Narrative:

Our flight air carrier (xbby) X was inbound to dtw on the spica arrival at 12000 ft. Approach control issued us a clearance to 'slow to 210 KTS and descend to 7000 ft.' I responded clearly to the clearance using our flight number, and call sign. Nothing further was said to us at that time by ATC. Conditions on the radio were quite busy and it was obvious the controller was busy. My copilot then slowed to 210 KTS and began a descent to 7000 ft. A few mins later ATC told us to, 'turn right to a 300 degree heading at witkr, expect runway 3L ILS.' we acknowledged properly once again. Within a few seconds ATC came back and said, 'change of plans now expect runway 3R ILS.' we again acknowledged appropriately to the clearance. No change in heading at witkr was given for the runway 3R ILS. It was quickly obvious to us that a 300 degree heading at witkr (our previous clearance) was not appropriate to runway 3R downwind. I questioned the controller about this and he replied, 'I'll have a turn for you in a min.' no call sign was used by the controller and I was not satisfied with that, since we were now only 3 mi away from 'witkr.' just as we came up to witkr, I was about ready to again ask the controller about a corrected heading to the downwind, when he came back and said, 'air carrier (xbby) X turn left heading 210 degrees, and, 'I only cleared you to 11' I immediately replied, 'negative, you gave us slow to 210 KTS, descend and maintain 7000 ft.' he said, 'that was for air carrier (xcvy) Y, you took his clearance.' I refrained from any additional radio comment at that point. My copilot and I are positive that we heard, and replied correctly to the descent clearance. We in fact never even heard (air carrier xcvy Y) on frequency. We had been cautioned about (another air carrier) coming on frequency, but never even heard air carrier Y additionally we never ever heard anything about 11000 ft. Furthermore, I never respond using '11,' always one, one thousand.' the term '11' was used by the controller when he first brought the situation to our attention. We landed in dtw without further complication. I then phoned metropolitan TRACON and the gentleman that answered was a supervisor who was already aware of the situation. He had already been 'briefed' by the controller. The supervisor indicated that there was no conflict and everything was fine, but again indicated that we had taken air carrier Y's clearance. I asked the supervisor why the error then was not corrected, because I clearly read back the clearance using our air carrier X call sign. He said, 'do you suppose that air carrier X and air carrier Y both replied simultaneously and the controller did not hear you reply?' I said, that I knew that was possible, but it seemed to me that some sort of squeal would have been heard by the controller and he would have verified who actually was acknowledging the clearance. The supervisor had no reply to that, and simply reiterated the original statement about there not being a conflict and everything was fine.

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Original NASA ASRS Text

Title: AN ACR MLG INBOUND TO DTW TOOK A DSCNT CLRNC AND POSSIBLY A TURN MEANT FOR ANOTHER COMPANY ACFT INBOUND FROM THE S. APCH CTLR CAUGHT THE PROB AND VECTORED THE RPTR'S ACFT IN WITHOUT ANY FURTHER PROBS. CAPT, RPTR COULDN'T LET IT BE AND INSISTS HE WAS NOT IN ERROR.'

