Narrative:

We were cruising at FL350 msp direct den and had just switched to ZDV. I called in on frequency our altitude and call sign and ZDV acknowledged. Shortly we received a clearance to descend to FL310 and cross keann at 17000'. The controller was difficult to hear on the first part of his transmission and the company name was not as clear as it could have been. I read back the clearance in full followed by our call sign, there was no challenge, so we figured it to be correct. During these communication the first officer was flying was copying down all clearance also and we had no question as to what to do. We also had a jump seat rider who was listening over the speaker and also didn't question anything we heard, said or were doing. During this time we were aware of the controller talking to another air carrier who was behind us at FL350. We also heard a clearance for him to descend to FL310. We started our descent at approximately 120 mi from den out of FL350. At FL340 ZDV asked our altitude, and we replied FL340, descending to 17000' over keann as previously cleared. He said to turn to 280 degrees and level off at FL340. He said that our clearance was for (company name). I thought he was referring to the air carrier behind us. At this time he never did clear up exactly who the clearance was for. Anyway after we just turned to 280 degrees we were again cleared to FL310 and told to turn but left to 210 degrees to intercept the 046 degree den. We did this and continued our descent to 17000'. We got the phone # from ZDV and continued on with no more problems. When we got to our gate I called the supervisor and he was already aware of a problem. He said he had not heard the tapes yet. I said I would call back in about 4 hours from detroit. When I called again he said that we had clearly checked in at FL350 with our call sign and had read back the clearance to 17000' with our call sign. I finally found out all this time the controller thought we were air carrier xyz, and never questioned our readback. As I said before, the first part of his transmission was hard to understand, so we didn't know they were not for us. The supervisor also said the controller in question was temporarily going to be sent back to school to work on his communication and transmission skills because of a general level of proficiency not entirely related to just this one incident. I feel the center is taking the necessary steps to prevent this from happening again.

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Original NASA ASRS Text

Title: CTLR INADVERTENTLY DESCENDED AN ACR THAT WAS INTENDED FOR ANOTHER ACFT.

Narrative: WE WERE CRUISING AT FL350 MSP DIRECT DEN AND HAD JUST SWITCHED TO ZDV. I CALLED IN ON FREQ OUR ALT AND CALL SIGN AND ZDV ACKNOWLEDGED. SHORTLY WE RECEIVED A CLRNC TO DSND TO FL310 AND CROSS KEANN AT 17000'. THE CTLR WAS DIFFICULT TO HEAR ON THE FIRST PART OF HIS XMISSION AND THE COMPANY NAME WAS NOT AS CLEAR AS IT COULD HAVE BEEN. I READ BACK THE CLRNC IN FULL FOLLOWED BY OUR CALL SIGN, THERE WAS NO CHALLENGE, SO WE FIGURED IT TO BE CORRECT. DURING THESE COM THE F/O WAS FLYING WAS COPYING DOWN ALL CLRNC ALSO AND WE HAD NO QUESTION AS TO WHAT TO DO. WE ALSO HAD A JUMP SEAT RIDER WHO WAS LISTENING OVER THE SPEAKER AND ALSO DIDN'T QUESTION ANYTHING WE HEARD, SAID OR WERE DOING. DURING THIS TIME WE WERE AWARE OF THE CTLR TALKING TO ANOTHER ACR WHO WAS BEHIND US AT FL350. WE ALSO HEARD A CLRNC FOR HIM TO DSND TO FL310. WE STARTED OUR DSCNT AT APPROX 120 MI FROM DEN OUT OF FL350. AT FL340 ZDV ASKED OUR ALT, AND WE REPLIED FL340, DSNDING TO 17000' OVER KEANN AS PREVIOUSLY CLRED. HE SAID TO TURN TO 280 DEGS AND LEVEL OFF AT FL340. HE SAID THAT OUR CLRNC WAS FOR (COMPANY NAME). I THOUGHT HE WAS REFERRING TO THE ACR BEHIND US. AT THIS TIME HE NEVER DID CLEAR UP EXACTLY WHO THE CLRNC WAS FOR. ANYWAY AFTER WE JUST TURNED TO 280 DEGS WE WERE AGAIN CLRED TO FL310 AND TOLD TO TURN BUT LEFT TO 210 DEGS TO INTERCEPT THE 046 DEG DEN. WE DID THIS AND CONTINUED OUR DSCNT TO 17000'. WE GOT THE PHONE # FROM ZDV AND CONTINUED ON WITH NO MORE PROBS. WHEN WE GOT TO OUR GATE I CALLED THE SUPVR AND HE WAS ALREADY AWARE OF A PROB. HE SAID HE HAD NOT HEARD THE TAPES YET. I SAID I WOULD CALL BACK IN ABOUT 4 HRS FROM DETROIT. WHEN I CALLED AGAIN HE SAID THAT WE HAD CLEARLY CHKED IN AT FL350 WITH OUR CALL SIGN AND HAD READ BACK THE CLRNC TO 17000' WITH OUR CALL SIGN. I FINALLY FOUND OUT ALL THIS TIME THE CTLR THOUGHT WE WERE ACR XYZ, AND NEVER QUESTIONED OUR READBACK. AS I SAID BEFORE, THE FIRST PART OF HIS XMISSION WAS HARD TO UNDERSTAND, SO WE DIDN'T KNOW THEY WERE NOT FOR US. THE SUPVR ALSO SAID THE CTLR IN QUESTION WAS TEMPORARILY GOING TO BE SENT BACK TO SCHOOL TO WORK ON HIS COM AND XMISSION SKILLS BECAUSE OF A GENERAL LEVEL OF PROFICIENCY NOT ENTIRELY RELATED TO JUST THIS ONE INCIDENT. I FEEL THE CENTER IS TAKING THE NECESSARY STEPS TO PREVENT THIS FROM HAPPENING AGAIN.

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.