Narrative:

Being vectored on a left base to runway 1R, crew noticed another aircraft at the same altitude (5000 ft) on TCASII, which appeared to be on a right base for the same ILS to runway 1R. Both crew members verbalized, 'this could be a potential conflict.' moments later we received a traffic alert. Other incident aircraft questioned controller about us and was told, 'other aircraft no factor.' first officer was also trying to query the controller, but was unable due to other xmissions. While being vectored across final and given a left turn back to intercept ILS runway 1R, an RA occurred (monitor vertical speed). Crew followed RA guidance while complying with ATC clearance and a climb resulted to 5280 ft. Vertical speed was used to descend back to 5000 ft. We were then revectored for another ILS to runway 1R for an uneventful landing.

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Original NASA ASRS Text

Title: B737-300 FLC RESPOND TO TCASII RA DUE TO OPPOSITE DIRECTION, SAME ALT ACR, BOTH ON VECTOR TO IAD RWY 1R.

Narrative: BEING VECTORED ON A L BASE TO RWY 1R, CREW NOTICED ANOTHER ACFT AT THE SAME ALT (5000 FT) ON TCASII, WHICH APPEARED TO BE ON A R BASE FOR THE SAME ILS TO RWY 1R. BOTH CREW MEMBERS VERBALIZED, 'THIS COULD BE A POTENTIAL CONFLICT.' MOMENTS LATER WE RECEIVED A TFC ALERT. OTHER INCIDENT ACFT QUESTIONED CTLR ABOUT US AND WAS TOLD, 'OTHER ACFT NO FACTOR.' FO WAS ALSO TRYING TO QUERY THE CTLR, BUT WAS UNABLE DUE TO OTHER XMISSIONS. WHILE BEING VECTORED ACROSS FINAL AND GIVEN A L TURN BACK TO INTERCEPT ILS RWY 1R, AN RA OCCURRED (MONITOR VERT SPD). CREW FOLLOWED RA GUIDANCE WHILE COMPLYING WITH ATC CLRNC AND A CLB RESULTED TO 5280 FT. VERT SPD WAS USED TO DSND BACK TO 5000 FT. WE WERE THEN REVECTORED FOR ANOTHER ILS TO RWY 1R FOR AN UNEVENTFUL LNDG.

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.