Narrative:

In descent from FL390 passing about FL360; got ECAM automatic flight FCU 1 fail. First officer was PF and autoplt #2 was engaged in navigation and managed descent. Cleared ECAM and noticed that altitude set in FCU window had changed by itself from 32000 ft to 33000 ft. We changed it back to 32000 ft and continued descent. Wrote it up in ZZZ and told maintenance what had happened. I have been on the airbus over 5 yrs and have never seen FCU altitude window setting change by itself before. I am very concerned about the potential this represents. Fortunately; we caught it right away. This could have been very bad.

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Original NASA ASRS Text

Title: A319 FLT CREW REPORTS FCU1 FAILURE DURING DESCENT CAUSING ALTITUDE SET WINDOW TO CHANGE BY ONE THOUSAND FEET.

Narrative: IN DSCNT FROM FL390 PASSING ABOUT FL360; GOT ECAM AUTO FLT FCU 1 FAIL. FO WAS PF AND AUTOPLT #2 WAS ENGAGED IN NAV AND MANAGED DSCNT. CLRED ECAM AND NOTICED THAT ALT SET IN FCU WINDOW HAD CHANGED BY ITSELF FROM 32000 FT TO 33000 FT. WE CHANGED IT BACK TO 32000 FT AND CONTINUED DSCNT. WROTE IT UP IN ZZZ AND TOLD MAINT WHAT HAD HAPPENED. I HAVE BEEN ON THE AIRBUS OVER 5 YRS AND HAVE NEVER SEEN FCU ALT WINDOW SETTING CHANGE BY ITSELF BEFORE. I AM VERY CONCERNED ABOUT THE POTENTIAL THIS REPRESENTS. FORTUNATELY; WE CAUGHT IT RIGHT AWAY. THIS COULD HAVE BEEN VERY BAD.

Data retrieved from NASA's ASRS site as of January 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.