Narrative:

Air carrier X was sbound 20 west of J73 proceeding direct bna flight plan route. Air carrier Y was wbound direct pxv climbing to FL310. Air carrier X was at FL330 and overtaking another aircraft on J73 direct bna by 50 KTS. Air carrier X was turned left heading 090 degrees for vectors to the east of slower traffic. Once clear of traffic, air carrier X was turned right heading 170 degrees direct atl when able. At that time air carrier Y was 15-20 mi in front of air carrier X and about 10 mi south of air carrier X's track proceeding in the opposite direction. I switched an aircraft's frequency and 40 seconds after issuing air carrier X the 170 degree heading, I climbed air carrier Y to FL350. When issuing the climb to air carrier Y, air carrier X was still tracking eastbound. I assumed air carrier X would turn at a normal rate which would put him 10-12 mi behind air carrier Y. However, air carrier X's turn was very sharp. Upon seeing the turn rate I informed air carrier Y to remain at FL310. Air carrier Y had just started his climb and wasn't able to descend back to FL310 in time. Unusual turn rate of air carrier X combined with a slow descent of air carrier Y contributed to this error.

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Original NASA ASRS Text

Title: ACR Y CLB TO OCCUPIED ALT HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: ACR X WAS SBOUND 20 W OF J73 PROCEEDING DIRECT BNA FLT PLAN RTE. ACR Y WAS WBOUND DIRECT PXV CLBING TO FL310. ACR X WAS AT FL330 AND OVERTAKING ANOTHER ACFT ON J73 DIRECT BNA BY 50 KTS. ACR X WAS TURNED L HDG 090 DEGS FOR VECTORS TO THE E OF SLOWER TFC. ONCE CLR OF TFC, ACR X WAS TURNED R HDG 170 DEGS DIRECT ATL WHEN ABLE. AT THAT TIME ACR Y WAS 15-20 MI IN FRONT OF ACR X AND ABOUT 10 MI S OF ACR X'S TRACK PROCEEDING IN THE OPPOSITE DIRECTION. I SWITCHED AN ACFT'S FREQ AND 40 SECONDS AFTER ISSUING ACR X THE 170 DEG HDG, I CLBED ACR Y TO FL350. WHEN ISSUING THE CLB TO ACR Y, ACR X WAS STILL TRACKING EBOUND. I ASSUMED ACR X WOULD TURN AT A NORMAL RATE WHICH WOULD PUT HIM 10-12 MI BEHIND ACR Y. HOWEVER, ACR X'S TURN WAS VERY SHARP. UPON SEEING THE TURN RATE I INFORMED ACR Y TO REMAIN AT FL310. ACR Y HAD JUST STARTED HIS CLB AND WASN'T ABLE TO DSND BACK TO FL310 IN TIME. UNUSUAL TURN RATE OF ACR X COMBINED WITH A SLOW DSCNT OF ACR Y CONTRIBUTED TO THIS ERROR.

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.