Narrative:

We air carrier X were descending to 11000' tracking direct to sfo VOR. At approximately 10 mi northwest we were issued clearance to fly heading 120 and descend to 6000'. The captain acknowledged the clearance and we complied with the instructions. While descending out of 8600' the controller issued us a 090 degree heading and asked if we were at 11000'. The captain told him we were descending out of 8600' to 6000' as clrd. He issued an immediate level off at 8000' as there was medium large transport air carrier Y at 7000' in our 11 O'clock position, and converging. We leveled at 8000' as instructed and passed clear of acy Y. There was some misunderstanding by the controller. I believe he was busy and issued us the clearance which was meant for another aircraft. Having not been in the room with the controller I cannot say why he erred, however he did catch the mistake in time. We also saw medium large transport Y, and obviously would not have hit him. Callback conversation with reporter revealed the following: reporter said that he has not heard any more reference incident and that his PIC did not want to make a big issue of it as the ATC supervisor had told him that the controller involved was pretty upset after incident and it would serve as a good experience for learning on the part of the controller. All 3 flight crew members are positive that controller used their call sign when issuing descent clearance to 6000. There was no danger of collision as they had medium large transport Y in sight for a long period of time and had at least 1000' vertical sep when crossing tracks.

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Original NASA ASRS Text

Title: ACR X RECEIVED DESCENT ALT OF ACR Y ON XING COURSE, BUT CTLR CORRECTED ERROR BEFORE LOSS OF SEPARATION. OPERATIONAL DEVIATION.

Narrative: WE ACR X WERE DSNDING TO 11000' TRACKING DIRECT TO SFO VOR. AT APPROX 10 MI NW WE WERE ISSUED CLRNC TO FLY HDG 120 AND DSND TO 6000'. THE CAPT ACKNOWLEDGED THE CLRNC AND WE COMPLIED WITH THE INSTRUCTIONS. WHILE DSNDING OUT OF 8600' THE CTLR ISSUED US A 090 DEG HDG AND ASKED IF WE WERE AT 11000'. THE CAPT TOLD HIM WE WERE DSNDING OUT OF 8600' TO 6000' AS CLRD. HE ISSUED AN IMMEDIATE LEVEL OFF AT 8000' AS THERE WAS MLG ACR Y AT 7000' IN OUR 11 O'CLOCK POSITION, AND CONVERGING. WE LEVELED AT 8000' AS INSTRUCTED AND PASSED CLEAR OF ACY Y. THERE WAS SOME MISUNDERSTANDING BY THE CTLR. I BELIEVE HE WAS BUSY AND ISSUED US THE CLRNC WHICH WAS MEANT FOR ANOTHER ACFT. HAVING NOT BEEN IN THE ROOM WITH THE CTLR I CANNOT SAY WHY HE ERRED, HOWEVER HE DID CATCH THE MISTAKE IN TIME. WE ALSO SAW MLG Y, AND OBVIOUSLY WOULD NOT HAVE HIT HIM. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR SAID THAT HE HAS NOT HEARD ANY MORE REF INCIDENT AND THAT HIS PIC DID NOT WANT TO MAKE A BIG ISSUE OF IT AS THE ATC SUPVR HAD TOLD HIM THAT THE CTLR INVOLVED WAS PRETTY UPSET AFTER INCIDENT AND IT WOULD SERVE AS A GOOD EXPERIENCE FOR LEARNING ON THE PART OF THE CTLR. ALL 3 FLT CREW MEMBERS ARE POSITIVE THAT CTLR USED THEIR CALL SIGN WHEN ISSUING DSCNT CLRNC TO 6000. THERE WAS NO DANGER OF COLLISION AS THEY HAD MLG Y IN SIGHT FOR A LONG PERIOD OF TIME AND HAD AT LEAST 1000' VERT SEP WHEN XING TRACKS.

Data retrieved from NASA's ASRS site as of August 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.