Narrative:

While en route to pit, we accepted a clearance to 4000 ft MSL. Before arriving at 4000 ft, however, we thought that we heard the controller clearing us to descend to 3000 ft MSL. The PNF read back the clearance including the call sign. When level at 3000 ft and after being queried by ATC in regard to our altitude, we were informed by the controller that he wanted us at 4000 ft and that he thought we might have responded to a clearance issued to another aircraft with the same company and with a similar flight number. When questioned further the controller said that the readback for the clearance to 3000 ft had been partially garbled and unreadable. Once on the ground we contacted the ATC supervisor by telephone who, after replaying the ATC tape recording, said that the clearance to descend to 3000 ft was indeed meant for another aircraft and that the readback was partially unintelligible. I feel that this situation might have been averted if we had been warned of the presence of company with a similar flight number on the frequency. I also feel that since the readback of the clearance was partially unreadable, this event would have been averted if the controller would have asked for a verification of the readback. Of course paying closer attention to the clrncs that are given to any flight crew would help to avert sits such as this in the future.

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Original NASA ASRS Text

Title: FLC TAKES CLRNC FOR ACFT WITH SIMILAR CALL SIGN.

Narrative: WHILE ENRTE TO PIT, WE ACCEPTED A CLRNC TO 4000 FT MSL. BEFORE ARRIVING AT 4000 FT, HOWEVER, WE THOUGHT THAT WE HEARD THE CTLR CLRING US TO DSND TO 3000 FT MSL. THE PNF READ BACK THE CLRNC INCLUDING THE CALL SIGN. WHEN LEVEL AT 3000 FT AND AFTER BEING QUERIED BY ATC IN REGARD TO OUR ALT, WE WERE INFORMED BY THE CTLR THAT HE WANTED US AT 4000 FT AND THAT HE THOUGHT WE MIGHT HAVE RESPONDED TO A CLRNC ISSUED TO ANOTHER ACFT WITH THE SAME COMPANY AND WITH A SIMILAR FLT NUMBER. WHEN QUESTIONED FURTHER THE CTLR SAID THAT THE READBACK FOR THE CLRNC TO 3000 FT HAD BEEN PARTIALLY GARBLED AND UNREADABLE. ONCE ON THE GND WE CONTACTED THE ATC SUPVR BY TELEPHONE WHO, AFTER REPLAYING THE ATC TAPE RECORDING, SAID THAT THE CLRNC TO DSND TO 3000 FT WAS INDEED MEANT FOR ANOTHER ACFT AND THAT THE READBACK WAS PARTIALLY UNINTELLIGIBLE. I FEEL THAT THIS SIT MIGHT HAVE BEEN AVERTED IF WE HAD BEEN WARNED OF THE PRESENCE OF COMPANY WITH A SIMILAR FLT NUMBER ON THE FREQ. I ALSO FEEL THAT SINCE THE READBACK OF THE CLRNC WAS PARTIALLY UNREADABLE, THIS EVENT WOULD HAVE BEEN AVERTED IF THE CTLR WOULD HAVE ASKED FOR A VERIFICATION OF THE READBACK. OF COURSE PAYING CLOSER ATTN TO THE CLRNCS THAT ARE GIVEN TO ANY FLC WOULD HELP TO AVERT SITS SUCH AS THIS IN THE FUTURE.

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.