Narrative:

Our crew departed st louis on the ozark 3 departure, mcm transition. After being handed off to ZKC, the controller cleared us to climb to FL250. Upon reaching FL250, several mi before mcm VOR, she then cleared us direct dsm VOR, and said to expect higher after passing traffic. Several mins later, approximately XA40 ct, while in IMC, the crew heard the controller clear us to climb to FL260. The captain read back '(our airline call sign and flight number), climbing to FL260.' (the controller did not return to the frequency with a correction. There was also a 'company' aircraft with a similar call sign behind us.) I entered FL260 in the altitude pre-select, the captain confirmed it, and I began the climb. The controller then came back to us, asking here we were going. The captain reminded her that she had cleared us to FL260. The controller said at that time that we were not cleared to FL260 and to return to FL250.

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Original NASA ASRS Text

Title: E140 OFF STL CLBS TO FL260, BUT LEARNS CLRNC WAS FOR COMPANY WITH SIMILAR CALL SIGN.

Narrative: OUR CREW DEPARTED ST LOUIS ON THE OZARK 3 DEP, MCM TRANSITION. AFTER BEING HANDED OFF TO ZKC, THE CTLR CLRED US TO CLB TO FL250. UPON REACHING FL250, SEVERAL MI BEFORE MCM VOR, SHE THEN CLRED US DIRECT DSM VOR, AND SAID TO EXPECT HIGHER AFTER PASSING TFC. SEVERAL MINS LATER, APPROX XA40 CT, WHILE IN IMC, THE CREW HEARD THE CTLR CLR US TO CLB TO FL260. THE CAPT READ BACK '(OUR AIRLINE CALL SIGN AND FLT NUMBER), CLBING TO FL260.' (THE CTLR DID NOT RETURN TO THE FREQ WITH A CORRECTION. THERE WAS ALSO A 'COMPANY' ACFT WITH A SIMILAR CALL SIGN BEHIND US.) I ENTERED FL260 IN THE ALT PRE-SELECT, THE CAPT CONFIRMED IT, AND I BEGAN THE CLB. THE CTLR THEN CAME BACK TO US, ASKING HERE WE WERE GOING. THE CAPT REMINDED HER THAT SHE HAD CLRED US TO FL260. THE CTLR SAID AT THAT TIME THAT WE WERE NOT CLRED TO FL260 AND TO RETURN TO FL250.

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.