Narrative:

I was the first officer on a flight to los angeles. I was the PF. We were on the riivr 1 arrival to lax and were instructed to expect the ILS 25L; GS out of service. After crossing fuelr intersection we began the approach. We were planning on ILS runway 24R; and had already briefed the approach to that runway; so when we were given the change we had to brief quickly. I had not reviewed the approach as thoroughly as I would have liked and was not familiar with all of the step-down fixes. As we crossed fuelr inbound; I began my descent. I also thought that ATC had cleared us for the visual. Anyway; during my descent; I was trying to keep a 3 degree GS. After crossing fuelr; I calculated that I was flying above the 3 degree GS; so I increased my descent. Shortly after I realized that I was getting low and started to slow my descent; but by the time I noticed I was getting low I crossed gaate intersection about 500-700 ft low. At the time I wasn't too concerned as I thought we were cleared for the visual approach. The whole time during the approach we were in VMC and could see the runway. There was no traffic near us during the approach. As we continued on the approach; I managed to stabilize the aircraft and cross each fix at the required altitude. We landed without further incident. I will note that ATC never mentioned the altitude deviation.

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Original NASA ASRS Text

Title: LATE RWY CHANGE ON RIIVR STAR TO RWY 25L CONTRIBUTES TO ALT DEV OVER GAATE.

Narrative: I WAS THE FO ON A FLT TO LOS ANGELES. I WAS THE PF. WE WERE ON THE RIIVR 1 ARR TO LAX AND WERE INSTRUCTED TO EXPECT THE ILS 25L; GS OUT OF SVC. AFTER XING FUELR INTXN WE BEGAN THE APCH. WE WERE PLANNING ON ILS RWY 24R; AND HAD ALREADY BRIEFED THE APCH TO THAT RWY; SO WHEN WE WERE GIVEN THE CHANGE WE HAD TO BRIEF QUICKLY. I HAD NOT REVIEWED THE APCH AS THOROUGHLY AS I WOULD HAVE LIKED AND WAS NOT FAMILIAR WITH ALL OF THE STEP-DOWN FIXES. AS WE CROSSED FUELR INBOUND; I BEGAN MY DSCNT. I ALSO THOUGHT THAT ATC HAD CLRED US FOR THE VISUAL. ANYWAY; DURING MY DSCNT; I WAS TRYING TO KEEP A 3 DEG GS. AFTER XING FUELR; I CALCULATED THAT I WAS FLYING ABOVE THE 3 DEG GS; SO I INCREASED MY DSCNT. SHORTLY AFTER I REALIZED THAT I WAS GETTING LOW AND STARTED TO SLOW MY DSCNT; BUT BY THE TIME I NOTICED I WAS GETTING LOW I CROSSED GAATE INTXN ABOUT 500-700 FT LOW. AT THE TIME I WASN'T TOO CONCERNED AS I THOUGHT WE WERE CLRED FOR THE VISUAL APCH. THE WHOLE TIME DURING THE APCH WE WERE IN VMC AND COULD SEE THE RWY. THERE WAS NO TFC NEAR US DURING THE APCH. AS WE CONTINUED ON THE APCH; I MANAGED TO STABILIZE THE ACFT AND CROSS EACH FIX AT THE REQUIRED ALT. WE LANDED WITHOUT FURTHER INCIDENT. I WILL NOTE THAT ATC NEVER MENTIONED THE ALTDEV.

Data retrieved from NASA's ASRS site as of May 2009 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.