Narrative:

While cruising at FL260, ZAB cleared us to climb to FL290. The clearance was acknowledged and we began our climb. As we were passing FL270, the controller asked us what altitude we were at. We replied that we were climbing through FL275 for FL290. The alert controller immediately told us to maintain FL280 and we complied. The controller further stated that he had not given us a climb clearance. Additionally, he revealed that he had cleared a flight with a similar call sign to FL290 and did not hear our clearance readback. Both the first officer and myself heard our call sign and the clearance to climb to FL290. No other aircraft observed on TCASII while using the 15 NM range. No conflict occurred.

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Original NASA ASRS Text

Title: FLC OF AN MLG RESPONDED TO THE WRONG CALL SIGN RESULTING IN CLBING FROM ASSIGNED ALT.

Narrative: WHILE CRUISING AT FL260, ZAB CLRED US TO CLB TO FL290. THE CLRNC WAS ACKNOWLEDGED AND WE BEGAN OUR CLB. AS WE WERE PASSING FL270, THE CTLR ASKED US WHAT ALT WE WERE AT. WE REPLIED THAT WE WERE CLBING THROUGH FL275 FOR FL290. THE ALERT CTLR IMMEDIATELY TOLD US TO MAINTAIN FL280 AND WE COMPLIED. THE CTLR FURTHER STATED THAT HE HAD NOT GIVEN US A CLB CLRNC. ADDITIONALLY, HE REVEALED THAT HE HAD CLRED A FLT WITH A SIMILAR CALL SIGN TO FL290 AND DID NOT HEAR OUR CLRNC READBACK. BOTH THE FO AND MYSELF HEARD OUR CALL SIGN AND THE CLRNC TO CLB TO FL290. NO OTHER ACFT OBSERVED ON TCASII WHILE USING THE 15 NM RANGE. NO CONFLICT OCCURRED.

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.