Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Human-Machine Interface; Confusion
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation - Speed All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation; Flight Crew Returned To Clearance
Procedure; Human Factors
Both the first officer (pilot flying) and I (pilot monitoring) earlier in the flight briefed and verified with the aircraft flight management system the RIIVR2 arrival and ILS Runway 25L approach in LAX. We were then cleared by ATC to proceed the RIIVR2 arrival to ILS 25L LAX. LA Center advised us that we were the lead arrival airplane and to keep our speed up to 300 knots or greater. We were then cleared to proceed direct to Gramm intersection and cross Gramm at FL180 and 280 knots and handed off to SoCal approach. We complied with the restriction at Gramm intersection and then received an amended clearance to proceed direct to Krain intersection and initially cleared to descend to 14;000 feet and to keep our speed up.Our next clearance was to cross Krain at 10;000 feet and cleared the ILS 25L. We were then given clearance to reduce speed to 250 knots. The airplane was in managed descent mode and the crossing altitude of 1900 feet at Limma intersection was set in the FCU. As we descended through approximately 10;500 feet the airplane made an unexpected aggressive roll to the left. Both the first officer and I assessed the situation and were figuring out why the airplane was making the unexpected left turn when I noticed the approach arm button had been activated which changes the managed descent mode. I then asked the first officer to disarm approach mode and by the time this was done the airplane had descended through 10;000 feet prior to Krain intersection and our speed was above 250 knots. We stopped descent; re-engaged nav mode and slowed the aircraft. There was no other traffic in our area. The remainder of the approach proceeded in a normal manner.
[Report narrative contained no additional information.]
A321 flight crew reported selecting approach mode early on the LAX RIIVR2 causing an unplanned turn to the unstable localizer signal. Crew overrode the automation and corrected back to the proper course.