Narrative:

In cruise at FL270, abeam tpa on the srq.3 STAR into rsw (air carrier X), I received clearance to cross wounds intersection at 10000 ft. I then repeated the clearance, using my full call sign, and then called ATC -- again, to confirm the crossing altitude. I did this because the STAR indicates: 'expect clearance to cross wounds intersection at 11000 ft.' also, I wanted to confirm the clearance, since we had a 'similar company call sign on frequency' (air carrier Y) whom we had been following since departure from phl. The controller replied 'affirmative' to my request for clearance/altitude confirmation, and assigned a new frequency to us. When I initially contacted the new controller, I stated that we were 'passing through FL230,' since I had begun my descent. The controller then assigned us to 'descend to FL180.' I then informed ATC that we'd begun our descent to comply with wounds intersection at 10000 ft. He seemed surprised and queried 'who gave you that?' when I explained, he stated 'well, you must have received a clearance for another aircraft.' the captain then asked if this was causing a conflict. The controller stated 'no, you're ok.' I believe that this experience reinforces the need for extra vigilance on the radius, especially with 'similar company call sign' on the same frequency.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737 FLT CREW ACCEPTS CLRNC INTENDED FOR OTHER COMPANY ACFT WITH SIMILAR SOUNDING CALL SIGN.

Narrative: IN CRUISE AT FL270, ABEAM TPA ON THE SRQ.3 STAR INTO RSW (ACR X), I RECEIVED CLRNC TO CROSS WOUNDS INTXN AT 10000 FT. I THEN REPEATED THE CLRNC, USING MY FULL CALL SIGN, AND THEN CALLED ATC -- AGAIN, TO CONFIRM THE XING ALT. I DID THIS BECAUSE THE STAR INDICATES: 'EXPECT CLRNC TO CROSS WOUNDS INTXN AT 11000 FT.' ALSO, I WANTED TO CONFIRM THE CLRNC, SINCE WE HAD A 'SIMILAR COMPANY CALL SIGN ON FREQ' (ACR Y) WHOM WE HAD BEEN FOLLOWING SINCE DEP FROM PHL. THE CTLR REPLIED 'AFFIRMATIVE' TO MY REQUEST FOR CLRNC/ALT CONFIRMATION, AND ASSIGNED A NEW FREQ TO US. WHEN I INITIALLY CONTACTED THE NEW CTLR, I STATED THAT WE WERE 'PASSING THROUGH FL230,' SINCE I HAD BEGUN MY DSCNT. THE CTLR THEN ASSIGNED US TO 'DSND TO FL180.' I THEN INFORMED ATC THAT WE'D BEGUN OUR DSCNT TO COMPLY WITH WOUNDS INTXN AT 10000 FT. HE SEEMED SURPRISED AND QUERIED 'WHO GAVE YOU THAT?' WHEN I EXPLAINED, HE STATED 'WELL, YOU MUST HAVE RECEIVED A CLRNC FOR ANOTHER ACFT.' THE CAPT THEN ASKED IF THIS WAS CAUSING A CONFLICT. THE CTLR STATED 'NO, YOU'RE OK.' I BELIEVE THAT THIS EXPERIENCE REINFORCES THE NEED FOR EXTRA VIGILANCE ON THE RADIUS, ESPECIALLY WITH 'SIMILAR COMPANY CALL SIGN' ON THE SAME FREQ.

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.