Narrative:

We had begun our initial descent into pittsburgh, PA, vacating FL370 for FL330. ZDC had given us a right turn for traffic. My first officer was flying and I acknowledged a clearance to expedite our descent to FL240. In the descent, we subsequently received a TCASII TA followed immediately by an RA. We followed the RA, visually picked up the conflicting traffic below us, and then complied with ATC's clearance to climb immediately back to FL330. Reaching pittsburgh, I called the watch desk at ZDC and talked to the supervisor. He said they had just finished reviewing the tapes. He related the following details. There were 7 or 8 aircraft on the frequency with our company's call sign. We were flight X, another was flight Y, which the controller 'intended' to expedite to FL240. The supervisor said that listening to the tape, it 'sounded' like the controller cleared flight Y. My first officer and I both understood that clearance to be for us. Our conflicting traffic was a B737 climbing left to right. The supervisor said we descended to FL315, then climbed back to FL332. He said our vertical separation with the B737 was 1300 ft at 3.1 mi and 1600 ft at 1.2 mi. I asked the supervisor, after listening to the tapes, what action the FAA would take regarding this incident. He said the FAA's conclusion was strictly controller error, since the controller did not correct the situation at the time we acknowledged the clearance to expedite our descent to FL240. Considering contributing factors, I am not aware whether or not the controller was working combined sectors, but it was busy on the frequency. When the conflict arose, there was confusion and seemed to be one or more blocked xmissions. Also, similar call signs make it more difficult for both pilots and controllers to avoid errors. Often, call signs are much more similar than these were. I've often thought a program to eliminate similar call signs would not be difficult to put in place. Supplemental information from acn 575046: we received clearance to descend from FL370 to FL240. We attempted to contact center to verify clearance. The captain and I both understood the clearance and we both understood it was for air carrier Y. Neither the captain nor I raised any questions or thought we needed to clarify the clearance until we saw the developing conflict. At no time was visual contact with the conflicting traffic lost.

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Original NASA ASRS Text

Title: A319 CREW MISHEAR CALL SIGN AND BEGIN DSCNT ON CLRNC INTENDED FOR A B737 COMPANY ACFT.

Narrative: WE HAD BEGUN OUR INITIAL DSCNT INTO PITTSBURGH, PA, VACATING FL370 FOR FL330. ZDC HAD GIVEN US A R TURN FOR TFC. MY FO WAS FLYING AND I ACKNOWLEDGED A CLRNC TO EXPEDITE OUR DSCNT TO FL240. IN THE DSCNT, WE SUBSEQUENTLY RECEIVED A TCASII TA FOLLOWED IMMEDIATELY BY AN RA. WE FOLLOWED THE RA, VISUALLY PICKED UP THE CONFLICTING TFC BELOW US, AND THEN COMPLIED WITH ATC'S CLRNC TO CLB IMMEDIATELY BACK TO FL330. REACHING PITTSBURGH, I CALLED THE WATCH DESK AT ZDC AND TALKED TO THE SUPVR. HE SAID THEY HAD JUST FINISHED REVIEWING THE TAPES. HE RELATED THE FOLLOWING DETAILS. THERE WERE 7 OR 8 ACFT ON THE FREQ WITH OUR COMPANY'S CALL SIGN. WE WERE FLT X, ANOTHER WAS FLT Y, WHICH THE CTLR 'INTENDED' TO EXPEDITE TO FL240. THE SUPVR SAID THAT LISTENING TO THE TAPE, IT 'SOUNDED' LIKE THE CTLR CLRED FLT Y. MY FO AND I BOTH UNDERSTOOD THAT CLRNC TO BE FOR US. OUR CONFLICTING TFC WAS A B737 CLBING L TO R. THE SUPVR SAID WE DSNDED TO FL315, THEN CLBED BACK TO FL332. HE SAID OUR VERT SEPARATION WITH THE B737 WAS 1300 FT AT 3.1 MI AND 1600 FT AT 1.2 MI. I ASKED THE SUPVR, AFTER LISTENING TO THE TAPES, WHAT ACTION THE FAA WOULD TAKE REGARDING THIS INCIDENT. HE SAID THE FAA'S CONCLUSION WAS STRICTLY CTLR ERROR, SINCE THE CTLR DID NOT CORRECT THE SIT AT THE TIME WE ACKNOWLEDGED THE CLRNC TO EXPEDITE OUR DSCNT TO FL240. CONSIDERING CONTRIBUTING FACTORS, I AM NOT AWARE WHETHER OR NOT THE CTLR WAS WORKING COMBINED SECTORS, BUT IT WAS BUSY ON THE FREQ. WHEN THE CONFLICT AROSE, THERE WAS CONFUSION AND SEEMED TO BE ONE OR MORE BLOCKED XMISSIONS. ALSO, SIMILAR CALL SIGNS MAKE IT MORE DIFFICULT FOR BOTH PLTS AND CTLRS TO AVOID ERRORS. OFTEN, CALL SIGNS ARE MUCH MORE SIMILAR THAN THESE WERE. I'VE OFTEN THOUGHT A PROGRAM TO ELIMINATE SIMILAR CALL SIGNS WOULD NOT BE DIFFICULT TO PUT IN PLACE. SUPPLEMENTAL INFO FROM ACN 575046: WE RECEIVED CLRNC TO DSND FROM FL370 TO FL240. WE ATTEMPTED TO CONTACT CTR TO VERIFY CLRNC. THE CAPT AND I BOTH UNDERSTOOD THE CLRNC AND WE BOTH UNDERSTOOD IT WAS FOR ACR Y. NEITHER THE CAPT NOR I RAISED ANY QUESTIONS OR THOUGHT WE NEEDED TO CLARIFY THE CLRNC UNTIL WE SAW THE DEVELOPING CONFLICT. AT NO TIME WAS VISUAL CONTACT WITH THE CONFLICTING TFC LOST.

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.