ZID CTLR PROVIDING OJT IS LATE IN TAKING THE POS FROM THE DEVELOPMENTAL CTLR AND EXPERIENCED AN OPERROR AT FL310.

Narrative

ACFT X WAS SBOUND VIA J89 ENRTE TO MCO IN LEVEL FLT AT FL310. ACFT Y WAS NBOUND DIRECT IIU AT FL320 LNDG IND. OJT WAS IN PROGRESS WITH DEVELOPMENTAL CTLR WORKING THE RADAR POS. I WAS INSTRUCTING. TFC COMPLEXITY WAS INCREASING. AS DATA BLOCKS BECAME CLUTTERED OVER IIU; THE DEVELOPMENTAL REQUESTED THE AID OF A HDOF CTLR. AS HDOF CTLR WAS JOINING THE SECTOR; DEVELOPMENTAL ISSUED DSCNT CLRNC TO ACFT Y TO FL300. I ADVISED HIM TO BE AWARE OF ACFT X AFTER SEVERAL SECONDS LAPSED WITH NO CORRECTIVE ACTION TAKEN BY THE DEVELOPMENTAL; I TOOK OVER THE FREQ TO ISSUE SEPARATION VECTORS. ACFT X ADVISED DSNDING DUE TO TCAS RA AND ACFT Y ADVISED THEY WERE CLBING. I ISSUED LOWER ALT TO ACFT X AND SHARP TURNS TO BOTH ACFT; BUT STANDARD SEPARATION NOT MAINTAINED. CONTRIBUTING FACTORS WERE RAPID AND SUDDEN INCREASE IN COMPLEXITY; SUPERVISING ALL CTLRS AT THE SECTOR AND THE SUPVR OBSERVING US DIRECTLY; DATA BLOCK CLUTTER AT THE IIU VORTAC CAUSING ME TO MOMENTARILY LOSE TRACK OF ACFT X THEREBY NOT IMMEDIATELY RECOGNIZING THE DIRECTNESS OF THE SITUATION; MY MOMENTARY RELUCTANCE TO TAKE THE SECTOR FROM A DEVELOPMENTAL WHO I FELT WAS NEAR CERTIFICATION AND NEEDED TO 'WORK THROUGH' THE SITUATION; AND AN UNUSUALLY SLOW RATE OF TURN FROM ACFT Y.