Narrative:

Arriving at lax enroute approaching [late evening]; we were originally assigned the SEAVU2 arrival landing west. I was pilot monitoring; and giving my arrival PA. As I was making announcement; the first officer received a new clearance; the rdeye arrival landing east. She put the new arrival in the FMGC. We were cleared to descend to 17000 ft at konzl intersection. As I finished my PA; I acknowledged the new clearance with first officer. ATC then changed us back to the SEAVU2 arrival landing west and the first officer loaded the information into FMGC. As we accomplished this task; we passed konzl intersection still at 17;000 ft cleared for the ILS 25L. We had 24R programmed; so we had to make a quick change to 25L. We did that; but we were still not cleared to descend and getting very high as we were reprogramming the FMGC. We overshot the 25L localizer; but quickly turned to the left to avoid conflict. I tried to enter a direct to gaate intersection; but the FMGC would not accept any input from my side. I took control of the aircraft and the first officer attempted to input the FMGC. Still no acceptance of input. I turned off autopilot and hand flew aircraft. We asked to be vectored off the arrival; but they said you're high; but you'll be okay.now we are high; trying to reconfigure FMGC; and ATC gives us s-turns to try to get on profile. We're still high; so ATC gives us a turn to the left and descent to 4000 ft. We did that but with all the task loading and high workload; we descended to 3700 ft. ATC asked why we went below 4000 ft. We told them high workload and corrected our altitude. They vectored us to the 25L localizer and [we] landed uneventful.two arrival changes below 18000 ft too close to the airport; high task loading; confusion with runway assignment; 3rd leg on a pairing after midnight.

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Original NASA ASRS Text

Title: A321 flight crew reported a track deviation and altitude overshoot resulted from task saturation on arrival into LAX as ATC changed the runway and arrival clearances several times.

Narrative: Arriving at LAX enroute approaching [late evening]; we were originally assigned the SEAVU2 arrival landing west. I was pilot monitoring; and giving my arrival PA. As I was making announcement; the First Officer received a new clearance; the RDEYE arrival landing east. She put the new arrival in the FMGC. We were cleared to descend to 17000 ft at KONZL intersection. As I finished my PA; I acknowledged the new clearance with First Officer. ATC then changed us back to the SEAVU2 arrival landing west and the First Officer loaded the information into FMGC. As we accomplished this task; we passed KONZL intersection still at 17;000 ft cleared for the ILS 25L. We had 24R programmed; so we had to make a quick change to 25L. We did that; but we were still not cleared to descend and getting very high as we were reprogramming the FMGC. We overshot the 25L localizer; but quickly turned to the left to avoid conflict. I tried to enter a direct to GAATE intersection; but the FMGC would not accept any input from my side. I took control of the aircraft and the First Officer attempted to input the FMGC. Still no acceptance of input. I turned off Autopilot and hand flew aircraft. We asked to be vectored off the arrival; but they said you're high; but you'll be okay.Now we are high; trying to reconfigure FMGC; and ATC gives us S-Turns to try to get on profile. We're still high; so ATC gives us a turn to the left and descent to 4000 ft. We did that but with all the task loading and high workload; we descended to 3700 ft. ATC asked why we went below 4000 ft. We told them high workload and corrected our altitude. They vectored us to the 25L localizer and [we] landed uneventful.Two arrival changes below 18000 ft too close to the airport; high task loading; confusion with runway assignment; 3rd leg on a pairing after midnight.

Data retrieved from NASA's ASRS site 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.