Narrative:

B737 X traffic was given a heading to parallel the DC9 Y so that the B737 could descend through the altitude of the DC9 and then turn on course. The B737 was given a clearance when reaching an altitude clear of the DC9 to turn on course. From the readback we received, the pilot understood this but in reality the B737 pilot thought he was cleared on course before separation was attained. Supplemental information from acn 457403: descent on waken arrival, ZOB cleared us to descend to 16000 ft. We were then cleared off arrival with a 010 degree heading and continued descent. We then descended through FL180. We were given a partially blocked clearance to return back direct wakem. The captain informed - we only received back to direct wakem and we missed the first part due to a blocked transmission. The controller replied direct wakem clearance correct. The captain read back direct wakem and I turned the aircraft back 30 or 40 degrees back to wakem and continued the descent to 16000 ft. A min or so later, the controller asked us to verify the 010 degree heading. The captain informed her we were direct wakem as cleared by her. She gave us an immediate left turn back to a 010 degree heading. She informed us the clearance was direct wakem reaching 16000 ft, a clearance that we never heard or read back. I observed a DC9, 800-900 ft off our right wing at 3-4 mi, obviously the traffic we were vectored away and cleared below. After landing, the captain called ZOB. They had already pulled the tapes and informed the captain that the controller was at fault for not giving us proper instructions.

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Original NASA ASRS Text

Title: ZOB CTLR, PROVIDING OJT, ISSUES B737 CONDITIONAL CLRNC THAT WAS NOT COMPLIED WITH, RESULTING IN A CONFLICT WITH PARALLEL DC9 TFC.

Narrative: B737 X TFC WAS GIVEN A HDG TO PARALLEL THE DC9 Y SO THAT THE B737 COULD DSND THROUGH THE ALT OF THE DC9 AND THEN TURN ON COURSE. THE B737 WAS GIVEN A CLRNC WHEN REACHING AN ALT CLR OF THE DC9 TO TURN ON COURSE. FROM THE READBACK WE RECEIVED, THE PLT UNDERSTOOD THIS BUT IN REALITY THE B737 PLT THOUGHT HE WAS CLRED ON COURSE BEFORE SEPARATION WAS ATTAINED. SUPPLEMENTAL INFO FROM ACN 457403: DSCNT ON WAKEN ARR, ZOB CLRED US TO DSND TO 16000 FT. WE WERE THEN CLRED OFF ARR WITH A 010 DEG HDG AND CONTINUED DSCNT. WE THEN DSNDED THROUGH FL180. WE WERE GIVEN A PARTIALLY BLOCKED CLRNC TO RETURN BACK DIRECT WAKEM. THE CAPT INFORMED - WE ONLY RECEIVED BACK TO DIRECT WAKEM AND WE MISSED THE FIRST PART DUE TO A BLOCKED XMISSION. THE CTLR REPLIED DIRECT WAKEM CLRNC CORRECT. THE CAPT READ BACK DIRECT WAKEM AND I TURNED THE ACFT BACK 30 OR 40 DEGS BACK TO WAKEM AND CONTINUED THE DSCNT TO 16000 FT. A MIN OR SO LATER, THE CTLR ASKED US TO VERIFY THE 010 DEG HDG. THE CAPT INFORMED HER WE WERE DIRECT WAKEM AS CLRED BY HER. SHE GAVE US AN IMMEDIATE L TURN BACK TO A 010 DEG HDG. SHE INFORMED US THE CLRNC WAS DIRECT WAKEM REACHING 16000 FT, A CLRNC THAT WE NEVER HEARD OR READ BACK. I OBSERVED A DC9, 800-900 FT OFF OUR R WING AT 3-4 MI, OBVIOUSLY THE TFC WE WERE VECTORED AWAY AND CLRED BELOW. AFTER LNDG, THE CAPT CALLED ZOB. THEY HAD ALREADY PULLED THE TAPES AND INFORMED THE CAPT THAT THE CTLR WAS AT FAULT FOR NOT GIVING US PROPER INSTRUCTIONS.

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.