Narrative:

I received an appreq from what I thought was the danville low sector, asking for lower on the H25. The H25 was located 10 NM northwest of cmi, direct to mqj (100 degree track). FL190 was the assigned altitude in the data block. I approved a descent to FL190. The aest was climbing out of the danville low sector to an assigned altitude of FL210. The aest track was 170 degrees. The aest checked on the frequency out of FL180 to FL210. I stopped the aest at FL200. I then attempted to contact the boiler high sector, as I now thought he had made the appreq, to stop the H25 at FL210. Boiler high did not answer. I made attempts to contact the H25 on my frequencys. Upon communication was established, the H25 was stopped at FL210 and turned to a 180 degree heading. The aest was turned to a 090 degree heading. The H25 could not stop at FL210 in time to avoid loss of separation. An LOA between ZID and ZAU allows aircraft to climb to requested altitude without appreq. Had the aest climb been appreq, this error would have been avoided.

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Original NASA ASRS Text

Title: ZID APPROVES ALT DSCNT FROM ZAU THAT LATER CONFLICTS WITH ANOTHER ZID CLBING ACFT. ZID CTLR CAN'T RECALL WHICH ZAU CTLR EFFECTED COORD.

Narrative: I RECEIVED AN APPREQ FROM WHAT I THOUGHT WAS THE DANVILLE LOW SECTOR, ASKING FOR LOWER ON THE H25. THE H25 WAS LOCATED 10 NM NW OF CMI, DIRECT TO MQJ (100 DEG TRACK). FL190 WAS THE ASSIGNED ALT IN THE DATA BLOCK. I APPROVED A DSCNT TO FL190. THE AEST WAS CLBING OUT OF THE DANVILLE LOW SECTOR TO AN ASSIGNED ALT OF FL210. THE AEST TRACK WAS 170 DEGS. THE AEST CHKED ON THE FREQ OUT OF FL180 TO FL210. I STOPPED THE AEST AT FL200. I THEN ATTEMPTED TO CONTACT THE BOILER HIGH SECTOR, AS I NOW THOUGHT HE HAD MADE THE APPREQ, TO STOP THE H25 AT FL210. BOILER HIGH DID NOT ANSWER. I MADE ATTEMPTS TO CONTACT THE H25 ON MY FREQS. UPON COM WAS ESTABLISHED, THE H25 WAS STOPPED AT FL210 AND TURNED TO A 180 DEG HDG. THE AEST WAS TURNED TO A 090 DEG HDG. THE H25 COULD NOT STOP AT FL210 IN TIME TO AVOID LOSS OF SEPARATION. AN LOA BTWN ZID AND ZAU ALLOWS ACFT TO CLB TO REQUESTED ALT WITHOUT APPREQ. HAD THE AEST CLB BEEN APPREQ, THIS ERROR WOULD HAVE BEEN AVOIDED.

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.