SIMILAR CALL SIGNS; ACCEPTANCE OF THE WRONG CLRNC AND A MISSED READBACK COUPLED WITH CHKLIST ACTIVITY DISTRS LEAD TO A TAKEOFF WITHOUT CLRNC AND A RWY INCURSION BY A TAXIING ACFT WHEN THE RWY CROSSING CLRNC IS TOO LATE FOR A STOP SHORT OF THE HOLD SHORT LINE.

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I WAS DOING A SCHEDULED FLT FROM DFW TO XNA. WE WERE CLRED INTO POS FOR RWY 36R AT DFW. AS WE PROCEEDED ONTO THE RWY; THE CAPT CALLED FOR THE 'BEFORE TKOF' CHKLIST. THIS CHKLIST IS PARTIALLY A CHALLENGE AND RESPONSE CHKLIST. THE REST OF THE LIST IS DONE VERBALLY BY THE FO. AS WE RAN THROUGH THE CHKLIST; I HEARD 'ACFT X CLRED FOR TKOF.' I RESPONDED; 'CLRED FOR TKOF; RWY 36R; ACFT X.' AS WE TURNED THE ACFT ONTO THE CTRLINE; I ASKED THE CAPT IF HE WANTED THE EXTERIOR LIGHTS ON. HE SAID YES. THIS LAST ITEM ON THE CHKLIST IS DONE WHEN WE HAVE BEEN CLRED FOR TKOF. I BELIEVE THAT DUE TO THE VERBAL NATURE OF THE CHKLIST; THIS IS WHERE THE MISUNDERSTANDING AROSE. (I WILL EXPLAIN THIS LATER IN THIS BRIEF). AS WE ROLLED DOWN THE RWY; I HEARD DFW TWR TELL ACFT Y TO STOP WHERE THEY WERE. I THOUGHT THAT ACFT Y HAD MISUNDERSTOOD A TAXI CLRNC. BY THE TIME WE WERE ABEAM THEM; WE WERE WELL ABOVE THEM. AS WE PASSED OVER ACFT Y; I NOTICED THAT THEY WERE A FEW FT PAST THE HOLD SHORT LINE ON A TXWY THAT INTERSECTED RWY 36R. AS WE FLEW TO XNA; CTR ASKED US TO CALL DFW TWR WHEN WE ARRIVED AT XNA. UPON ARR AT XNA; MY CAPT CALLED DFW TWR AND SPOKE WITH A SUPVR. THE SUPVR EXPLAINED THAT ANOTHER ACFT (ACFT Z) HAD BEEN CLRED FOR TKOF FROM RWY 31L AND NOT US. I THINK WHAT HAPPENED WAS; WHILE WE WERE VERBALLY DOING THE TKOF CHKLIST; I MUST HAVE COMBINED THE NUMBERS FROM ACFT AND RWY AND HEARD 'ACFT X.' I DIDN'T REALIZE THAT AT XC00 IN THE AFTERNOON DFW TWR WAS WORKING RWY 36R; RWY 36L; AND RWY 31L. SINCE THERE WAS NO OTHER ACFT ON THE RWY (RWY 36R) AND I DIDN'T KNOW TWR WAS WORKING 3 RWYS; I HAD NO REASON TO THINK IT COULDN'T BE US THEY WERE TELLING 'CLRED FOR TKOF.' AFTER REVIEWING THE TAPES; THE SUPVR TOLD THE CAPT THAT DFW TWR WOULD TAKE RESPONSIBILITY FOR WHAT HAPPENED. THE SUPVR SAID THAT SHE COULD HEAR MY TKOF CLRNC READBACK. SHE SAID THE TWR CTLR SHOULD HAVE ASKED FOR CLARIFICATION AS TO WHO WAS TAKING OFF FROM WHAT RWY AND/OR COULD HAVE ASKED US TO ABORT THE ROLL WHEN HE SAW US MOVING DOWN RWY 36R. IN CLOSING; I AM NOT THE TYPE OF PLT THAT TAKES OFF WITHOUT A CLRNC. THERE HAVE BEEN OCCASIONS WHEN I HAVE BEEN UNSURE SO I ASKED