Narrative:

Air carrier X departed mco and requested 11000 ft to zqa. I issued 11000 ft and cleared X direct vrb. Aircraft Y was coordinated from R4 controller heading 090 degrees. Y checked on frequency and climbed to 15000 ft. I saw that X and Y were traffic for each other and were already on the land line with R20 about another topic, I coordinated Y at 10000 ft. I believed I had issued Y 10000 ft. I issued traffic to both aircraft as they converged. The traffic issued to X was '1 O'clock 7 mi eastbound climbing to 10000 ft. Traffic to Y was '9 O'clock 3 mi sebound at 11000 ft. Expect higher passing traffic. Both aircraft acknowledged the traffic call. Y continued climb through 10000 ft and I questioned his altitude. I turned X to the left 060 degree heading and Y right to a 180 degree heading to get separation. I also told Y to descend to 10000 ft.

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Original NASA ASRS Text

Title: ACFT Y CLB THROUGH OCCUPIED ALT HAD LTSS FROM ACR X. SYS ERROR.

Narrative: ACR X DEPARTED MCO AND REQUESTED 11000 FT TO ZQA. I ISSUED 11000 FT AND CLRED X DIRECT VRB. ACFT Y WAS COORDINATED FROM R4 CTLR HDG 090 DEGS. Y CHKED ON FREQ AND CLBED TO 15000 FT. I SAW THAT X AND Y WERE TFC FOR EACH OTHER AND WERE ALREADY ON THE LAND LINE WITH R20 ABOUT ANOTHER TOPIC, I COORDINATED Y AT 10000 FT. I BELIEVED I HAD ISSUED Y 10000 FT. I ISSUED TFC TO BOTH ACFT AS THEY CONVERGED. THE TFC ISSUED TO X WAS '1 O'CLOCK 7 MI EBOUND CLBING TO 10000 FT. TFC TO Y WAS '9 O'CLOCK 3 MI SEBOUND AT 11000 FT. EXPECT HIGHER PASSING TFC. BOTH ACFT ACKNOWLEDGED THE TFC CALL. Y CONTINUED CLB THROUGH 10000 FT AND I QUESTIONED HIS ALT. I TURNED X TO THE L 060 DEG HDG AND Y R TO A 180 DEG HDG TO GET SEPARATION. I ALSO TOLD Y TO DSND TO 10000 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.