Narrative:

Very busy time of day for this sector: overflts crossing, sequencing for 2 major airports, climbing departure traffic to requested final altitudes, descending arriving aircraft to the 'low' sectors. An unusual holding/circling was going between 2 sectors by a military E3, which was talking to the 'other' sector. The E3's previous circuits took it over a major departure airway for climbing aircraft and crossing the en route traffic. The E3 had previously made 30 mi or more circuits at FL290. I had 2 aircraft stopped at FL280, which when I thought the E3 was headed away for a large circuit, I climbed to an altitude above the E3's altitude. Because of the E3's changing the normal flow patterns of traffic, I was distraction by extra coordination and not being able to move the traffic as quickly as normal. The E3 made a very tight turn on this last particular circuit. The leader line was not caught up with the actual flight path and the conflict alert did not go off. I overlooked the histories of the aircraft and did not realize he was on a conflicting flight path. When I was made aware of the conflict, I told the climbing aircraft to stop the climb, then descend to the original altitude of FL280. As far as I know, the TCASII did not go off in the climbing aircraft. I was controling on where I expected the aircraft to be, and to be doing, not on what it had done. I would protect circling aircraft like deviating aircraft with altitude separation, until no chance of either aircraft turning into the other's flight path in future circumstances. Supplemental information from acn 527337: as radar associate, I was doing pointouts, and coordination, and I heard a pilot say 'what are the intentions of the aircraft at our 12 O'clock position?' I scanned for the situation and radar controller stopped the aircraft's climb and descended it back down to FL280.

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Original NASA ASRS Text

Title: ZOB ARTCC RADAR CTLR DID NOT EXPECT AN E3 ACFT MAKING LARGE CIRCLES AT FL290 TO SHORTEN A TURN AND CONFLICT WITH A CLBING ACR.

Narrative: VERY BUSY TIME OF DAY FOR THIS SECTOR: OVERFLTS XING, SEQUENCING FOR 2 MAJOR ARPTS, CLBING DEP TFC TO REQUESTED FINAL ALTS, DSNDING ARRIVING ACFT TO THE 'LOW' SECTORS. AN UNUSUAL HOLDING/CIRCLING WAS GOING BTWN 2 SECTORS BY A MIL E3, WHICH WAS TALKING TO THE 'OTHER' SECTOR. THE E3'S PREVIOUS CIRCUITS TOOK IT OVER A MAJOR DEP AIRWAY FOR CLBING ACFT AND XING THE ENRTE TFC. THE E3 HAD PREVIOUSLY MADE 30 MI OR MORE CIRCUITS AT FL290. I HAD 2 ACFT STOPPED AT FL280, WHICH WHEN I THOUGHT THE E3 WAS HEADED AWAY FOR A LARGE CIRCUIT, I CLBED TO AN ALT ABOVE THE E3'S ALT. BECAUSE OF THE E3'S CHANGING THE NORMAL FLOW PATTERNS OF TFC, I WAS DISTR BY EXTRA COORD AND NOT BEING ABLE TO MOVE THE TFC AS QUICKLY AS NORMAL. THE E3 MADE A VERY TIGHT TURN ON THIS LAST PARTICULAR CIRCUIT. THE LEADER LINE WAS NOT CAUGHT UP WITH THE ACTUAL FLT PATH AND THE CONFLICT ALERT DID NOT GO OFF. I OVERLOOKED THE HISTORIES OF THE ACFT AND DID NOT REALIZE HE WAS ON A CONFLICTING FLT PATH. WHEN I WAS MADE AWARE OF THE CONFLICT, I TOLD THE CLBING ACFT TO STOP THE CLB, THEN DSND TO THE ORIGINAL ALT OF FL280. AS FAR AS I KNOW, THE TCASII DID NOT GO OFF IN THE CLBING ACFT. I WAS CTLING ON WHERE I EXPECTED THE ACFT TO BE, AND TO BE DOING, NOT ON WHAT IT HAD DONE. I WOULD PROTECT CIRCLING ACFT LIKE DEVIATING ACFT WITH ALT SEPARATION, UNTIL NO CHANCE OF EITHER ACFT TURNING INTO THE OTHER'S FLT PATH IN FUTURE CIRCUMSTANCES. SUPPLEMENTAL INFO FROM ACN 527337: AS RADAR ASSOCIATE, I WAS DOING POINTOUTS, AND COORD, AND I HEARD A PLT SAY 'WHAT ARE THE INTENTIONS OF THE ACFT AT OUR 12 O'CLOCK POS?' I SCANNED FOR THE SIT AND RADAR CTLR STOPPED THE ACFT'S CLB AND DSNDED IT BACK DOWN TO FL280.

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.