Narrative: OUR FLT ACR (XBBY) X WAS INBOUND TO DTW ON THE SPICA ARR AT 12000 FT. APCH CTL ISSUED US A CLRNC TO 'SLOW TO 210 KTS AND DSND TO 7000 FT.' I RESPONDED CLRLY TO THE CLRNC USING OUR FLT NUMBER, AND CALL SIGN. NOTHING FURTHER WAS SAID TO US AT THAT TIME BY ATC. CONDITIONS ON THE RADIO WERE QUITE BUSY AND IT WAS OBVIOUS THE CTLR WAS BUSY. MY COPLT THEN SLOWED TO 210 KTS AND BEGAN A DSCNT TO 7000 FT. A FEW MINS LATER ATC TOLD US TO, 'TURN R TO A 300 DEG HDG AT WITKR, EXPECT RWY 3L ILS.' WE ACKNOWLEDGED PROPERLY ONCE AGAIN. WITHIN A FEW SECONDS ATC CAME BACK AND SAID, 'CHANGE OF PLANS NOW EXPECT RWY 3R ILS.' WE AGAIN ACKNOWLEDGED APPROPRIATELY TO THE CLRNC. NO CHANGE IN HEADING AT WITKR WAS GIVEN FOR THE RWY 3R ILS. IT WAS QUICKLY OBVIOUS TO US THAT A 300 DEG HDG AT WITKR (OUR PREVIOUS CLRNC) WAS NOT APPROPRIATE TO RWY 3R DOWNWIND. I QUESTIONED THE CTLR ABOUT THIS AND HE REPLIED, 'I'LL HAVE A TURN FOR YOU IN A MIN.' NO CALL SIGN WAS USED BY THE CTLR AND I WAS NOT SATISFIED WITH THAT, SINCE WE WERE NOW ONLY 3 MI AWAY FROM 'WITKR.' JUST AS WE CAME UP TO WITKR, I WAS ABOUT READY TO AGAIN ASK THE CTLR ABOUT A CORRECTED HEADING TO THE DOWNWIND, WHEN HE CAME BACK AND SAID, 'ACR (XBBY) X TURN L HDG 210 DEGS, AND, 'I ONLY CLRED YOU TO 11' I IMMEDIATELY REPLIED, 'NEGATIVE, YOU GAVE US SLOW TO 210 KTS, DSND AND MAINTAIN 7000 FT.' HE SAID, 'THAT WAS FOR ACR (XCVY) Y, YOU TOOK HIS CLRNC.' I REFRAINED FROM ANY ADDITIONAL RADIO COMMENT AT THAT POINT. MY COPLT AND I ARE POSITIVE THAT WE HEARD, AND REPLIED CORRECTLY TO THE DSCNT CLRNC. WE IN FACT NEVER EVEN HEARD (ACR XCVY Y) ON FREQ. WE HAD BEEN CAUTIONED ABOUT (ANOTHER ACR) COMING ON FREQ, BUT NEVER EVEN HEARD ACR Y ADDITIONALLY WE NEVER EVER HEARD ANYTHING ABOUT 11000 FT. FURTHERMORE, I NEVER RESPOND USING '11,' ALWAYS ONE, ONE THOUSAND.' THE TERM '11' WAS USED BY THE CTLR WHEN HE FIRST BROUGHT THE SIT TO OUR ATTN. WE LANDED IN DTW WITHOUT FURTHER COMPLICATION. I THEN PHONED METRO TRACON AND THE GENTLEMAN THAT ANSWERED WAS A SUPVR WHO WAS ALREADY AWARE OF THE SIT. HE HAD ALREADY BEEN 'BRIEFED' BY THE CTLR. THE SUPVR INDICATED THAT THERE WAS NO CONFLICT AND EVERYTHING WAS FINE, BUT AGAIN INDICATED THAT WE HAD TAKEN ACR Y'S CLRNC. I ASKED THE SUPVR WHY THE ERROR THEN WAS NOT CORRECTED, BECAUSE I CLRLY READ BACK THE CLRNC USING OUR ACR X CALL SIGN. HE SAID, 'DO YOU SUPPOSE THAT ACR X AND ACR Y BOTH REPLIED SIMULTANEOUSLY AND THE CTLR DID NOT HEAR YOU REPLY?' I SAID, THAT I KNEW THAT WAS POSSIBLE, BUT IT SEEMED TO ME THAT SOME SORT OF SQUEAL WOULD HAVE BEEN HEARD BY THE CTLR AND HE WOULD HAVE VERIFIED WHO ACTUALLY WAS ACKNOWLEDGING THE CLRNC. THE SUPVR HAD NO REPLY TO THAT, AND SIMPLY REITERATED THE ORIGINAL STATEMENT ABOUT THERE NOT BEING A CONFLICT AND EVERYTHING WAS FINE.

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.