Narrative:

I was first officer on air carrier X231 from anc to ord. Edmonton center cleared us to FL370. Our position was approximately NCA13 between dentu and the pas (yqd). We were switched over to winnipeg center. Edmonton and winnipeg were also controling air carrier Y321. From october 1999 and march 2000, I flew air carrier Y call signs exclusively, including 321. I only flew air carrier X call signs during the month of april. When checking in with winnipeg, I believe I used air carrier Y321 call sign and reported FL370. Winnipeg responded 'you are not cleared to FL370, you are cleared to FL350.' I responded that edmonton had cleared us to FL370 and that was our assigned altitude. We may have had at least 3-4 communications trying to eliminate any confusion. I finally agreed to descend to FL350. I felt uncomfortable and checked TCASII for any conflict with other traffic before commencing descent. Air carrier Y321 was given a frequency change, the same frequency as air carrier X231. Still feeling uncomfortable I checked back with winnipeg and reported leaving FL355 for FL350. Winnipeg said 'air carrier X231 please stand by.' winnipeg stated he spoke with other controllers and we were responding to the incorrect flight number. I immediately responded that may have been the case because I fly both air carrier X231 and air carrier Y321 flight numbers. We stopped our descent at that point and were cleared to climb back to FL370. I apologized for the confusion and was told 'that's ok.' considerations for the future. Change flight numbers so they are not similar along the same routes. Winnipeg's communication was less than 5 by 5.

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Original NASA ASRS Text

Title: SIMILAR CALL SIGN PROB ON N CANADIAN ROUTES BY PLT WHO FLIES 2 DIFFERENT AIRLINE CALL SIGNS.

Narrative: I WAS FO ON ACR X231 FROM ANC TO ORD. EDMONTON CTR CLRED US TO FL370. OUR POS WAS APPROX NCA13 BTWN DENTU AND THE PAS (YQD). WE WERE SWITCHED OVER TO WINNIPEG CTR. EDMONTON AND WINNIPEG WERE ALSO CTLING ACR Y321. FROM OCTOBER 1999 AND MARCH 2000, I FLEW ACR Y CALL SIGNS EXCLUSIVELY, INCLUDING 321. I ONLY FLEW ACR X CALL SIGNS DURING THE MONTH OF APRIL. WHEN CHKING IN WITH WINNIPEG, I BELIEVE I USED ACR Y321 CALL SIGN AND RPTED FL370. WINNIPEG RESPONDED 'YOU ARE NOT CLRED TO FL370, YOU ARE CLRED TO FL350.' I RESPONDED THAT EDMONTON HAD CLRED US TO FL370 AND THAT WAS OUR ASSIGNED ALT. WE MAY HAVE HAD AT LEAST 3-4 COMS TRYING TO ELIMINATE ANY CONFUSION. I FINALLY AGREED TO DSND TO FL350. I FELT UNCOMFORTABLE AND CHKED TCASII FOR ANY CONFLICT WITH OTHER TFC BEFORE COMMENCING DSCNT. ACR Y321 WAS GIVEN A FREQ CHANGE, THE SAME FREQ AS ACR X231. STILL FEELING UNCOMFORTABLE I CHKED BACK WITH WINNIPEG AND RPTED LEAVING FL355 FOR FL350. WINNIPEG SAID 'ACR X231 PLEASE STAND BY.' WINNIPEG STATED HE SPOKE WITH OTHER CTLRS AND WE WERE RESPONDING TO THE INCORRECT FLT NUMBER. I IMMEDIATELY RESPONDED THAT MAY HAVE BEEN THE CASE BECAUSE I FLY BOTH ACR X231 AND ACR Y321 FLT NUMBERS. WE STOPPED OUR DSCNT AT THAT POINT AND WERE CLRED TO CLB BACK TO FL370. I APOLOGIZED FOR THE CONFUSION AND WAS TOLD 'THAT'S OK.' CONSIDERATIONS FOR THE FUTURE. CHANGE FLT NUMBERS SO THEY ARE NOT SIMILAR ALONG THE SAME ROUTES. WINNIPEG'S COM WAS LESS THAN 5 BY 5.

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.