Narrative:

As flight abca (with flight adca also on frequency) we first received a clearance to cross 30 NM east of knox at FL250, 300 KIAS. At 35 NM east of knox, we received further clearance to 17000 ft. We (captain) read this back. Then, we were told to maintain 320 KIAS. Several mins passed, and we heard ATC query 'flight adca' regarding their altitude clearance, '...cross bears at 17000 ft.' flight adca said they 'didn't receive the altitude, another aircraft may have read it back.' I said to the captain, 'I bet that was us.' sure enough, ATC queries us to our clearance, which we again read back as 17000 ft. ATC had us stop our descent at FL210 -- too late, as we were already passing through FL193. I arrested descent and climbed back up to FL210. This is a case where our readback was never confirmed. And evidently, the other crew on adca 'missed' the call sign (if, indeed, the controller made no error). I believe ATC called the other flight our name, and the rapid fire communication coupled with similar call signs (and most importantly lack of verification of readback) led to this potential incident.

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Original NASA ASRS Text

Title: A B727 FLC ACCEPTS A CLRNC INTENDED FOR ANOTHER ACR FLT WITH A SIMILAR CALL SIGN. ATC CATCHES THE ERROR AFTER THE WRONG FLT HAS BEEN INTO ITS DSCNT FOR OVER 5000 FT NEAR OXI, IN.

Narrative: AS FLT ABCA (WITH FLT ADCA ALSO ON FREQ) WE FIRST RECEIVED A CLRNC TO CROSS 30 NM E OF KNOX AT FL250, 300 KIAS. AT 35 NM E OF KNOX, WE RECEIVED FURTHER CLRNC TO 17000 FT. WE (CAPT) READ THIS BACK. THEN, WE WERE TOLD TO MAINTAIN 320 KIAS. SEVERAL MINS PASSED, AND WE HEARD ATC QUERY 'FLT ADCA' REGARDING THEIR ALT CLRNC, '...CROSS BEARS AT 17000 FT.' FLT ADCA SAID THEY 'DIDN'T RECEIVE THE ALT, ANOTHER ACFT MAY HAVE READ IT BACK.' I SAID TO THE CAPT, 'I BET THAT WAS US.' SURE ENOUGH, ATC QUERIES US TO OUR CLRNC, WHICH WE AGAIN READ BACK AS 17000 FT. ATC HAD US STOP OUR DSCNT AT FL210 -- TOO LATE, AS WE WERE ALREADY PASSING THROUGH FL193. I ARRESTED DSCNT AND CLBED BACK UP TO FL210. THIS IS A CASE WHERE OUR READBACK WAS NEVER CONFIRMED. AND EVIDENTLY, THE OTHER CREW ON ADCA 'MISSED' THE CALL SIGN (IF, INDEED, THE CTLR MADE NO ERROR). I BELIEVE ATC CALLED THE OTHER FLT OUR NAME, AND THE RAPID FIRE COM COUPLED WITH SIMILAR CALL SIGNS (AND MOST IMPORTANTLY LACK OF VERIFICATION OF READBACK) LED TO THIS POTENTIAL INCIDENT.

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.