD THERE WAS A 'HEAVY MD-11' AHEAD THAT WE WOULD BE FOLLOWING TO THE RWY. WE HAD HIM IN SIGHT AND ON TCASII AT APPROX 6 MI. AT NO TIME WERE WE TOLD TO EXPECT A VISUAL TO RWY 18. IF WE WERE TOLD, WE NEVER HEARD IT NOR DID WE ACKNOWLEDGE THE CALL (RADIOS WERE VERY BUSY WITH ARR TFC TO DFW). APPROX 10 MI NE OF DFW ON A 270 DEG HDG WE WERE 'CLRED THE VISUAL BEHIND THE HVY.' NO RWY WAS GIVEN SO WE ASSUMED THE CTLR MEANT TO RWY 17. SHORTLY THEREAFTER, WE WERE TOLD TO CONTACT TWR ON THE FREQ FOR THE W RWY COMPLEX (RWY 18). THIS PUZZLED US BUT RADIOS WERE VERY BUSY, SO WE SWITCHED TO THE TWR FREQ FOR THE E RWYS--ASSUMING THE CTLR MUST HAVE BEEN MISTAKEN. SHORTLY THEREAFTER (8 MI FINAL), WE RECEIVED A TCASII WARNING (TA) FOR TFC THAT WAS 1000 FT BELOW. WE WERE ON A DSCNT FOR THE RWY AT APPROX 3800 FT MSL. THE ACFT BELOW WAS APPARENTLY ON A SIMILAR COURSE BECAUSE AS WE CONTINUED OUR DSCNT, THE ALT SEPARATION WAS QUICKLY DIMINISHING--YET HE WAS STILL DIRECTLY BELOW US. WHEN WE LEVELED OFF, THERE WAS 300 FT OF SEPARATION AND TCASII WAS GIVING THE RA TO CLB. AT THAT MOMENT, TWR TOLD US TO 'TURN R' AND CLRED THE VISUAL TO RWY 18R. ACR Y THAT WAS BELOW US CAUSING THE TCASII WARNING APPARENTLY HAD US IN SIGHT, BUT WE COULD NOT SEE HIM, AND IN THE SECONDS THAT ALL THIS WAS HAPPENING, HE WAS ALSO QUERYING THE TWR ABOUT WHERE WE WERE GOING.

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.