An A320 flight crew climbed through their assigned altitude when the altitude capture feature of the...

Attributes
ACN	808579
Time
Date	200810
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zlc.artcc
State Reference	UT
Altitude	msl bound lower : 37000 msl bound upper : 37400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc tower : mlb.tower
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	808579
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	808580
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 altitude
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance

Narrative:

On a climb abeam couts intersection autoplt #2 did not capture altitude to FL370; instead at 37000 ft it changed to 3600 FPM vertical climb mode. I was able to disconnect autoplt; by that time plane had rapidly climbed to FL374; I returned by hand flying back to assigned altitude FL370. After that we used only autoplt #1. And it worked fine. Supplemental information from acn 808580: #2 autoplt was written up as inoperative and maintenance notified.

Original NASA ASRS Text

Title: AN A320 FLIGHT CREW CLIMBED THROUGH THEIR ASSIGNED ALTITUDE WHEN THE ALTITUDE CAPTURE FEATURE OF THE AUTOPILOT FAILED.

Narrative: ON A CLB ABEAM COUTS INTXN AUTOPLT #2 DID NOT CAPTURE ALT TO FL370; INSTEAD AT 37000 FT IT CHANGED TO 3600 FPM VERT CLB MODE. I WAS ABLE TO DISCONNECT AUTOPLT; BY THAT TIME PLANE HAD RAPIDLY CLBED TO FL374; I RETURNED BY HAND FLYING BACK TO ASSIGNED ALT FL370. AFTER THAT WE USED ONLY AUTOPLT #1. AND IT WORKED FINE. SUPPLEMENTAL INFO FROM ACN 808580: #2 AUTOPLT WAS WRITTEN UP AS INOP AND MAINT NOTIFIED.

Data retrieved from NASA's ASRS site as of May 2009 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.

An A320 flight crew climbed through their assigned altitude when the altitude capture feature of the autopilot failed.