Narrative:

As the final controller; I accepted a radar handoff from the feeder sector; where training was being conducted and had to issue a corrective downwind heading and did to air carrier Y who acknowledged; turn 10 degrees to the left and descend to 10000 ft. While monitoring and recognizing that air carrier Y had to be turned further to the east; I transposed the call sign to air carrier X and issued a turn left heading to 120 degrees immediately because of a higher; fast approaching MVA (11000 ft). Air carrier X read back the clearance which I failed to catch because I know I was so locked into and looking at air carrier Y; that when I did realize what had happened corrective actions were taken but the loss of separation was occurring.

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Original NASA ASRS Text

Title: S56 CTLR EXPERIENCED OPERROR AT 10;000' WHILE VECTORING FINAL TFC WHEN TRANSPOSING SIMILAR CALL SIGNS.

Narrative: AS THE FINAL CTLR; I ACCEPTED A RADAR HDOF FROM THE FEEDER SECTOR; WHERE TRAINING WAS BEING CONDUCTED AND HAD TO ISSUE A CORRECTIVE DOWNWIND HDG AND DID TO ACR Y WHO ACKNOWLEDGED; TURN 10 DEGS TO THE L AND DSND TO 10000 FT. WHILE MONITORING AND RECOGNIZING THAT ACR Y HAD TO BE TURNED FURTHER TO THE E; I TRANSPOSED THE CALL SIGN TO ACR X AND ISSUED A TURN L HDG TO 120 DEGS IMMEDIATELY BECAUSE OF A HIGHER; FAST APCHING MVA (11000 FT). ACR X READ BACK THE CLRNC WHICH I FAILED TO CATCH BECAUSE I KNOW I WAS SO LOCKED INTO AND LOOKING AT ACR Y; THAT WHEN I DID REALIZE WHAT HAD HAPPENED CORRECTIVE ACTIONS WERE TAKEN BUT THE LOSS OF SEPARATION WAS OCCURRING.

Data retrieved from NASA's ASRS site as of January 2009 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.