Narrative:

During preflight preparations, the IRS's were aligned by the captain while the first officer was absent from the cockpit. Upon returning to the cockpit, the first officer turned off the IRS's in preparation for alignment. Not realizing that they had already been done. The captain was absent from the cockpit at the time. The appropriate checklists were accomplished prior to pushback and start. However, neither crew member reset the navigation on the IRS. The warn flags in the flight instruments appeared to be normal as in the adjustment period and didn't appear out of the ordinary. Since the IRS's had already aligned, no abnormal indications were noted in the FMC or the IRS panel. The before takeoff checklist was done shortly after taxi began to the active runway. While flight instruments are not specifically incorporated into these checks, the warning flags and erroneous heading indication should have been obvious. Takeoff clearance was received and on rotation the invalid instruments indicating were detected. Fortunately the WX was good VFR and the initial climb out was accomplished by the standby attitude indicator for reference. During the climb a level off at 6800 ft was requested to remain VFR, to reset the heading in the FMC. It took about 3-5 min to bring everything back to normal and continue a normal departure and arrival at our destination. Suggestion -- be more vigilant on heading check on taxi out. Also our FMC's could not be used at the time because of an inoperative fuel gauge, this also added to the situation because the FMC's would normally flash a note that it had no position information.

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Original NASA ASRS Text

Title: TKOF WITH IRS IN ALIGN.

Narrative: DURING PREFLT PREPARATIONS, THE IRS'S WERE ALIGNED BY THE CAPT WHILE THE FO WAS ABSENT FROM THE COCKPIT. UPON RETURNING TO THE COCKPIT, THE FO TURNED OFF THE IRS'S IN PREPARATION FOR ALIGNMENT. NOT REALIZING THAT THEY HAD ALREADY BEEN DONE. THE CAPT WAS ABSENT FROM THE COCKPIT AT THE TIME. THE APPROPRIATE CHKLISTS WERE ACCOMPLISHED PRIOR TO PUSHBACK AND START. HOWEVER, NEITHER CREW MEMBER RESET THE NAV ON THE IRS. THE WARN FLAGS IN THE FLT INSTS APPEARED TO BE NORMAL AS IN THE ADJUSTMENT PERIOD AND DIDN'T APPEAR OUT OF THE ORDINARY. SINCE THE IRS'S HAD ALREADY ALIGNED, NO ABNORMAL INDICATIONS WERE NOTED IN THE FMC OR THE IRS PANEL. THE BEFORE TKOF CHKLIST WAS DONE SHORTLY AFTER TAXI BEGAN TO THE ACTIVE RWY. WHILE FLT INSTS ARE NOT SPECIFICALLY INCORPORATED INTO THESE CHKS, THE WARNING FLAGS AND ERRONEOUS HDG INDICATION SHOULD HAVE BEEN OBVIOUS. TKOF CLRNC WAS RECEIVED AND ON ROTATION THE INVALID INSTS INDICATING WERE DETECTED. FORTUNATELY THE WX WAS GOOD VFR AND THE INITIAL CLBOUT WAS ACCOMPLISHED BY THE STANDBY ATTITUDE INDICATOR FOR REF. DURING THE CLB A LEVEL OFF AT 6800 FT WAS REQUESTED TO REMAIN VFR, TO RESET THE HDG IN THE FMC. IT TOOK ABOUT 3-5 MIN TO BRING EVERYTHING BACK TO NORMAL AND CONTINUE A NORMAL DEP AND ARR AT OUR DEST. SUGGESTION -- BE MORE VIGILANT ON HDG CHK ON TAXI OUT. ALSO OUR FMC'S COULD NOT BE USED AT THE TIME BECAUSE OF AN INOP FUEL GAUGE, THIS ALSO ADDED TO THE SIT BECAUSE THE FMC'S WOULD NORMALLY FLASH A NOTE THAT IT HAD NO POS INFO.

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.