Narrative:

Air carrier X was level at FL310 requesting FL390. Air carrier Y was conflicting traffic at FL330. Air carrier Z called on frequency climbing to FL290. I issued climb to air carrier X to FL330. I heard the readback from a garbled company but clear number of Z. I then issued TA's to air carrier X with no response. My d-side then alerted me that air carrier X was climbing. I called air carrier X to verify at FL310, no response. I called again to air carrier X. He finally responded to climbing to FL330. On review of the tape I gave a clearance to air carrier X instead of air carrier Z. I heard garbled company (not clear if X or Z) but clear numbers. Since we have no company Z, I assumed it was air carrier Z. Supplemental information from acn 267181:I was coordinating with ZKC fam sector on a pointout at FL240. After coming offline I noticed air carrier X who was level at FL310 and waiting to climb, show FL311 on mode C and then FL312. I told the radar controller about mode C and he questioned air carrier X (it took 2 calls) to verify level at FL310 and he said no, he was climbing to FL330. Air carrier X lost separation with air carrier Y. After review of tape it appears radar controller issued a climb to an air carrier X meant for an air carrier Z to FL330. The tape was garbled on the air carrier identify but the Z was clear and acknowledged the climb to FL330.

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Original NASA ASRS Text

Title: SIMILAR NUMBERS ACR X UNAUTH CLB TO OCCUPIED ALT HAD LTSS FROM ACR Y. PLTDEV.

Narrative: ACR X WAS LEVEL AT FL310 REQUESTING FL390. ACR Y WAS CONFLICTING TFC AT FL330. ACR Z CALLED ON FREQ CLBING TO FL290. I ISSUED CLB TO ACR X TO FL330. I HEARD THE READBACK FROM A GARBLED COMPANY BUT CLR NUMBER OF Z. I THEN ISSUED TA'S TO ACR X WITH NO RESPONSE. MY D-SIDE THEN ALERTED ME THAT ACR X WAS CLBING. I CALLED ACR X TO VERIFY AT FL310, NO RESPONSE. I CALLED AGAIN TO ACR X. HE FINALLY RESPONDED TO CLBING TO FL330. ON REVIEW OF THE TAPE I GAVE A CLRNC TO ACR X INSTEAD OF ACR Z. I HEARD GARBLED COMPANY (NOT CLR IF X OR Z) BUT CLR NUMBERS. SINCE WE HAVE NO COMPANY Z, I ASSUMED IT WAS ACR Z. SUPPLEMENTAL INFORMATION FROM ACN 267181:I WAS COORDINATING WITH ZKC FAM SECTOR ON A POINTOUT AT FL240. AFTER COMING OFFLINE I NOTICED ACR X WHO WAS LEVEL AT FL310 AND WAITING TO CLB, SHOW FL311 ON MODE C AND THEN FL312. I TOLD THE RADAR CTLR ABOUT MODE C AND HE QUESTIONED ACR X (IT TOOK 2 CALLS) TO VERIFY LEVEL AT FL310 AND HE SAID NO, HE WAS CLBING TO FL330. ACR X LOST SEPARATION WITH ACR Y. AFTER REVIEW OF TAPE IT APPEARS RADAR CTLR ISSUED A CLB TO AN ACR X MEANT FOR AN ACR Z TO FL330. THE TAPE WAS GARBLED ON THE ACR IDENT BUT THE Z WAS CLR AND ACKNOWLEDGED THE CLB TO FL330.

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.