Narrative:

After pushback, we were cleared to taxi to runway 12R at hou airport. The airport was in the midst of changing active runways and as a result, several runways were being used. We were instructed to 'hold short of runway 12R' and we switched over to tower. Tower was very busy as he had 2 opposite direction departures (runway 30L) waiting for departure, another aircraft waiting for takeoff at runway 22 and us (air carrier X), holding short of runway 12R. In addition, he was handling an FAA flight check aircraft flying an approach to runway 12R (ILS). Both the captain and I heard our clearance 'air carrier X cleared for takeoff, turn left heading 150 degrees.' I began the readback but was confused as to the turn. (A 150 degree heading from runway 12R is a right turn.) I fumbled and then read back 'heading 150 degrees, cleared for takeoff, air carrier X.' on rollout, I remembered hearing tower urge an aircraft on runway 22 to begin his roll. That aircraft indicated with some confusion that they had not accepted a takeoff clearance and that they would need additional time on climb out. We then were told by tower 'air carrier X cleared for takeoff, turn left heading 350 degrees.' we queried tower and again received the same clearance. We held our heading of 150 degrees and explained again. Tower told us to turn left to a 350 degree heading and handed us to departure. I believe we were confused with the aircraft at runway 22 because of our call sign. I also believe that several distrs at the time caused the controller and us to fail to catch the mistake.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737 FLC INADVERTENTLY TOOK OFF PRIOR TO TKOF CLRNC DUE TO MISTAKING THE RWY NUMBER WITH THEIR CALL SIGN NUMBER, WHICH WAS THE SAME.

Narrative: AFTER PUSHBACK, WE WERE CLRED TO TAXI TO RWY 12R AT HOU ARPT. THE ARPT WAS IN THE MIDST OF CHANGING ACTIVE RWYS AND AS A RESULT, SEVERAL RWYS WERE BEING USED. WE WERE INSTRUCTED TO 'HOLD SHORT OF RWY 12R' AND WE SWITCHED OVER TO TWR. TWR WAS VERY BUSY AS HE HAD 2 OPPOSITE DIRECTION DEPS (RWY 30L) WAITING FOR DEP, ANOTHER ACFT WAITING FOR TKOF AT RWY 22 AND US (ACR X), HOLDING SHORT OF RWY 12R. IN ADDITION, HE WAS HANDLING AN FAA FLT CHK ACFT FLYING AN APCH TO RWY 12R (ILS). BOTH THE CAPT AND I HEARD OUR CLRNC 'ACR X CLRED FOR TKOF, TURN L HDG 150 DEGS.' I BEGAN THE READBACK BUT WAS CONFUSED AS TO THE TURN. (A 150 DEG HDG FROM RWY 12R IS A R TURN.) I FUMBLED AND THEN READ BACK 'HDG 150 DEGS, CLRED FOR TKOF, ACR X.' ON ROLLOUT, I REMEMBERED HEARING TWR URGE AN ACFT ON RWY 22 TO BEGIN HIS ROLL. THAT ACFT INDICATED WITH SOME CONFUSION THAT THEY HAD NOT ACCEPTED A TKOF CLRNC AND THAT THEY WOULD NEED ADDITIONAL TIME ON CLBOUT. WE THEN WERE TOLD BY TWR 'ACR X CLRED FOR TKOF, TURN L HDG 350 DEGS.' WE QUERIED TWR AND AGAIN RECEIVED THE SAME CLRNC. WE HELD OUR HDG OF 150 DEGS AND EXPLAINED AGAIN. TWR TOLD US TO TURN L TO A 350 DEG HDG AND HANDED US TO DEP. I BELIEVE WE WERE CONFUSED WITH THE ACFT AT RWY 22 BECAUSE OF OUR CALL SIGN. I ALSO BELIEVE THAT SEVERAL DISTRS AT THE TIME CAUSED THE CTLR AND US TO FAIL TO CATCH THE MISTAKE.

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.