Narrative:

We had reported for duty at XA30 for the last day of a 3 day trip. On the final leg of the day, we were flight XY0 following along the mosey 5 STAR into cvg. There was also a company flight XY8 apparently just ahead of us in the traffic flow and on the same ATC center frequency. ATC did not notify us of aircraft with similar sounding call signs on the frequency. The confusion began when ATC issued a clearance for what we heard as XY0 to proceed direct to abb VOR. We acknowledged/read back the clearance using our XY0 call sign. But no sooner had we typed direct abb into the FMS and begun to turn in that direction than ATC called and told XY0 to turn 30 degrees left for the sequence. So I once again read back the clearance using our XY0 call sign and advised ATC what that heading would be since we were presently in a turn. The captain and I thought that receiving these 2 contradictory clrncs in rapid succession was a little odd, but we had no concrete reason to suspect that something was amiss. So, we complied and did not query. In hindsight we should have queried ATC aid, given similar circumstances in the future, I will. Anyhow, shortly thereafter, ATC called XY8 and asked if they were direct abb. They said no because they thought that 'direct abb' had been for XY0 since we had acknowledged the clearance. ATC informed XY8 that they were the ones supposed to be going direct abb. It seems interesting that, supposing ATC did clear XY8 to zbb, we heard the number as XY0 and ATC didn't catch XY0 in the readback. And flight XY8 on the frequency remained silent as we supposedly answered their clearance. It was truly difficult to discern XY0 versus XY8 as evidenced later when we were both on approach frequency. Approach issued a clearance to XY8 and XY8 read it back by saying '...X-Y-8.' and the controller still called back to verify that XY8 had acknowledged.

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Original NASA ASRS Text

Title: A CL65 FLC RPT ON CONFUSION STEMMING FROM 2 SIMILAR SOUNDING CALL SIGNS AND THE PROBS WITH ARR PROCS INTO CVG, OH.

Narrative: WE HAD RPTED FOR DUTY AT XA30 FOR THE LAST DAY OF A 3 DAY TRIP. ON THE FINAL LEG OF THE DAY, WE WERE FLT XY0 FOLLOWING ALONG THE MOSEY 5 STAR INTO CVG. THERE WAS ALSO A COMPANY FLT XY8 APPARENTLY JUST AHEAD OF US IN THE TFC FLOW AND ON THE SAME ATC CTR FREQ. ATC DID NOT NOTIFY US OF ACFT WITH SIMILAR SOUNDING CALL SIGNS ON THE FREQ. THE CONFUSION BEGAN WHEN ATC ISSUED A CLRNC FOR WHAT WE HEARD AS XY0 TO PROCEED DIRECT TO ABB VOR. WE ACKNOWLEDGED/READ BACK THE CLRNC USING OUR XY0 CALL SIGN. BUT NO SOONER HAD WE TYPED DIRECT ABB INTO THE FMS AND BEGUN TO TURN IN THAT DIRECTION THAN ATC CALLED AND TOLD XY0 TO TURN 30 DEGS L FOR THE SEQUENCE. SO I ONCE AGAIN READ BACK THE CLRNC USING OUR XY0 CALL SIGN AND ADVISED ATC WHAT THAT HDG WOULD BE SINCE WE WERE PRESENTLY IN A TURN. THE CAPT AND I THOUGHT THAT RECEIVING THESE 2 CONTRADICTORY CLRNCS IN RAPID SUCCESSION WAS A LITTLE ODD, BUT WE HAD NO CONCRETE REASON TO SUSPECT THAT SOMETHING WAS AMISS. SO, WE COMPLIED AND DID NOT QUERY. IN HINDSIGHT WE SHOULD HAVE QUERIED ATC AID, GIVEN SIMILAR CIRCUMSTANCES IN THE FUTURE, I WILL. ANYHOW, SHORTLY THEREAFTER, ATC CALLED XY8 AND ASKED IF THEY WERE DIRECT ABB. THEY SAID NO BECAUSE THEY THOUGHT THAT 'DIRECT ABB' HAD BEEN FOR XY0 SINCE WE HAD ACKNOWLEDGED THE CLRNC. ATC INFORMED XY8 THAT THEY WERE THE ONES SUPPOSED TO BE GOING DIRECT ABB. IT SEEMS INTERESTING THAT, SUPPOSING ATC DID CLR XY8 TO ZBB, WE HEARD THE NUMBER AS XY0 AND ATC DIDN'T CATCH XY0 IN THE READBACK. AND FLT XY8 ON THE FREQ REMAINED SILENT AS WE SUPPOSEDLY ANSWERED THEIR CLRNC. IT WAS TRULY DIFFICULT TO DISCERN XY0 VERSUS XY8 AS EVIDENCED LATER WHEN WE WERE BOTH ON APCH FREQ. APCH ISSUED A CLRNC TO XY8 AND XY8 READ IT BACK BY SAYING '...X-Y-8.' AND THE CTLR STILL CALLED BACK TO VERIFY THAT XY8 HAD ACKNOWLEDGED.

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.