Widebody transport climbs above assigned altitude due to failure of autoplt to capture.

Attributes
ACN	318540
Time
Date	199509
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : tth
State Reference	IN
Altitude	msl bound lower : 23000 msl bound upper : 23300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 100 flight time total : 12000 flight time type : 25
ASRS Report	318540
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Autoplt failed to level aircraft at 23000 ft. PF took control and leveled at 23300 ft then descended to FL230. Autoplt armed function dropped out for unknown reasons causing no altitude capture in automatic-mode. Approaching desired altitude ensure autoplt armed for capture.

Original NASA ASRS Text

Title: WDB CLBS ABOVE ASSIGNED ALT DUE TO FAILURE OF AUTOPLT TO CAPTURE.

Narrative: AUTOPLT FAILED TO LEVEL ACFT AT 23000 FT. PF TOOK CTL AND LEVELED AT 23300 FT THEN DSNDED TO FL230. AUTOPLT ARMED FUNCTION DROPPED OUT FOR UNKNOWN REASONS CAUSING NO ALT CAPTURE IN AUTO-MODE. APCHING DESIRED ALT ENSURE AUTOPLT ARMED FOR CAPTURE.

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.