Narrative:

Flight bca (my flight) was cleared to 17000'. We acknowledged with call sign. There may have been a frequency change at this point. I heard center say gca expedite through (or to) 17000'. Someone said, 'we were only cleared to 17000',' (no call sign). Center said, 'roger bca. Cleared to FL230, expedite through 17000'.' my first officer acknowledged 'bca cleared to FL230, expedite through 17000'.' I picked up the rate of climb (we were passing about 16000'). Passing 17400' center said, 'bca maintain 17000'.' we acknowledged and center told us we had been cleared only to 17000', and that there was an air carrier gca on frequency. We commented by way of apology that he had not alerted us to the similar call signs and made some remark about listening closely. My first officer replied that he had cleared us to FL230, and that we had read it back. Gca called and informed center that they had been cleared to 17000'. Center then cleared bca to FL230 to expedite out of 17000'. I can assure you we did so (having returned previously to 17000') very expeditiously while keeping heads up for traffic. This appears to have been a case of controller mishearing a readback, compounded by a comment which had not included a call sign. Then, it is my guess, that the controller swapped air carrier bca and same air carrier gca call signs, and issued clearance accordingly. Conflict may have been that both flts were now at 17000'. This incident may or may not have had serious potential, but it points out the need to always affix a complete call sign to all transmission, to preclude miscom, as well as to provide recorded evidence in the event of conflict and/or violation.

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Original NASA ASRS Text

Title: CTLR CONFUSION AND HEARBACK PROBLEM WITH SIMILAR A/N AND SAME COMPANY.

Narrative: FLT BCA (MY FLT) WAS CLRED TO 17000'. WE ACKNOWLEDGED WITH CALL SIGN. THERE MAY HAVE BEEN A FREQ CHANGE AT THIS POINT. I HEARD CENTER SAY GCA EXPEDITE THROUGH (OR TO) 17000'. SOMEONE SAID, 'WE WERE ONLY CLRED TO 17000',' (NO CALL SIGN). CENTER SAID, 'ROGER BCA. CLRED TO FL230, EXPEDITE THROUGH 17000'.' MY F/O ACKNOWLEDGED 'BCA CLRED TO FL230, EXPEDITE THROUGH 17000'.' I PICKED UP THE RATE OF CLB (WE WERE PASSING ABOUT 16000'). PASSING 17400' CENTER SAID, 'BCA MAINTAIN 17000'.' WE ACKNOWLEDGED AND CENTER TOLD US WE HAD BEEN CLRED ONLY TO 17000', AND THAT THERE WAS AN ACR GCA ON FREQ. WE COMMENTED BY WAY OF APOLOGY THAT HE HAD NOT ALERTED US TO THE SIMILAR CALL SIGNS AND MADE SOME REMARK ABOUT LISTENING CLOSELY. MY F/O REPLIED THAT HE HAD CLRED US TO FL230, AND THAT WE HAD READ IT BACK. GCA CALLED AND INFORMED CENTER THAT THEY HAD BEEN CLRED TO 17000'. CENTER THEN CLRED BCA TO FL230 TO EXPEDITE OUT OF 17000'. I CAN ASSURE YOU WE DID SO (HAVING RETURNED PREVIOUSLY TO 17000') VERY EXPEDITIOUSLY WHILE KEEPING HEADS UP FOR TFC. THIS APPEARS TO HAVE BEEN A CASE OF CTLR MISHEARING A READBACK, COMPOUNDED BY A COMMENT WHICH HAD NOT INCLUDED A CALL SIGN. THEN, IT IS MY GUESS, THAT THE CTLR SWAPPED ACR BCA AND SAME ACR GCA CALL SIGNS, AND ISSUED CLRNC ACCORDINGLY. CONFLICT MAY HAVE BEEN THAT BOTH FLTS WERE NOW AT 17000'. THIS INCIDENT MAY OR MAY NOT HAVE HAD SERIOUS POTENTIAL, BUT IT POINTS OUT THE NEED TO ALWAYS AFFIX A COMPLETE CALL SIGN TO ALL XMISSION, TO PRECLUDE MISCOM, AS WELL AS TO PROVIDE RECORDED EVIDENCE IN THE EVENT OF CONFLICT AND/OR VIOLATION.

Data retrieved from NASA's ASRS site as of August 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.