Narrative:

We were en route in LNAV at FL310, 30 mi north of atl. As center was giving us a frequency change, we got a TA on the TCASII. Both my first officer and I had to turn our map range down to 10 mi because the TA target was so close. I told ZTL to 'stand by, we have a TA on the TCASII.' the target was at 12 O'clock position and 5 mi. Approximately 1 second later, the target was at 12:30 O'clock position and 4 mi. The target passed less than 2 mi off our right at our altitude. Our heading was 210 degrees, the target heading was approximately 340 degrees. I reported to center that the traffic passed less than 2 mi off our right and the other aircraft agreed, less than 2 mi. I then asked center what that was all about, and they said that they were taking care of it. We then received a frequency change. We did not ever get an RA, and we never changed course or altitude. The traffic went by so fast (approximately 900 KTS closure rate) that we didn't have time to make out the aircraft type.

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Original NASA ASRS Text

Title: A B737 FLT CREW RECEIVE A TCASII TA WHILE CRUISING AT FL310 UNDER ZTL CTL.

Narrative: WE WERE ENRTE IN LNAV AT FL310, 30 MI N OF ATL. AS CTR WAS GIVING US A FREQ CHANGE, WE GOT A TA ON THE TCASII. BOTH MY FO AND I HAD TO TURN OUR MAP RANGE DOWN TO 10 MI BECAUSE THE TA TARGET WAS SO CLOSE. I TOLD ZTL TO 'STAND BY, WE HAVE A TA ON THE TCASII.' THE TARGET WAS AT 12 O'CLOCK POS AND 5 MI. APPROX 1 SECOND LATER, THE TARGET WAS AT 12:30 O'CLOCK POS AND 4 MI. THE TARGET PASSED LESS THAN 2 MI OFF OUR R AT OUR ALT. OUR HDG WAS 210 DEGS, THE TARGET HDG WAS APPROX 340 DEGS. I RPTED TO CTR THAT THE TFC PASSED LESS THAN 2 MI OFF OUR R AND THE OTHER ACFT AGREED, LESS THAN 2 MI. I THEN ASKED CTR WHAT THAT WAS ALL ABOUT, AND THEY SAID THAT THEY WERE TAKING CARE OF IT. WE THEN RECEIVED A FREQ CHANGE. WE DID NOT EVER GET AN RA, AND WE NEVER CHANGED COURSE OR ALT. THE TFC WENT BY SO FAST (APPROX 900 KTS CLOSURE RATE) THAT WE DIDN'T HAVE TIME TO MAKE OUT THE ACFT TYPE.

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.