THE TWR FOR CLARIFICATION. IN THIS INSTANCE; I BELIEVE THAT DUE TO THE VERBAL NATURE OF THE CHKLIST; I MISHEARD THE INSTRUCTION; BUT WAS SURE IT WAS FOR US AND CONTINUED THE TKOF. SUPPLEMENTAL INFO FROM ACN 513795: ABCD DEPARTING DFW TO XNA AT XC00 WAS HOLDING SHORT OF ACTIVE RWY 36R DFW. A HEAVY ACFT JUST DEPARTED; WHEN WE WERE INFORMED TO TAKE POS AND HOLD RWY 36R. AS I SLOWLY TOOK POS MAKING AN 90 DEG ENTRY; I REQUESTED BEFORE TAKEOFF CHKLIST. THE CO-PLT READ ALOUD THE ITEMS. DFW TWR SPOKE EXACTLY; THE SAME TIME; ITEMS WERE READ. I DID NOT HEAR WHAT TWR SAID; OUR VOICES OVER-RODE TWRS. I DID NOT THINK IT WAS FOR US; SINCE WAKE TURB SEPARATION JUST STARTED; BUT THE CO-PLT HEARD ACR X FLT ABCD CLRED FOR TAKEOFF (RWY 36R?). THE ONLY PART I HEARD FROM TWR WAS ENDING TRANSMISSION WAS CLRED FOR TAKEOFF. THE CO-PLT CLEARLY READ BACK; CLRED FOR TAKEOFF ON RWY 36R; ACR X FLT ABCD. DFW TWR DID NOT CORRECT THE READBACK. WHILE STILL COMPLETING THE 90 DEG TURN ON THE ACTIVE RWY; CO-PLT ASKED IF I WANTED HIM TO TURN ON EXTERIOR LIGHTS; WITH HANDS FULL; I REPLIED YES; TURN ALL THE LIGHTS ON. THE POINT HERE IS; THIS IS WHERE DFW TWR WAS TALKING TO AN ACR Y ACFT AND WE DIDNT CATCH THE CONVERSATION; BECAUSE WE WERE STILL VERBALLY COMPLETING THE CHKLIST. A NORMAL TKOF WAS MADE; WHEN WE BOTH HEARD DFW TWR SAY ACR Y STOP; BUT WE NOTED ACR Y ACFT HAD ALREADY STOPPED. I THOUGHT ACR Y MIGHT HAVE MISSED A TRANSMISSION. WE WERE WELL ABOVE ACR Y ACFT; WHEN WE FLEW PAST ABEAM. WE THOUGHT NOTHING OF IT TILL HALF WAY TO XNA; WHEN CTR TOLD US TO CALL DFW TWR. I CALLED AT XNA ARPT. DFW TWR MANAGER ON DUTY SAID WE DEPARTED WITHOUT A CLRNC. MANAGER ON DUTY SAID IT WAS FOR ACR X EFGH FOR RWY 31L. I COULDNT BELIEVE IT AND I SAID; WE READ BACK WE WERE DEPARTING RWY 36R FOR ACR X FLT ABCD. MANAGER ON DUTY SAID I KNOW; WE HEARD THE TAPES. I SAIDSO; NOW WHAT? MANAGER ON DUTY SAID ITS OUR FAULT; BECAUSE YOU GAVE A FULL READBACK AND DFW TWR SHOULD HAVE CAUGHT THE MISTAKE AND CORRECTED IT. MANAGER ON DUTY ASKED ME A FEW MORE QUESTIONS ABOUT OTHER ACFT ON FREQ. I SAID I WAS BUSY WITH CHECKLIST AND COMPLETING MY REQUIRED DUTIES. THE REST IS HISTORY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CROSSING ACR WHOSE CLRNC TO CROSS WAS CANCELED WAS AN MD80. HE WAS UNABLE TO STOP UNTIL SLIGHTLY ACROSS THE HOLD SHORT LINE; BUT WAS WELL OFF THE RWY. THE ACFT X WAS APPROX 1400 FT AGL AS IT WENT BY THE INTERSECTION THAT WAS APPROX 9000 FT DOWN THE RWY.