Narrative:

Our flight X (ihh) either next intrail or second to a company west (iih) arriving mia area from southeast with identical routing in this phase, identical clrncs, etc. Great possibility of confusion because of similar flight numbers. Our flight X cleared to 6000' and subsequently to 3000' with heading change after passing bsy VOR to 280 degrees. Foreign air carrier Y was outbnd from miami at 5000', 180 degree heading. Appears to be classic example of similar sounding flight numbers, radio speech and aircraft operating in same area on different ATC frequencys (inbound 120.5, outbnd 118.1). Callback conversation with reporter revealed the following: reporter was first officer on air carrier X. Says PIC did have telephone review with ATC after landing, and later after tapes were played. Controller had meant descent clearance for company trip west who was well ahead of X and clear of departure path of Y. However, controller used wrong call sign in giving descent clearance. Reporter says he thought it unusual that they would be cleared to 3000' so soon, but did not question clearance until they saw air carrier Y on crossing course at 5000'. Reporter did readback descent clearance, and did not hear company west acknowledge same clearance, but says they may have blocked each other in readback. Reporter aircraft leveled off about 5800' to pass over Y. Air carrier Y had just been pointed out as traffic for X. X and Y were on partyline, but controller never did advise that there were similar call signs on frequency.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN 2 ACR ACFT. SIMILAR CALL SIGN PROBLEM. OPERATIONAL ERROR.

Narrative: OUR FLT X (IHH) EITHER NEXT INTRAIL OR SECOND TO A COMPANY W (IIH) ARRIVING MIA AREA FROM SE WITH IDENTICAL ROUTING IN THIS PHASE, IDENTICAL CLRNCS, ETC. GREAT POSSIBILITY OF CONFUSION BECAUSE OF SIMILAR FLT NUMBERS. OUR FLT X CLRED TO 6000' AND SUBSEQUENTLY TO 3000' WITH HDG CHANGE AFTER PASSING BSY VOR TO 280 DEGS. FOREIGN ACR Y WAS OUTBND FROM MIAMI AT 5000', 180 DEG HDG. APPEARS TO BE CLASSIC EXAMPLE OF SIMILAR SOUNDING FLT NUMBERS, RADIO SPEECH AND ACFT OPERATING IN SAME AREA ON DIFFERENT ATC FREQS (INBND 120.5, OUTBND 118.1). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR WAS F/O ON ACR X. SAYS PIC DID HAVE TELEPHONE REVIEW WITH ATC AFTER LNDG, AND LATER AFTER TAPES WERE PLAYED. CTLR HAD MEANT DSCNT CLRNC FOR COMPANY TRIP W WHO WAS WELL AHEAD OF X AND CLR OF DEP PATH OF Y. HOWEVER, CTLR USED WRONG CALL SIGN IN GIVING DSCNT CLRNC. RPTR SAYS HE THOUGHT IT UNUSUAL THAT THEY WOULD BE CLRED TO 3000' SO SOON, BUT DID NOT QUESTION CLRNC UNTIL THEY SAW ACR Y ON XING COURSE AT 5000'. RPTR DID READBACK DSCNT CLRNC, AND DID NOT HEAR COMPANY W ACKNOWLEDGE SAME CLRNC, BUT SAYS THEY MAY HAVE BLOCKED EACH OTHER IN READBACK. RPTR ACFT LEVELED OFF ABOUT 5800' TO PASS OVER Y. ACR Y HAD JUST BEEN POINTED OUT AS TFC FOR X. X AND Y WERE ON PARTYLINE, BUT CTLR NEVER DID ADVISE THAT THERE WERE SIMILAR CALL SIGNS ON FREQ.

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.