AN ACR DC9 OUT OF FL344 AND CLBING TO FL350 WAS ISSUED CLRNC TO BE LEVEL AT FL350 IN 1 MIN DUE TO OPPOSITE DIRECTION TFC AT FL330. AFTER CLOSE TO 2 MINS; THE CTLR OBSERVED THAT THE DC9 HAD NOT REACHED FL350; AND ISSUED VECTOR HEADINGS TO BOTH ACFT IN AN ATTEMPT TO MAINTAIN SEPARATION; HOWEVER; SEPARATION WAS LOST.

Narrative

ACR X (DC9) WAS CLBING OUT OF PIT ENRTE TO MSP AND WAS INITIALLY VECTORED FOR ADDITIONAL TFC. THEN WITH APPROX 600 FT LEFT TO FL350; WAS CLRED TO RESUME NAV DIRECT CRL. ACR Y (B727) ENRTE FROM ORD TO DCA AT FL330 WAS CLRED DIRECT AIR APPROX 30 MI FROM ACR X. AFTER WITNESSING ACR X'S SLUGGISH CLB RATE I TOLD ACR X TO REACH FL350 IN 1 MIN. PLT RESPONDED 'WILCO.' ACR X WAS AT FL344 AT THIS POINT. STILL SLUGGISH IN THE CLB ACR X WAS TURNED FROM APPROX A 328 DEG HDG TO A 010 DEG HDG. ACR Y WAS TURNED FROM APPROX A 130 DEG HDG TO A 200 DEG HDG. AFTER APPROX 1 MIN ACR X WAS AT FL347. IT TOOK ACR X 1 MIN 50 SECONDS TO LEVEL AT FL350. HE LEVELED AT FL347 FOR APPROX 40 SECONDS. AFTER STATING HE WOULD COMPLY WITH THE 1 MIN CLRNC THE PLT NEVER ADVISED HE COULD NOT CLB 600 FT IN 1 MIN. BECAUSE OF THE DENSITY AND COMPLEXITY OF TFC OVER CLEVELAND; HIGH CLB RATES AND DSCNT RATES ARE NEEDED TO SEPARATE TFC. PLTS UNDERSTAND THIS AND CONSISTENTLY ADVISE IF THEY CAN'T MAKE CLRNCS. 600 FT IN 1 MIN ISN'T ASKING A LOT. PLT OF ACR X LATER STATED HE THOUGHT HE COULD MAKE THE CLRNC WHEN ISSUED. HOWEVER; HE NEVER ADVISED UPON REALIZING HE COULD NOT.