Narrative:

We were in ind ARTCC airspace navigating between 2 large thunderstorms when we received clearance to descend to FL330. I acknowledged the clearance using our full call sign of air carrier X, since we had been trailing a company flight all the way from florida. Passing through FL340, we received that wonderful question, 'air carrier X, verify FL350.' thus began immediate turns (towards the thunderstorm, of course), further turns and dscnts to avoid traffic and cumulonimbus, and eventually we were on our way at FL310. There were no 'close calls' as far as traffic, but the turns boxing us into the WX created havoc for us and the controller. This is another classic case of similar sounding call signs creating havoc. I am certain that I read back our complete call sign with our clearance, and it was simply not caught. It was not an illogical clearance for us, so it raised no concern. My suspicion is that training may have been going on in our sector, since I recall the original descent clearance coming from a woman, and the later query and subsequent vectors came from a man. Other contributing factors: we should have used greater diligence in listening. ATC should have used caution also (we were only cautioned about similar call signs from 1 controller.) but, the big culprit in my opinion is the use of similar flight numbers by scheduling. This should be avoided diligently by schedulers when at all possible. Supplemental 590331: we began our descent as directed knowing this is common for arrs into chicago. Then we were directed to switch frequencys to another ind center. When checking on the new frequency, the male voice asked us why we were at FL330. We responded that previous center directed us. He responded that was for another aircraft.

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Original NASA ASRS Text

Title: FLT CREW OF B752 DSNDED BELOW CLRED ALT WHEN THEY RESPONDED TO DSCNT CLRNC GIVEN TO FLT WITH SIMILAR SOUNDING CALL SIGN.

Narrative: WE WERE IN IND ARTCC AIRSPACE NAVIGATING BTWN 2 LARGE TSTMS WHEN WE RECEIVED CLRNC TO DSND TO FL330. I ACKNOWLEDGED THE CLRNC USING OUR FULL CALL SIGN OF ACR X, SINCE WE HAD BEEN TRAILING A COMPANY FLT ALL THE WAY FROM FLORIDA. PASSING THROUGH FL340, WE RECEIVED THAT WONDERFUL QUESTION, 'ACR X, VERIFY FL350.' THUS BEGAN IMMEDIATE TURNS (TOWARDS THE TSTM, OF COURSE), FURTHER TURNS AND DSCNTS TO AVOID TFC AND CUMULONIMBUS, AND EVENTUALLY WE WERE ON OUR WAY AT FL310. THERE WERE NO 'CLOSE CALLS' AS FAR AS TFC, BUT THE TURNS BOXING US INTO THE WX CREATED HAVOC FOR US AND THE CTLR. THIS IS ANOTHER CLASSIC CASE OF SIMILAR SOUNDING CALL SIGNS CREATING HAVOC. I AM CERTAIN THAT I READ BACK OUR COMPLETE CALL SIGN WITH OUR CLRNC, AND IT WAS SIMPLY NOT CAUGHT. IT WAS NOT AN ILLOGICAL CLRNC FOR US, SO IT RAISED NO CONCERN. MY SUSPICION IS THAT TRAINING MAY HAVE BEEN GOING ON IN OUR SECTOR, SINCE I RECALL THE ORIGINAL DSCNT CLRNC COMING FROM A WOMAN, AND THE LATER QUERY AND SUBSEQUENT VECTORS CAME FROM A MAN. OTHER CONTRIBUTING FACTORS: WE SHOULD HAVE USED GREATER DILIGENCE IN LISTENING. ATC SHOULD HAVE USED CAUTION ALSO (WE WERE ONLY CAUTIONED ABOUT SIMILAR CALL SIGNS FROM 1 CTLR.) BUT, THE BIG CULPRIT IN MY OPINION IS THE USE OF SIMILAR FLT NUMBERS BY SCHEDULING. THIS SHOULD BE AVOIDED DILIGENTLY BY SCHEDULERS WHEN AT ALL POSSIBLE. SUPPLEMENTAL 590331: WE BEGAN OUR DSCNT AS DIRECTED KNOWING THIS IS COMMON FOR ARRS INTO CHICAGO. THEN WE WERE DIRECTED TO SWITCH FREQS TO ANOTHER IND CTR. WHEN CHKING ON THE NEW FREQ, THE MALE VOICE ASKED US WHY WE WERE AT FL330. WE RESPONDED THAT PREVIOUS CTR DIRECTED US. HE RESPONDED THAT WAS FOR ANOTHER ACFT.

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.