Narrative:

Air carrier X descending to FL210. Cpr Y level at FL200. Traffic issued to both aircraft. Cpr Y reports air carrier X in sight. Air carrier X turned for sequencing to atl. Air carrier X descended to FL205. Air carrier X advised cpr Y in sight prior to descending. Air carrier X advised they had responded to a TCASII RA. I believe TCASII caused the confliction. There was no other traffic in the vicinity. TCASII should be modified to include assigned altitude so aircraft will not take evasive action from other aircraft ATC has already provided separation from.

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Original NASA ASRS Text

Title: ACR X TCASII RA NON ADHERENCE TO ATC CLRNC UNAUTH DSCNT FROM ASSIGNED ALT HAD LTSS FROM CPR Y. PLTDEV.

Narrative: ACR X DSNDING TO FL210. CPR Y LEVEL AT FL200. TFC ISSUED TO BOTH ACFT. CPR Y RPTS ACR X IN SIGHT. ACR X TURNED FOR SEQUENCING TO ATL. ACR X DSNDED TO FL205. ACR X ADVISED CPR Y IN SIGHT PRIOR TO DSNDING. ACR X ADVISED THEY HAD RESPONDED TO A TCASII RA. I BELIEVE TCASII CAUSED THE CONFLICTION. THERE WAS NO OTHER TFC IN THE VICINITY. TCASII SHOULD BE MODIFIED TO INCLUDE ASSIGNED ALT SO ACFT WILL NOT TAKE EVASIVE ACTION FROM OTHER ACFT ATC HAS ALREADY PROVIDED SEPARATION FROM.

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.