Narrative:

Cruising at 33000 ft; the stabilizer out of trim light came on. We ran the stabilizer out of trim checklist in the QRH; and determined that the autoplt was not trimming the stabilizer properly. We notified ATC; left rvsm airspace. We then notified dispatch. We continued on with the autoplt disengaged.supplemental information from acn 722005: we were in cruise flight at FL330; when the stabilizer out of trim light illuminated and the aircraft slowly began to climb. We noticed the malfunction immediately; and took over hand flying the aircraft. We completed the QRH procedure and determined that the autoplt was not trimming properly. We notified ATC of the equipment failure; and that we needed to leave rvsm airspace.callback conversation with reporter acn 722002 revealed the following information: reporter stated that because the autoplt was required to be disconnected as a result of that aircraft's particular autoplt trim failure; the aircraft could no longer maintain altitude. At this point the rvsm requirement was no longer met. The reporter also stated that once the aircraft was at a lower altitude and being hand flown; the crew became fatigued by the requirement to manually maintain altitude and they 'had their hands full.'

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Original NASA ASRS Text

Title: A B737-300 DSNDED OUT OF RVSM AIRSPACE FOLLOWING AN AUTOPLT TRIM MALFUNCTION BECAUSE IT NO LONGER MET THE RVSM AIRSPACE REQUIREMENTS.

Narrative: CRUISING AT 33000 FT; THE STAB OUT OF TRIM LIGHT CAME ON. WE RAN THE STAB OUT OF TRIM CHECKLIST IN THE QRH; AND DETERMINED THAT THE AUTOPLT WAS NOT TRIMMING THE STABILIZER PROPERLY. WE NOTIFIED ATC; LEFT RVSM AIRSPACE. WE THEN NOTIFIED DISPATCH. WE CONTINUED ON WITH THE AUTOPLT DISENGAGED.SUPPLEMENTAL INFO FROM ACN 722005: WE WERE IN CRUISE FLT AT FL330; WHEN THE STAB OUT OF TRIM LIGHT ILLUMINATED AND THE ACFT SLOWLY BEGAN TO CLB. WE NOTICED THE MALFUNCTION IMMEDIATELY; AND TOOK OVER HAND FLYING THE ACFT. WE COMPLETED THE QRH PROC AND DETERMINED THAT THE AUTOPLT WAS NOT TRIMMING PROPERLY. WE NOTIFIED ATC OF THE EQUIPMENT FAILURE; AND THAT WE NEEDED TO LEAVE RVSM AIRSPACE.CALLBACK CONVERSATION WITH RPTR ACN 722002 REVEALED THE FOLLOWING INFO: RPTR STATED THAT BECAUSE THE AUTOPLT WAS REQUIRED TO BE DISCONNECTED AS A RESULT OF THAT ACFT'S PARTICULAR AUTOPLT TRIM FAILURE; THE ACFT COULD NO LONGER MAINTAIN ALT. AT THIS POINT THE RVSM REQUIREMENT WAS NO LONGER MET. THE RPTR ALSO STATED THAT ONCE THE ACFT WAS AT A LOWER ALT AND BEING HAND FLOWN; THE CREW BECAME FATIGUED BY THE REQUIREMENT TO MANUALLY MAINTAIN ALT AND THEY 'HAD THEIR HANDS FULL.'

Data retrieved from NASA's ASRS site as of January 2009 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.