Narrative:

While we were level at 10000 MSL, ATC advised of an small aircraft, 12 O'clock, opposite direction at either 8800 MSL or 9800 MSL (not sure). The small aircraft had reported us in sight. TCASII gave us an RA calling for a min of a 2000 FPM climb which we did to 11000 MSL. It showed the small aircraft at 9800 MSL, 12 O'clock, 2 mi. When we reached 11000 MSL, a few seconds later, we saw the small aircraft at 3 O'clock about 1200 ft lower as the TCASII displayed. Had we stayed at 10000 we believe separation would have been 200 ft vertically and about 3/4 mi horizontally. We then descended to 8000 (new clearance) and no other action was taken.

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Original NASA ASRS Text

Title: ACR MLG ALTDEV EXCURSION FROM CLRNC ALT IN RESPONSE TO TCASII RA.

Narrative: WHILE WE WERE LEVEL AT 10000 MSL, ATC ADVISED OF AN SMA, 12 O'CLOCK, OPPOSITE DIRECTION AT EITHER 8800 MSL OR 9800 MSL (NOT SURE). THE SMA HAD RPTED US IN SIGHT. TCASII GAVE US AN RA CALLING FOR A MIN OF A 2000 FPM CLB WHICH WE DID TO 11000 MSL. IT SHOWED THE SMA AT 9800 MSL, 12 O'CLOCK, 2 MI. WHEN WE REACHED 11000 MSL, A FEW SECONDS LATER, WE SAW THE SMA AT 3 O'CLOCK ABOUT 1200 FT LOWER AS THE TCASII DISPLAYED. HAD WE STAYED AT 10000 WE BELIEVE SEPARATION WOULD HAVE BEEN 200 FT VERTICALLY AND ABOUT 3/4 MI HORIZLY. WE THEN DSNDED TO 8000 (NEW CLRNC) AND NO OTHER ACTION WAS TAKEN.

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.