Narrative:

Taxi instructions were given at point 'a' to 'taxi to runway 12R via txwys Y and east, hold short of runway 12L.' I started to taxi the assigned route till point 'B.' an amended clearance was given: 'taxi to runway 12R via taxiway H and hold short of runway 12L.' I taxied via the new route and stopped at point 'C.' next transmission: 'cross runway 12L, turn right onto taxiway M, hold short of runway 12R, expect to depart runway 12R at intersection D. Monitor tower.' after a short delay, tower contacted me (this is where confusion starts). I heard 'taxi into position and hold runway 12R.' the controller may have said or meant runway 12L. I started a left turn and tower immediately said, 'that was supposed to be a right turn, hold your position there.' I was in the runway area of runway 17 at that time but not off runway 12R. I stayed in this position while 2 aircraft departed in front of me on runway 12R. I was then told 'cleared for takeoff runway 12R, turn left heading 340 degrees.' I was told to contact departure and the rest of the flight was uneventful. I may have had runway 12R in my head so that I didn't notice when they actually said runway 12L. On the other hand, they may have said runway 12R and meant runway 12L. If the runway change was made, it was not emphasized. The mistake also could have been made in xfer from ground to tower. It is still unclr to me whether the mistake was made by me or ATC. Nonetheless, no danger was created and no slowdowns occurred. Runway 17 was not in use at the time.

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Original NASA ASRS Text

Title: PA31T PLT RPT ON CONFUSION REGARDING A TAXI CLRNC AND TKOF RWY ASSIGNMENT BY ATC AT HOU, TX.

Narrative: TAXI INSTRUCTIONS WERE GIVEN AT POINT 'A' TO 'TAXI TO RWY 12R VIA TXWYS Y AND E, HOLD SHORT OF RWY 12L.' I STARTED TO TAXI THE ASSIGNED RTE TILL POINT 'B.' AN AMENDED CLRNC WAS GIVEN: 'TAXI TO RWY 12R VIA TXWY H AND HOLD SHORT OF RWY 12L.' I TAXIED VIA THE NEW RTE AND STOPPED AT POINT 'C.' NEXT XMISSION: 'CROSS RWY 12L, TURN R ONTO TXWY M, HOLD SHORT OF RWY 12R, EXPECT TO DEPART RWY 12R AT INTXN D. MONITOR TWR.' AFTER A SHORT DELAY, TWR CONTACTED ME (THIS IS WHERE CONFUSION STARTS). I HEARD 'TAXI INTO POS AND HOLD RWY 12R.' THE CTLR MAY HAVE SAID OR MEANT RWY 12L. I STARTED A L TURN AND TWR IMMEDIATELY SAID, 'THAT WAS SUPPOSED TO BE A R TURN, HOLD YOUR POS THERE.' I WAS IN THE RWY AREA OF RWY 17 AT THAT TIME BUT NOT OFF RWY 12R. I STAYED IN THIS POS WHILE 2 ACFT DEPARTED IN FRONT OF ME ON RWY 12R. I WAS THEN TOLD 'CLRED FOR TKOF RWY 12R, TURN L HEADING 340 DEGS.' I WAS TOLD TO CONTACT DEP AND THE REST OF THE FLT WAS UNEVENTFUL. I MAY HAVE HAD RWY 12R IN MY HEAD SO THAT I DIDN'T NOTICE WHEN THEY ACTUALLY SAID RWY 12L. ON THE OTHER HAND, THEY MAY HAVE SAID RWY 12R AND MEANT RWY 12L. IF THE RWY CHANGE WAS MADE, IT WAS NOT EMPHASIZED. THE MISTAKE ALSO COULD HAVE BEEN MADE IN XFER FROM GND TO TWR. IT IS STILL UNCLR TO ME WHETHER THE MISTAKE WAS MADE BY ME OR ATC. NONETHELESS, NO DANGER WAS CREATED AND NO SLOWDOWNS OCCURRED. RWY 17 WAS NOT IN USE AT THE TIME.

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.