Altitude deviation altitude excursion.

Attributes
ACN	220420
Time
Date	199209
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : onl
State Reference	NE
Altitude	msl bound lower : 33000 msl bound upper : 34000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 3500 flight time type : 150
ASRS Report	220420
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : instrument pilot : atp
Experience	flight time last 90 days : 35 flight time total : 7000 flight time type : 200
ASRS Report	220640
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : returned to intended course or assigned course flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

The aircraft, a widebody transport cargo, was at FL330 in cruise, 'a' autoplt in command mode with altitude hold. While in IMC, the autoplt executed an uncommanded pitch up of 10 degrees or more. The aircraft gained 1000 ft before the captain (the PF) recovered control and returned to altitude. The crew could not have acted quickly enough to overcome such an abrupt autoplt input. With the past history of widebody transport X autoplts an airworthiness directive or other corrective action should be taken. Supplemental information from acn 220640: a second engagement of a autoplt resulted in a repeated pitch up. 'A' autoplt was written up in aircraft log and not used for remainder of flight. No previous write-ups.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION.

Narrative: THE ACFT, A WDB CARGO, WAS AT FL330 IN CRUISE, 'A' AUTOPLT IN COMMAND MODE WITH ALT HOLD. WHILE IN IMC, THE AUTOPLT EXECUTED AN UNCOMMANDED PITCH UP OF 10 DEGS OR MORE. THE ACFT GAINED 1000 FT BEFORE THE CAPT (THE PF) RECOVERED CTL AND RETURNED TO ALT. THE CREW COULD NOT HAVE ACTED QUICKLY ENOUGH TO OVERCOME SUCH AN ABRUPT AUTOPLT INPUT. WITH THE PAST HISTORY OF WDB X AUTOPLTS AN AIRWORTHINESS DIRECTIVE OR OTHER CORRECTIVE ACTION SHOULD BE TAKEN. SUPPLEMENTAL INFO FROM ACN 220640: A SECOND ENGAGEMENT OF A AUTOPLT RESULTED IN A REPEATED PITCH UP. 'A' AUTOPLT WAS WRITTEN UP IN ACFT LOG AND NOT USED FOR REMAINDER OF FLT. NO PREVIOUS WRITE-UPS.

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.