Narrative:

Flight xyz out on time, normal checklists were being used. At the end of the runway, first officer made PA announcement, 'flight attendants prepare cabin for takeoff.' after the PA, cleared for takeoff. Upon reaching sterile cockpit altitude (10000 ft) the flight crew came in and told that somebody was in the bathroom during takeoff. Possible breakdown was that a flight attendant did not make a return call for 'ready for takeoff' and that we went ahead and took off anyway. Another possible breakdown is that the flight attendant did not notify the captain upon removing a passenger during taxi.

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Original NASA ASRS Text

Title: AN MDT COMMERCIAL FIXED WING ACFT MADE A TKOF AND CLBED TO 10000 FT WITH A PAX IN THE LAVATORY.

Narrative: FLT XYZ OUT ON TIME, NORMAL CHKLISTS WERE BEING USED. AT THE END OF THE RWY, FO MADE PA ANNOUNCEMENT, 'FLT ATTENDANTS PREPARE CABIN FOR TKOF.' AFTER THE PA, CLRED FOR TKOF. UPON REACHING STERILE COCKPIT ALT (10000 FT) THE FLC CAME IN AND TOLD THAT SOMEBODY WAS IN THE BATHROOM DURING TKOF. POSSIBLE BREAKDOWN WAS THAT A FLT ATTENDANT DID NOT MAKE A RETURN CALL FOR 'READY FOR TKOF' AND THAT WE WENT AHEAD AND TOOK OFF ANYWAY. ANOTHER POSSIBLE BREAKDOWN IS THAT THE FLT ATTENDANT DID NOT NOTIFY THE CAPT UPON REMOVING A PAX DURING TAXI.

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.