Narrative:

Location: runways 9 and 12 mia airport. Taxied out for takeoff at mia given runway 9L. At taxiway Z change from taxiway north to taxiway M to await closeout. After receiving closeout taxied to hold short line runway 9L with B757 on left holding for runway 12. B757 took off runway 9L and we were given taxi into position runway 12. I did not hear runway 12 and went straight ahead toward runway 9L. I saw an aircraft on final runway 9L and at about the same time the first officer looked up after entering runway 12 into FMC and told me that we were given runway 12. We stopped short of the runway but beyond the hold short line and called the tower. The tower had already changed the runway 9L aircraft to runway 12. They then cleared us onto runway 9L and then for takeoff. For some reason I never even thought runway 12 would be our runway and was not listening hard enough to clearance but my other checks caught my mistake. Prior to taking position and awareness of first officer and folks in tower prevented any further problems.

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Original NASA ASRS Text

Title: TWO RWYS IN USE FOR TKOF AT MIA. RPTR CAPT WAS EXPECTING RWY 9L, PARTLY BECAUSE THE PRECEDING ACFT HAD TAKEN OFF FROM THAT RWY. HIS CLRNC WAS FOR RWY 12, AND WHEN HE WAS CLRED INTO POS, HE HEADED FOR RWY 9L AT WHICH TIME HIS FO TOLD HIM THEIRS WAS RWY 12. BY THEN HE HAD ALREADY CROSSED THE HOLD LINE AND THE TWR HAD AN ACFT ON FINAL CHANGE LNDG RWY.

Narrative: LOCATION: RWYS 9 AND 12 MIA ARPT. TAXIED OUT FOR TKOF AT MIA GIVEN RWY 9L. AT TXWY Z CHANGE FROM TXWY N TO TXWY M TO AWAIT CLOSEOUT. AFTER RECEIVING CLOSEOUT TAXIED TO HOLD SHORT LINE RWY 9L WITH B757 ON L HOLDING FOR RWY 12. B757 TOOK OFF RWY 9L AND WE WERE GIVEN TAXI INTO POS RWY 12. I DID NOT HEAR RWY 12 AND WENT STRAIGHT AHEAD TOWARD RWY 9L. I SAW AN ACFT ON FINAL RWY 9L AND AT ABOUT THE SAME TIME THE FO LOOKED UP AFTER ENTERING RWY 12 INTO FMC AND TOLD ME THAT WE WERE GIVEN RWY 12. WE STOPPED SHORT OF THE RWY BUT BEYOND THE HOLD SHORT LINE AND CALLED THE TWR. THE TWR HAD ALREADY CHANGED THE RWY 9L ACFT TO RWY 12. THEY THEN CLRED US ONTO RWY 9L AND THEN FOR TKOF. FOR SOME REASON I NEVER EVEN THOUGHT RWY 12 WOULD BE OUR RWY AND WAS NOT LISTENING HARD ENOUGH TO CLRNC BUT MY OTHER CHKS CAUGHT MY MISTAKE. PRIOR TO TAKING POS AND AWARENESS OF FO AND FOLKS IN TWR PREVENTED ANY FURTHER PROBS.

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.