Narrative:

During taxi for takeoff, we heard tower issue windshear advisories. The captain directed a maximum power takeoff and I suggested using 'flaps 5 degrees' to conform with the flight manual. He agreed and I plugged ACARS for the new takeoff data. The before takeoff checklist had already been completed. As we approached the hold short (approximately 50 yards away) I told tower that we were ready to go. I heard tower clear someone for takeoff. I missed the call sign and did not respond. The captain did not respond either but he began to cross the hold short line. I asked tower to confirm if we were cleared for takeoff. We were then told to hold short by tower. When we stopped we were about 10-15 ft across the line, but not nearly on the runway. I told tower our position and he said 'that's ok, just hold short.' our situation did not improve. I missed resetting the flaps in the confusion, but the captain caught it. Tower cleared us for takeoff. I believed I heard 'fly runway heading.' once airborne, the captain began a left turn. He had reset his heading bug to the takeoff clearance he had mistakenly followed before. I confirmed our departure instructions with him immediately. At this point we realized that we were in an error chain. We made every effort to tighten and improve our situational awareness and we proceeded without further incident. We were correct to reconfigure the aircraft for takeoff in a windshear environment. We were incorrect in rushing. We should have stopped the aircraft and rerun the before takeoff checklist. We were saved from any incident by good enough situational awareness to note that questions needed to asked (were we cleared? Are the flaps correctly set? What was our assigned heading?). Further, we employed solid air crew coordination/command leadership resource management techniques to recognize and break an error chain.

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Original NASA ASRS Text

Title: RWY INCURSION AND TRACK DEV WHEN CREW CONCEPT BREAKS DOWN.

Narrative: DURING TAXI FOR TKOF, WE HEARD TWR ISSUE WINDSHEAR ADVISORIES. THE CAPT DIRECTED A MAX PWR TKOF AND I SUGGESTED USING 'FLAPS 5 DEGS' TO CONFORM WITH THE FLT MANUAL. HE AGREED AND I PLUGGED ACARS FOR THE NEW TKOF DATA. THE BEFORE TKOF CHKLIST HAD ALREADY BEEN COMPLETED. AS WE APCHED THE HOLD SHORT (APPROX 50 YARDS AWAY) I TOLD TWR THAT WE WERE READY TO GO. I HEARD TWR CLR SOMEONE FOR TKOF. I MISSED THE CALL SIGN AND DID NOT RESPOND. THE CAPT DID NOT RESPOND EITHER BUT HE BEGAN TO CROSS THE HOLD SHORT LINE. I ASKED TWR TO CONFIRM IF WE WERE CLRED FOR TKOF. WE WERE THEN TOLD TO HOLD SHORT BY TWR. WHEN WE STOPPED WE WERE ABOUT 10-15 FT ACROSS THE LINE, BUT NOT NEARLY ON THE RWY. I TOLD TWR OUR POS AND HE SAID 'THAT'S OK, JUST HOLD SHORT.' OUR SIT DID NOT IMPROVE. I MISSED RESETTING THE FLAPS IN THE CONFUSION, BUT THE CAPT CAUGHT IT. TWR CLRED US FOR TKOF. I BELIEVED I HEARD 'FLY RWY HDG.' ONCE AIRBORNE, THE CAPT BEGAN A L TURN. HE HAD RESET HIS HDG BUG TO THE TKOF CLRNC HE HAD MISTAKENLY FOLLOWED BEFORE. I CONFIRMED OUR DEP INSTRUCTIONS WITH HIM IMMEDIATELY. AT THIS POINT WE REALIZED THAT WE WERE IN AN ERROR CHAIN. WE MADE EVERY EFFORT TO TIGHTEN AND IMPROVE OUR SITUATIONAL AWARENESS AND WE PROCEEDED WITHOUT FURTHER INCIDENT. WE WERE CORRECT TO RECONFIGURE THE ACFT FOR TKOF IN A WINDSHEAR ENVIRONMENT. WE WERE INCORRECT IN RUSHING. WE SHOULD HAVE STOPPED THE ACFT AND RERUN THE BEFORE TKOF CHKLIST. WE WERE SAVED FROM ANY INCIDENT BY GOOD ENOUGH SITUATIONAL AWARENESS TO NOTE THAT QUESTIONS NEEDED TO ASKED (WERE WE CLRED? ARE THE FLAPS CORRECTLY SET? WHAT WAS OUR ASSIGNED HDG?). FURTHER, WE EMPLOYED SOLID AIR CREW COORD/COMMAND LEADERSHIP RESOURCE MGMNT TECHNIQUES TO RECOGNIZE AND BREAK AN ERROR CHAIN.

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.