Narrative:

We were filed for mth out of miami. New first officer to the area and I the PF was taxiing. During the taxi we were cleared to 9L. When ever we taxied to an east runway and were filed for an airport to the south, we would get a runway change to 12 99 percent of the time. This was that 1 percent that we were cleared for departure on 9L. I thought we were cleared to depart 12 so I took runway 12. I always check for final traffic prior to entering a runway, and there was none. The controller told us he assigned 9L. I immediately cleared 12 and the controller said it was alright if we wanted 12. We were then cleared to depart 12. There was no traffic around, and we were not in the middle of a push. This hopefully will be the last time I ever do such an ignorant complacent thing. Contributing factors are complacency, new first officer to the airport, break down in communication between crew. Callback conversation with reporter revealed the following information. Reporter states no blame anywhere but on his shoulders. His complacency in expecting the routine of runway assignment was problem. First officer very new and concern for slowing down to assure all tasks completed without feeling rushed was distracting. Never again. New procedure he has adopted to confirm runway assignment prior to taxi onto runway.

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Original NASA ASRS Text

Title: COMMUTER ACFT ENTERS WRONG RWY FOR TKOF. CLRS RWY THEN CTLR SAYS OK TKOF THAT RWY.

Narrative: WE WERE FILED FOR MTH OUT OF MIAMI. NEW FO TO THE AREA AND I THE PF WAS TAXIING. DURING THE TAXI WE WERE CLRED TO 9L. WHEN EVER WE TAXIED TO AN E RWY AND WERE FILED FOR AN ARPT TO THE S, WE WOULD GET A RWY CHANGE TO 12 99 PERCENT OF THE TIME. THIS WAS THAT 1 PERCENT THAT WE WERE CLRED FOR DEP ON 9L. I THOUGHT WE WERE CLRED TO DEPART 12 SO I TOOK RWY 12. I ALWAYS CHK FOR FINAL TFC PRIOR TO ENTERING A RWY, AND THERE WAS NONE. THE CTLR TOLD US HE ASSIGNED 9L. I IMMEDIATELY CLRED 12 AND THE CTLR SAID IT WAS ALRIGHT IF WE WANTED 12. WE WERE THEN CLRED TO DEPART 12. THERE WAS NO TFC AROUND, AND WE WERE NOT IN THE MIDDLE OF A PUSH. THIS HOPEFULLY WILL BE THE LAST TIME I EVER DO SUCH AN IGNORANT COMPLACENT THING. CONTRIBUTING FACTORS ARE COMPLACENCY, NEW FO TO THE ARPT, BREAK DOWN IN COM BTWN CREW. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR STATES NO BLAME ANYWHERE BUT ON HIS SHOULDERS. HIS COMPLACENCY IN EXPECTING THE ROUTINE OF RWY ASSIGNMENT WAS PROBLEM. FO VERY NEW AND CONCERN FOR SLOWING DOWN TO ASSURE ALL TASKS COMPLETED WITHOUT FEELING RUSHED WAS DISTRACTING. NEVER AGAIN. NEW PROC HE HAS ADOPTED TO CONFIRM RWY ASSIGNMENT PRIOR TO TAXI ONTO RWY.

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.