An A319/20 captain reported the failure of the aircraft's FMGC and autoflight systems to comply with...

Narrative:

Leaving FL300 we were cleared to descend via the frdmm STAR into dca. The first officer engaged the des mode and managed speed after I set the bottom altitude in the MCP. We verified the restrictions on the mcdu and on the nd. After making the first several crossings with no problem; the first officer and I briefed the approach. At this time the autopilot seemed to 'go dumb' and continued descending below the next crossing altitude. The FMA still indicated des mode engaged; but the autopilot was descending below profile. The first officer disengaged the autopilot and climbed the jet to meet the restriction. The doughnut and the prog page displayed correct information; but the autopilot was not maintaining the profile. We then reverted to the old way of setting the most restrictive altitude and the cockpit workload went through the roof as there are 15 altitude and 5 airspeed restrictions on this arrival. We attempted des mode again and it made the altitude crossings; but would not make the airspeed restrictions even though we were in managed speed. We used selected speed to comply with the restrictions.upon landing; we entered an item for the malfunction and called maintenance control. A mechanic reset the fmgcs and we flew the airplane again; but did not have the opportunity to use des mode on the the following flight. I have seen this problem several times on the airbus; the autopilot disregards FMGC profiles.

Original NASA ASRS Text

Title: An A319/20 Captain reported the failure of the aircraft's FMGC and autoflight systems to comply with the altitude and airspeed restrictions while conducting the FRDMM RNAV STAR to DCA.

Narrative: Leaving FL300 we were cleared to descend via the FRDMM STAR into DCA. The First Officer engaged the DES mode and managed speed after I set the bottom altitude in the MCP. We verified the restrictions on the MCDU and on the ND. After making the first several crossings with no problem; the First Officer and I briefed the approach. At this time the autopilot seemed to 'go dumb' and continued descending below the next crossing altitude. The FMA still indicated DES mode engaged; but the autopilot was descending below profile. The First Officer disengaged the autopilot and climbed the jet to meet the restriction. The doughnut and the PROG page displayed correct information; but the autopilot was not maintaining the profile. We then reverted to the old way of setting the most restrictive altitude and the cockpit workload went through the roof as there are 15 altitude and 5 airspeed restrictions on this arrival. We attempted DES mode again and it made the altitude crossings; but would not make the airspeed restrictions even though we were in managed speed. We used selected speed to comply with the restrictions.Upon landing; we entered an item for the malfunction and called Maintenance Control. A Mechanic reset the FMGCs and we flew the airplane again; but did not have the opportunity to use DES mode on the the following flight. I have seen this problem several times on the Airbus; the autopilot disregards FMGC profiles.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1038967
Time
Date	201209
Local Time Of Day	1201-1800
Place
Locale Reference	ZDC.ARTCC
State Reference	VA
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach Descent
Route In Use	STAR FRDMM RNAV
Flight Plan	IFR
Component
Aircraft Component	Autoflight System
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 220 Flight Crew Total 19500 Flight Crew Type 4000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

An A319/20 captain reported the failure of the aircraft's FMGC and autoflight systems to comply with the altitude and airspeed restrictions while conducting the frdmm RNAV STAR to dca.