Narrative:

We were cleared to FL350 and my first officer read it back. As we reached 28.8 during climb, center said, 'confirm you are level at FL280.' first officer said, 'we were cleared to FL350.' center said, 'return to FL280 and turn left to heading 260.' (we were on a heading of approximately 300 degrees during our climb.) he turned the other aircraft, which was northwest of us, from his southeast heading to a heading of 090 degrees. His altitude was FL290. Center said that they did not lose sep. Contributing factor: our flight # was abc, and during all of our readbacks we pronounced it 'abc.' there was an air carrier #bbc on the previous frequency that we were on when we got the 'clearance to FL350.' (our previous clearance was to FL280.) abc and bbc can sure sound a lot alike. Corrective suggestion: if it was mandatory or if crews would read their call signs as follows: each # clearly stated as '1, 2' for 12, '1, 9-ER' for 19, etc, this could probably not happen again. Another factor was that the controller was not using the airline name in front of the numerical portion of the call sign. Even today, for more than 1/2 of the xmissions I hear for acrs, the facility says only the #, ie, 'abc, climb and maintain FL350.'

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Original NASA ASRS Text

Title: FLT CREW OF LGT READ BACK CLRNC AND BEGAN CLIMB. CENTER ASKED TO CONFIRM LEVEL. RETURNED TO ASSIGNED ALT.

Narrative: WE WERE CLRED TO FL350 AND MY F/O READ IT BACK. AS WE REACHED 28.8 DURING CLB, CENTER SAID, 'CONFIRM YOU ARE LEVEL AT FL280.' F/O SAID, 'WE WERE CLRED TO FL350.' CENTER SAID, 'RETURN TO FL280 AND TURN LEFT TO HDG 260.' (WE WERE ON A HDG OF APPROX 300 DEGS DURING OUR CLB.) HE TURNED THE OTHER ACFT, WHICH WAS NW OF US, FROM HIS SE HDG TO A HDG OF 090 DEGS. HIS ALT WAS FL290. CENTER SAID THAT THEY DID NOT LOSE SEP. CONTRIBUTING FACTOR: OUR FLT # WAS ABC, AND DURING ALL OF OUR READBACKS WE PRONOUNCED IT 'ABC.' THERE WAS AN ACR #BBC ON THE PREVIOUS FREQ THAT WE WERE ON WHEN WE GOT THE 'CLRNC TO FL350.' (OUR PREVIOUS CLRNC WAS TO FL280.) ABC AND BBC CAN SURE SOUND A LOT ALIKE. CORRECTIVE SUGGESTION: IF IT WAS MANDATORY OR IF CREWS WOULD READ THEIR CALL SIGNS AS FOLLOWS: EACH # CLEARLY STATED AS '1, 2' FOR 12, '1, 9-ER' FOR 19, ETC, THIS COULD PROBABLY NOT HAPPEN AGAIN. ANOTHER FACTOR WAS THAT THE CTLR WAS NOT USING THE AIRLINE NAME IN FRONT OF THE NUMERICAL PORTION OF THE CALL SIGN. EVEN TODAY, FOR MORE THAN 1/2 OF THE XMISSIONS I HEAR FOR ACRS, THE FAC SAYS ONLY THE #, IE, 'ABC, CLB AND MAINTAIN FL350.'

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.