B737-300 autoplt fails to capture assigned altitude.

Attributes
ACN	434290
Time
Date	199904
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : fqf.vortac
State Reference	CO
Altitude	msl bound lower : 18500 msl bound upper : 19000
Environment
Flight Conditions	VMC
Weather Elements	Windshear Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 200 flight time total : 5000 flight time type : 800
ASRS Report	430290
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 8000 flight time type : 2000
ASRS Report	434573
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned airspace
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During descent, autoplt failed to level at assigned altitude of FL190. PF recovered at approximately FL185 and immediately climbed back to FL190. We watched the autoplt closely for the rest of the flight and it seemed to operate normally. Possible cause was the steepness of the descent (approximately 3000 FPM) combined with light to moderate turbulence.

Original NASA ASRS Text

Title: B737-300 AUTOPLT FAILS TO CAPTURE ASSIGNED ALT.

Narrative: DURING DSCNT, AUTOPLT FAILED TO LEVEL AT ASSIGNED ALT OF FL190. PF RECOVERED AT APPROX FL185 AND IMMEDIATELY CLBED BACK TO FL190. WE WATCHED THE AUTOPLT CLOSELY FOR THE REST OF THE FLT AND IT SEEMED TO OPERATE NORMALLY. POSSIBLE CAUSE WAS THE STEEPNESS OF THE DSCNT (APPROX 3000 FPM) COMBINED WITH LIGHT TO MODERATE TURB.

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.