AN AIRBUS A319 FLC DSNDED BELOW THE PROCS XING ALT ON ARR TO LAX.

Narrative

DSNDING AND ON ARR LAX. ORIGINALLY PROGRAMMED FOR THE CIVET ARR. THAT CLRNC WAS CHANGED TO THE PDZ ARR (PDZ.PDZ.3). THE REVISED CLRNC WAS PROGRAMMED INTO THE FMC FOR RWY 25R. WHEN SWITCHED TO THE APCH CTLR; WE WERE TOLD THE RWY WOULD BE RWY 25L. THE CLRNC TO DSND VIA THE PDZ ARR WAS NEVER GIVEN; AND IF GIVEN; NEVER HEARD OR ACKNOWLEDGED. APCH FREQ WAS SO BUSY I COULD NOT BREAK IN TO VERIFY THE DSCNT. DSCNT CLRNC WAS RECEIVED AND INITIATED LATE. THE FMC HAD TO BE REPROGRAMMED FOR RWY 25L AND DURING THE REPROGRAMMING PROCESS; AUTOMATED FLT SYS DISENGAGED AND REVERTED TO OPEN DSCNT MODE. THE ACFT DSNDED TO 10000 FT -- 2000 FT BELOW THE 12000 FT XING CONSTRAINT AT TEJAY. CONTRIBUTORS: 1) UNCLR AND LATE CLRNC FROM APCH CTLR. 2) REVISED CLRNCS REQUIRING FMC FLT PLAN MODIFICATION AT HIGH WORKLOAD PHASE OF FLT; IE; CHANGING STARS; RWYS. 3) SOCAL APCH NEEDS TO BE AWARE OF THE IMPACT ON COCKPIT WORKLOAD WITH THE MANY CHANGES DURING ARR. 4) PF WAS NEW CAPT ON ACFT. I WAS CHK AIRMAN CONDUCTING IOE. I WAS HEADS DOWN PROGRAMMING WHEN REVERSION OCCURRED.