<< >> NASA ASRS Report 505781, March 2001

B737-200 flight crew experienced an uncommanded climb due to the autoplt trying to keep aircraft control in response to a stabilizer elevator control system malfunction.

Attributes
ACN	505781
Time
Date	200103
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : diw.ndb
State Reference	NC
Altitude	msl bound lower : 33300 msl single value : 33000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zdc.artcc tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Navigation In Use	other ndb
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 190 flight time total : 11000 flight time type : 4800
ASRS Report	505781
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : overcame equipment problem flight crew : returned to assigned altitude
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

In cruise flight, an elevator/stabilizer malfunction caused an uncommanded climb. Autoplt had to be disconnected and aircraft manually flown back to assigned altitude. Total deviation was about 300 ft high. Later in the flight, the aircraft entered oscillations at 100-300 ft. Emergency declared, block altitudes were cleared by ATC and we diverted the aircraft to atl. A flight control malfunction was determined to be the cause.

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Original NASA ASRS Text

Title: B737-200 FLC EXPERIENCED AN UNCOMMANDED CLB DUE TO THE AUTOPLT TRYING TO KEEP ACFT CTL IN RESPONSE TO A STABILIZER ELEVATOR CTL SYS MALFUNCTION.

Narrative: IN CRUISE FLT, AN ELEVATOR/STABILIZER MALFUNCTION CAUSED AN UNCOMMANDED CLB. AUTOPLT HAD TO BE DISCONNECTED AND ACFT MANUALLY FLOWN BACK TO ASSIGNED ALT. TOTAL DEV WAS ABOUT 300 FT HIGH. LATER IN THE FLT, THE ACFT ENTERED OSCILLATIONS AT 100-300 FT. EMER DECLARED, BLOCK ALTS WERE CLRED BY ATC AND WE DIVERTED THE ACFT TO ATL. A FLT CTL MALFUNCTION WAS DETERMINED TO BE THE CAUSE.

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.