Narrative:

I was working the macon hi sector in ZTL. The workload was heavy, approximately 16 aircraft on frequency with an additional 8 data blocks on the scope. The complexity was moderate. At the time of the error I had just finished solving 2 separate conflictions that were taking place on opposite ends of my sector. An adjacent sector flashed a handoff to me on air carrier X departing bhm requesting FL330 eastbound. I already had 6 aircraft at FL330 within 1 1/2 mi of each other on converging rtes approaching atl. I called the sector who was flashing me X and stated 'stop air carrier X at FL290 for his final.' the controller said ok. Since X would be stopped at FL290 he would not be traffic for anybody in my sector except for an aircraft I had northbound at FL280, which I was aware of. I returned my focus on separating my traffic at FL330. Approximately 2 mins after I called requesting air carrier X, X checked on my frequency climbing to FL330. I did not catch this. I thought he checked on climbing to FL290. About 15 mi east of atl I turned X 15 degrees left to shortcut his route and ensure he stayed separated from my northbound traffic at FL280. As X reached FL290 he had traffic Y about 11 O'clock, 2 mi northbound at FL310. No traffic was issued. The next computer update the mode C indicated FL295, I immediately asked X 'verify climbing to FL290.' he stated no, we're climbing to FL330, would you like us to descend to FL290. I said affirmative, maintain FL290. Conflict alert activated after I finished that transmission. Not detecting that, checked on climbing to FL330, was 1 reason for the error and I take responsibility for that, but I also know that if my initial instructions had been complied with by my fellow controller that this error would not have happened.

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Original NASA ASRS Text

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

Narrative: I WAS WORKING THE MACON HI SECTOR IN ZTL. THE WORKLOAD WAS HVY, APPROX 16 ACFT ON FREQ WITH AN ADDITIONAL 8 DATA BLOCKS ON THE SCOPE. THE COMPLEXITY WAS MODERATE. AT THE TIME OF THE ERROR I HAD JUST FINISHED SOLVING 2 SEPARATE CONFLICTIONS THAT WERE TAKING PLACE ON OPPOSITE ENDS OF MY SECTOR. AN ADJACENT SECTOR FLASHED A HDOF TO ME ON ACR X DEPARTING BHM REQUESTING FL330 EBOUND. I ALREADY HAD 6 ACFT AT FL330 WITHIN 1 1/2 MI OF EACH OTHER ON CONVERGING RTES APCHING ATL. I CALLED THE SECTOR WHO WAS FLASHING ME X AND STATED 'STOP ACR X AT FL290 FOR HIS FINAL.' THE CTLR SAID OK. SINCE X WOULD BE STOPPED AT FL290 HE WOULD NOT BE TFC FOR ANYBODY IN MY SECTOR EXCEPT FOR AN ACFT I HAD NBOUND AT FL280, WHICH I WAS AWARE OF. I RETURNED MY FOCUS ON SEPARATING MY TFC AT FL330. APPROX 2 MINS AFTER I CALLED REQUESTING ACR X, X CHKED ON MY FREQ CLBING TO FL330. I DID NOT CATCH THIS. I THOUGHT HE CHKED ON CLBING TO FL290. ABOUT 15 MI E OF ATL I TURNED X 15 DEGS L TO SHORTCUT HIS RTE AND ENSURE HE STAYED SEPARATED FROM MY NBOUND TFC AT FL280. AS X REACHED FL290 HE HAD TFC Y ABOUT 11 O'CLOCK, 2 MI NBOUND AT FL310. NO TFC WAS ISSUED. THE NEXT COMPUTER UPDATE THE MODE C INDICATED FL295, I IMMEDIATELY ASKED X 'VERIFY CLBING TO FL290.' HE STATED NO, WE'RE CLBING TO FL330, WOULD YOU LIKE US TO DSND TO FL290. I SAID AFFIRMATIVE, MAINTAIN FL290. CONFLICT ALERT ACTIVATED AFTER I FINISHED THAT XMISSION. NOT DETECTING THAT, CHKED ON CLBING TO FL330, WAS 1 REASON FOR THE ERROR AND I TAKE RESPONSIBILITY FOR THAT, BUT I ALSO KNOW THAT IF MY INITIAL INSTRUCTIONS HAD BEEN COMPLIED WITH BY MY FELLOW CTLR THAT THIS ERROR WOULD NOT HAVE HAPPENED.

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.