Narrative:

Air carrier X was climbed to 15000 ft. Air carrier X was given traffic at 16000FT and to expect higher passing traffic. Air carrier Y was climbed to 15000 ft on a different departure. I climbed air carrier Y to 17000 ft. Air carrier X answered; 17000 ft air carrier X. I then got on a land line to coordinate a heading for another aircraft. While I was on the land line air carrier Y asked if that climb was for him. When I hung up the line air carrier X asked if I wanted him to climb to 17000 ft. I said affirmative. I saw air carrier X's altitude at 15200 ft and asked him to verify assigned altitude at 15000 ft. Air carrier X said roger 15000 ft. Then air carrier X said I gave him a climb to 17000 ft. I said no; that was for your company air carrier Y. Separation was lost on the backside. First of all I should have caught the readback. I did have a radar assist working beside me. The radar assist missed the readback also. The radar assist should have been on the land line and not myself. When air carrier X read back the climb clearance he should have said his call sign first. I heard 17000 ft and anticipated it was air carrier Y. Air carrier Y never said his company took the clearance. I think there should be a sterile cockpit until the aircraft is at cruising altitude. Supplemental information from acn 725143: cause of problem: company having similar sounding flight numbers traveling same route and same time. This can cause someone (pilot) to receive or (ATC) to give right clearance to wrong aircraft or wrong clearance to right aircraft or to take/give someone else's clearance. Solution: have flts numbered in such a way so they are not similar flight numbers on similar rtes. This will minimize potential confusion by both pilots and ATC.

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Original NASA ASRS Text

Title: ZNY CTLR EXPERIENCED OPERROR AT 15000 FT WHEN ISSUING CONFLICTING CLRNCS WITH TWO SAME COMPANY ACFT WITH SIMILAR FLT NUMBERS.

Narrative: ACR X WAS CLBED TO 15000 FT. ACR X WAS GIVEN TFC AT 16000FT AND TO EXPECT HIGHER PASSING TFC. ACR Y WAS CLBED TO 15000 FT ON A DIFFERENT DEP. I CLBED ACR Y TO 17000 FT. ACR X ANSWERED; 17000 FT ACR X. I THEN GOT ON A LAND LINE TO COORDINATE A HDG FOR ANOTHER ACFT. WHILE I WAS ON THE LAND LINE ACR Y ASKED IF THAT CLB WAS FOR HIM. WHEN I HUNG UP THE LINE ACR X ASKED IF I WANTED HIM TO CLB TO 17000 FT. I SAID AFFIRMATIVE. I SAW ACR X'S ALT AT 15200 FT AND ASKED HIM TO VERIFY ASSIGNED ALT AT 15000 FT. ACR X SAID ROGER 15000 FT. THEN ACR X SAID I GAVE HIM A CLB TO 17000 FT. I SAID NO; THAT WAS FOR YOUR COMPANY ACR Y. SEPARATION WAS LOST ON THE BACKSIDE. FIRST OF ALL I SHOULD HAVE CAUGHT THE READBACK. I DID HAVE A RADAR ASSIST WORKING BESIDE ME. THE RADAR ASSIST MISSED THE READBACK ALSO. THE RADAR ASSIST SHOULD HAVE BEEN ON THE LAND LINE AND NOT MYSELF. WHEN ACR X READ BACK THE CLB CLRNC HE SHOULD HAVE SAID HIS CALL SIGN FIRST. I HEARD 17000 FT AND ANTICIPATED IT WAS ACR Y. ACR Y NEVER SAID HIS COMPANY TOOK THE CLRNC. I THINK THERE SHOULD BE A STERILE COCKPIT UNTIL THE ACFT IS AT CRUISING ALT. SUPPLEMENTAL INFO FROM ACN 725143: CAUSE OF PROB: COMPANY HAVING SIMILAR SOUNDING FLT NUMBERS TRAVELING SAME RTE AND SAME TIME. THIS CAN CAUSE SOMEONE (PLT) TO RECEIVE OR (ATC) TO GIVE RIGHT CLRNC TO WRONG ACFT OR WRONG CLRNC TO RIGHT ACFT OR TO TAKE/GIVE SOMEONE ELSE'S CLRNC. SOLUTION: HAVE FLTS NUMBERED IN SUCH A WAY SO THEY ARE NOT SIMILAR FLT NUMBERS ON SIMILAR RTES. THIS WILL MINIMIZE POTENTIAL CONFUSION BY BOTH PLTS AND ATC.

Data retrieved from NASA's ASRS site as of January 2009 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.