Narrative:

Air carrier X and air carrier Y were converging at FL310. I issued a 25 degree turn for air carrier Y. It wasn't enough and I issued an additional 20 degree to air carrier Y. I then instructed air carrier X to maintain present heading. Following this I descended air carrier Y immediately to FL290. Eventually I turned air carrier X 20 degrees right immediately. Separation was lost at 4.4 mi and 1500 ft.

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Original NASA ASRS Text

Title: OPERROR. LTSS BTWN CONVERGING B757 AND MD80 AT THE SAME ALT.

Narrative: ACR X AND ACR Y WERE CONVERGING AT FL310. I ISSUED A 25 DEG TURN FOR ACR Y. IT WASN'T ENOUGH AND I ISSUED AN ADDITIONAL 20 DEG TO ACR Y. I THEN INSTRUCTED ACR X TO MAINTAIN PRESENT HDG. FOLLOWING THIS I DSNDED ACR Y IMMEDIATELY TO FL290. EVENTUALLY I TURNED ACR X 20 DEGS R IMMEDIATELY. SEPARATION WAS LOST AT 4.4 MI AND 1500 FT.

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.