B727-232 has autoplt malfunction in the altitude hold position.

Attributes
ACN	332970
Time
Date	199603
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : fam
State Reference	MO
Altitude	msl bound lower : 33000 msl bound upper : 33600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 163 flight time total : 6300 flight time type : 4000
ASRS Report	332970
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Cruising at FL330 over fam VOR the airplane started an uncommanded climb, the B727 has a 'block V' autoplt, altitude capture and hold. The autoplt was engaged and the altitude hold light was illuminated. The B727 climbed to FL336 with the autoplt engaged and the altitude hold light illuminated. Airplane control was regained by disconnecting the autoplt. We returned to FL330, engaged the autoplt and had an uneventful remainder flight.

Original NASA ASRS Text

Title: B727-232 HAS AUTOPLT MALFUNCTION IN THE ALT HOLD POS.

Narrative: CRUISING AT FL330 OVER FAM VOR THE AIRPLANE STARTED AN UNCOMMANDED CLB, THE B727 HAS A 'BLOCK V' AUTOPLT, ALT CAPTURE AND HOLD. THE AUTOPLT WAS ENGAGED AND THE ALT HOLD LIGHT WAS ILLUMINATED. THE B727 CLBED TO FL336 WITH THE AUTOPLT ENGAGED AND THE ALT HOLD LIGHT ILLUMINATED. AIRPLANE CTL WAS REGAINED BY DISCONNECTING THE AUTOPLT. WE RETURNED TO FL330, ENGAGED THE AUTOPLT AND HAD AN UNEVENTFUL REMAINDER FLT.

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.