Air carrier has autoplt problem at leveloff cruise altitude.

Attributes
ACN	460720
Time
Date	200001
Day	Fri
Local Time Of Day	0601 To 1200
Place
State Reference	ON
Altitude	msl single value : 1000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 210 flight time total : 7800 flight time type : 5500
ASRS Report	460720
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Aircraft autoplt did not hold altitude on leveloff. Descended below assigned altitude 100 ft.

Original NASA ASRS Text

Title: ACR HAS AUTOPLT PROB AT LEVELOFF CRUISE ALT.

Narrative: ACFT AUTOPLT DID NOT HOLD ALT ON LEVELOFF. DSNDED BELOW ASSIGNED ALT 100 FT.

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.