A319
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 225; Flight Crew Total 4692; Flight Crew Type 2797
Situational Awareness; Confusion; Distraction
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Regained Aircraft Control; Flight Crew FLC Overrode Automation
Aircraft
During cruise flight the autopilot commanded a descent like it was trying to capture a path from above. The aircraft descended below the selected FCU altitude so the Captain turned off the autopilot and arrested the descent where we leveled off about 1;100 feet below FCU selected altitude of FL360. We informed ATC and climbed back up to FL360. We noticed the FMGC 2 was going blank and then coming back on so we used Autopilot 1 the rest of the flight even though I was flying.
A319 First Officer reported autopilot did not maintain altitude during cruise flight.