A320
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Total 20000
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Altitude Overshoot; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Flight Crew Became Reoriented
Aircraft; Human Factors
Flight to ZZZ; filed and cleared FL230. While in the cruise phase we decided to climb up to FL250 in the attempt to get above the clouds. Another aircraft reported moderate rime ice in the area so I was monitoring the icing probe and conditions. We were then cleared DIRECT to ZZZZZ and to descend via the [arrival] landing north. The Captain had briefed the arrival and stated we would start down at TOD.On the descent profile we ended crossing ZZZZZ [which has a charted minimum altitude of FL240] at 23500-ish. ATC advised us of our deviation and we stopped our descent and discussed with ATC. We then continued our descent on the arrival.Conditions during the event Night IMC in icing conditions. When we changed altitudes from FL230 to FL250 we were now above the crossing constraints at ZZZZZ but because we had reviewed the arrival prior climbing; the constraint at ZZZZZ wasn't displayed because we were below it. If the Airbus system hadn't deleted the constraint we would have seen it and trapped the error. I don't understand why the Airbus will remove restrictions on an arrival but not on an ILS.Had we stayed at FL230 we would have crossed ZZZZZ below the published restriction but legal because we never went above FL240.The Airbus FMS system is flawed and it is a widely known programming error in the system. On every flight release it even states that there is a problem in the program. The responsibility has been placed squarely on the backs of the pilots to catch all of the Airbus altitude Nav failures. As a pilot on the Airbus for [many] years I have never missed an altitude crossing restriction. ZZZ has so many altitude windows on the STAR it's very likely that most pilots will bust an altitude restriction eventually.Upgrading to the latest FMS nav system program on the Airbus system might solve the altitude deviation problems. If this is not fixed it's the pilots who are the last line of defense.
A320 Captain reported overshooting a crossing restriction on arrival; citing a known Airbus FMS issue as contributing.