Date: 201704
Local time of day: 0001-0600
Location: ZLA.ARTCC, CA
Aircraft: Airbus Industrie Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZLA
ATC / advisory: Center ZLA
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Confusion; Distraction; Human-Machine Interface; Situational Awareness; Workload
Second reporter function: Enroute
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Contributing factors: Equipment / Tooling; Procedure; Human Factors
Primary problem: Equipment / Tooling

Narrative: This is more a safety problem than a safety event; but an event also occurred because of the safety problem.Aircraft X was in level flight at FL240; and was issued a clearance to descend via the HLYWD1 arrival. The aircraft was well before the BRUEN altitude window at 240B300; but the pilot reported leaving FL240. The controller immediately caught the read back; told the pilot to maintain FL240; and I was told that Mode-C did not indicate the aircraft leaving FL240.The aircraft was issued the Brasher Warning by me on the next sector's frequency (I was working the low altitude sector at the time of the incident); and upon landing at LAX; the pilot and co-pilot called me as requested. The pilots didn't really have much useful information to add.As a general trend; we have noticed that this same situation has been happening very regularly with [Airline name removed]. While this incident did not result in the aircraft busting its assigned altitude; the majority of these situations do result in altitude deviations. Being dissatisfied with the answers I was receiving from the pilots; I contacted the [Airline] Chief Pilot on Duty for the area. I had a very good and long conversation regarding what took place and why. The [Chief Pilot] explained that in Airbus aircraft; when the aircraft is in level flight (Cruise Phase according to a [specific aircraft type] systems; at FL240; for example; the altitude constraint of 240B300 would be deleted from the onboard computer; unless the aircraft climbed to a higher cruise altitude; i.e. FL280 or 300). It is up to the pilots to verify the altitude restrictions manually per the physical/electronic charts. The PFD and MCDU delete the upcoming altitude restraint; and any subsequent altitude restraints unless the window is lower than the present cruise altitude of the aircraft. [Airline] Company Policy dictates that each pilot must independently verify the altitude windows prior to descending the aircraft. That obviously did not happen in this event; and was definitely pilot error; however; what a completely stupid and useless system that deletes the altitude constraints in this fashion. [Chief Pilot] noted that the same thing would happen; for example; even on longer routes; where a pilot departing ZZZ might choose a lower altitude because of reported turbulence; etc. They might fly across the entire country at a lower altitude; and accordingly; the upcoming constraints (potentially all the way across the country in ZLA airspace) would be deleted. How can it be acceptable for an aircraft to simply delete applicable altitude constraints on an arrival? Human error is going to take place. We all know that. The two pilots on Aircraft X both independently missed the altitude constraints; and to be perfectly honest; it's a very easy thing to miss when you are in the descent phase of flight and have a lot of things going on in the cockpit. This time; there was no loss of separation (or life); but this should absolutely be corrected; as the potential for error and loss of separation is extremely high.Fix the Airbus computers so what they are doing makes sense. It's completely idiotic for the computer to delete pertinent altitude restrictions; even more so for an aircraft that loves flying itself with minimal/no pilot intervention.


Second narrative: I was working R39 and was sequencing for LAX.  Aircraft X was a PHX departure and was in level flight at FL240.  I cleared them to HLYWD and issued a descend via clearance. The aircraft was in level flight at FL240 and the restriction after HLYWD is BRUEN between FL240-300.  I assumed the aircraft would maintain FL240 until BRUEN.  About one minute after I issued the descend via clearance the aircraft checked out of their altitude to which I immediately climbed them back up and pointed them out to the low altitude sector.  When the aircraft called in to the supervisor we learned that if they are in level flight and a descend via clearance is issued the Airbus navigational equipment disregards all crossing restrictions at and above the current altitude.


Synopsis: Two ZLA Controllers reported an aircraft did not make the crossing restrictions after being cleared to descend via because of an ongoing aircraft type computer problem.