Narrative:

Flight guidance failed to capture altitude. Altitude was set and armed for 10000'. Altitude window annunciated altitude capture at 10000' MSL. Aircraft was still descending. I then pushed the altitude hold button. Aircraft immediately started to level off and climbed back to 1000' MSL. The lowest the aircraft descended during this event was 9750' MSL.

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Original NASA ASRS Text

Title: PROFILE DESCENT WITH RAPID RATE IN AUTOPLT. AUTOPLT FAILED TO LEVEL AT 10000'. OVERSHOT TO 9750'. FO PUSHED VERTICAL SPEED AND THEN ALT HOLD AT 10000'.

Narrative: FLT GUIDANCE FAILED TO CAPTURE ALT. ALT WAS SET AND ARMED FOR 10000'. ALT WINDOW ANNUNCIATED ALT CAPTURE AT 10000' MSL. ACFT WAS STILL DSNDING. I THEN PUSHED THE ALT HOLD BUTTON. ACFT IMMEDIATELY STARTED TO LEVEL OFF AND CLBED BACK TO 1000' MSL. THE LOWEST THE ACFT DSNDED DURING THIS EVENT WAS 9750' MSL.

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.