A320 SPD DEV WHILE DEALING WITH ARR CHANGE AT LAX.

Narrative

WE WERE ACR FLT XX APCHING PDZ VOR ON THE PDZ 2 ARR FOR RWY 25L AT LAX. WE WERE DSNDING OUT OF 16000 FT FOR 12000 FT. PDZ 2 WAS OUR FLT PLAN CLRNC STAR AND WE HAD LOADED THE ILS RWY 25L FOR LNDG AS THAT WAS THE LOGICAL FOR THAT STAR AND THE ATIS OUR DIRECTION. OUTSIDE PDZ VOR WE WERE TOLD TO EXPECT MITTS 1 ARR AND RWY 24R. UPON HEARING THIS WE STARTED TO PREPARE FOR THE CHANGE. THIS REQUIRED THE CAPT (PNF) TO BE HEADS DOWN RELOADING THE FMGC WITH THE NEW ARR AND RWY. A TIME CONSUMING PROCESS AT THIS TIME IN THE FLT; ESPECIALLY IN THE A320. I HAD TO PULL OUT THE NEW ARR AND APCH CHART TO FAMILIARIZE MYSELF AND REBRIEF. APCHING TEJAY INTXN WE RECEIVED CLRNC FOR THE MITTS 1 ARR. HOWEVER; I DID NOT HEAR THE CLRNC OR IT DID NOT REGISTER SO I MAINTAINED OUR PREVIOUSLY CLRED ALT 12000 FT. THE CAPT WAS STILL QUITE BUSY LOADING THE FMGC. I WAS ALSO TRYING TO FAMILIARIZE MYSELF WITH THE NEW APCH/RWY XING RESTRS. APPROX 6 MI OUTSIDE MITTS; THE CAPT REMINDED ME WE WERE CLRED FOR ARR. I WAS BEHIND AND DISENGAGED THE AUTOPLT AND SELECTED 300 KTS ON FCU AND DEPLOYED SPD BRAKES TO MAKE XING RESTRS. I FORGOT ABOUT MY SPD. AT AROUND 9000 FT CAPT CALLED OUT MY SPD. I PROMPTLY CALLED FOR 250 KTS AND SLOWED. POOR SITUATIONAL AWARENESS BY MYSELF; TOO ENGROSSED IN XING RESTRS; FORGOT TO SLOW AT 10000 FT; FAILURE TO RE-ENGAGE AUTOPLT TO LESSEN WORKLOAD. LATE CHANGE BY ATC IN A VERY DEMANDING ENVIRONMENT. WE NEED THESE CHANGES MUCH EARLIER WITH THIS ACFT AS TECHNOLOGY CAN MAKE THINGS EASIER; BUT IT DOES TAKE LONGER TO RELOAD CHANGES IN THE FMS.