Narrative:

The problem arose by having 2 aircraft with the same call #south, distinguishable only by the different company prefixes. To further compound the problem, both aircraft had a destination approximately 35 NM apart, were arriving from the same direction, so therefore routing was over the same arrival fix. Center's workload was heavy at the time. Apparently air carrier Y answered a descent clearance that was intended for air carrier X, which was not noticed by the center controller. At the time we did not realize the clearance was intended for air carrier X (if in fact it was) and we did not acknowledge the clearance with the controller. As I approached my destination, I realized center had not given me clearance to a lower altitude, and I was above normal descent profile altitude, which is not abnormal for the operation into the airport because of the amount of traffic. I had the first officer request a lower altitude from center. We were told by center that he was working on the handoff to approach control. We were not given a descent, but very shortly were assigned a frequency change to approach control. This resulted in being handed off to approach control above their altitude of control. I believe this type of situation could be avoided by: 1) center advising both aircraft of the similarity in call signs. 2) center saying the call sign twice of similar sounding or same # call signs. 3) possibly re-routing 1 aircraft to a different arrival fix. 4) in addition, both aircraft and the controller must be alert to hearback and readback errors.

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Original NASA ASRS Text

Title: ZID FAILED TO COMPLY WITH APCH CTL LETTER OF AGREEMENT. ACR X AT WRONG ALT. ACR X NONADHERENCE TO ATC CLRNC FAILED TO DESCENT. PLT DEVIATION.

Narrative: THE PROB AROSE BY HAVING 2 ACFT WITH THE SAME CALL #S, DISTINGUISHABLE ONLY BY THE DIFFERENT COMPANY PREFIXES. TO FURTHER COMPOUND THE PROB, BOTH ACFT HAD A DEST APPROX 35 NM APART, WERE ARRIVING FROM THE SAME DIRECTION, SO THEREFORE RTING WAS OVER THE SAME ARR FIX. CENTER'S WORKLOAD WAS HVY AT THE TIME. APPARENTLY ACR Y ANSWERED A DSNT CLRNC THAT WAS INTENDED FOR ACR X, WHICH WAS NOT NOTICED BY THE CENTER CTLR. AT THE TIME WE DID NOT REALIZE THE CLRNC WAS INTENDED FOR ACR X (IF IN FACT IT WAS) AND WE DID NOT ACKNOWLEDGE THE CLRNC WITH THE CTLR. AS I APCHED MY DEST, I REALIZED CENTER HAD NOT GIVEN ME CLRNC TO A LOWER ALT, AND I WAS ABOVE NORMAL DSNT PROFILE ALT, WHICH IS NOT ABNORMAL FOR THE OPERATION INTO THE ARPT BECAUSE OF THE AMOUNT OF TFC. I HAD THE F/O REQUEST A LOWER ALT FROM CENTER. WE WERE TOLD BY CENTER THAT HE WAS WORKING ON THE HANDOFF TO APCH CTL. WE WERE NOT GIVEN A DSNT, BUT VERY SHORTLY WERE ASSIGNED A FREQ CHANGE TO APCH CTL. THIS RESULTED IN BEING HANDED OFF TO APCH CTL ABOVE THEIR ALT OF CTL. I BELIEVE THIS TYPE OF SITUATION COULD BE AVOIDED BY: 1) CENTER ADVISING BOTH ACFT OF THE SIMILARITY IN CALL SIGNS. 2) CENTER SAYING THE CALL SIGN TWICE OF SIMILAR SOUNDING OR SAME # CALL SIGNS. 3) POSSIBLY RE-ROUTING 1 ACFT TO A DIFFERENT ARR FIX. 4) IN ADDITION, BOTH ACFT AND THE CTLR MUST BE ALERT TO HEARBACK AND READBACK ERRORS.

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.