Narrative:

Proceeding direct balance on my center at FL180, I was flying (copilot, first officer). Captain was talking to center. I started a PA announcement to the passenger. I heard ATC '...aca descend and maintain 16000 altimeter 30.04' captain read back the clearance and I started descent and finished PA. At 17500' MSL, female voice called check altitude showing 17500'. Captain replied that we received clearance to 16000'. Male voice (excited!) says 'that was for another abca' then center male voice 'abca start your descent now' (no co identification). Center 'air carrier X abca left turn heading 110 degree'. I started turn immediately but did not know what altitude. Lots of confusion with center. 2 male voices and 1 female voice now. We ask and get 17000' and find out air carrier Y abca was on frequency. No one told us nor did we hear any previous xmissions to air carrier Y. We read back air carrier Y's clearance and center did not catch it nor did air carrier Y say anything. Center made several xmissions during the excitement using just 'abca' no company name which added more confusion since there were two abca's in the middle of altitude problem assignments center was making it worse. Air carrier Y abca was handed off ot center 128.7. We were handed off to 128.7. 128.7 did not say anything about similar call signs either. The next sector wash approach 124.2 announced similar call signs. Center was not cautious about full call signs. Even when there was a problem, center still did not use full call signs. Center apologized for the problem on handoff. (We called company to have our flight number changed for future flts).

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Original NASA ASRS Text

Title: MLG REPLIED TO WRONG CALL SIGN AND STARTED DESCENT, CTLR CAUGHT AND TRIED TO CORRECT, BUT CTLR PHRASEOLOGY ONLY CONTINUED TO CONFUSE THE MLG, SUPVR FINALLY STRAIGHTENED IT OUT.

Narrative: PROCEEDING DIRECT BAL ON MY CTR AT FL180, I WAS FLYING (COPLT, F/O). CAPT WAS TALKING TO CTR. I STARTED A PA ANNOUNCEMENT TO THE PAX. I HEARD ATC '...ACA DSND AND MAINTAIN 16000 ALTIMETER 30.04' CAPT READ BACK THE CLRNC AND I STARTED DSNT AND FINISHED PA. AT 17500' MSL, FEMALE VOICE CALLED CHK ALT SHOWING 17500'. CAPT REPLIED THAT WE RECEIVED CLRNC TO 16000'. MALE VOICE (EXCITED!) SAYS 'THAT WAS FOR ANOTHER ABCA' THEN CTR MALE VOICE 'ABCA START YOUR DSNT NOW' (NO CO ID). CTR 'ACR X ABCA L TURN HDG 110 DEG'. I STARTED TURN IMMEDIATELY BUT DID NOT KNOW WHAT ALT. LOTS OF CONFUSION WITH CTR. 2 MALE VOICES AND 1 FEMALE VOICE NOW. WE ASK AND GET 17000' AND FIND OUT ACR Y ABCA WAS ON FREQ. NO ONE TOLD US NOR DID WE HEAR ANY PREVIOUS XMISSIONS TO ACR Y. WE READ BACK ACR Y'S CLRNC AND CTR DID NOT CATCH IT NOR DID ACR Y SAY ANYTHING. CTR MADE SEVERAL XMISSIONS DURING THE EXCITEMENT USING JUST 'ABCA' NO COMPANY NAME WHICH ADDED MORE CONFUSION SINCE THERE WERE TWO ABCA'S IN THE MIDDLE OF ALT PROB ASSIGNMENTS CTR WAS MAKING IT WORSE. ACR Y ABCA WAS HANDED OFF OT CTR 128.7. WE WERE HANDED OFF TO 128.7. 128.7 DID NOT SAY ANYTHING ABOUT SIMILAR CALL SIGNS EITHER. THE NEXT SECTOR WASH APCH 124.2 ANNOUNCED SIMILAR CALL SIGNS. CTR WAS NOT CAUTIOUS ABOUT FULL CALL SIGNS. EVEN WHEN THERE WAS A PROB, CTR STILL DID NOT USE FULL CALL SIGNS. CTR APOLOGIZED FOR THE PROB ON HDOF. (WE CALLED COMPANY TO HAVE OUR FLT NUMBER CHANGED FOR FUTURE FLTS).

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.