Narrative:

We were cleared the ILS runway 25L lax and had adhered to all the step-down altitudes while using control wheel pitch and altitude hold for the dscnts and crossing altitudes. I noted that the GS was pretty much being followed and was about the same as the altitudes at the step-down fixes. (The altitude required at the step-down and the GS intersected at the fixes.) I decided to select the approach mode (autoplt captures GS) after gaate intersection and had in mind to make sure the aircraft didn't descend below the altitude limit of 3500 ft at hunda intersection. I checked the map display DME and at approximately .2 (two tenths) of a mi from hunda I felt like the aircraft would not go below the 3500 ft altitude limit at hunda. I think we were approximately 3600 ft at that point. I looked down at my approach plate (it was to my left sitting on top of my flight case) to check the next step-down altitude fix and verify the required altitude at hunda. As I was starting to look up at the ADI and HSI approach said 'cancel approach clearance, maintain 3500 ft.' I looked at my map display and noted I was inside hunda and then I looked at my altitude and it was at 3270 ft (approximately). I began a climb to 3500 ft and at 3350 ft approach reclred us for the ILS runway 25L. We were VMC at the time, but the ATIS was calling for ILS to visuals. Contributing factors were the step altitudes match the GS altitudes at most other intersections on the ILS runway 25L lax. This gives you the perception that all will do that. Another factor was that I had put the approach plate on my flight case to my left, I usually (always in full ILS approachs) put the plate in front of me.

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Original NASA ASRS Text

Title: AN ACR FLC IN AN MLG DSNDED BELOW A XING ALT. NO APPARENT CONFLICT.

Narrative: WE WERE CLRED THE ILS RWY 25L LAX AND HAD ADHERED TO ALL THE STEP-DOWN ALTS WHILE USING CTL WHEEL PITCH AND ALT HOLD FOR THE DSCNTS AND XING ALTS. I NOTED THAT THE GS WAS PRETTY MUCH BEING FOLLOWED AND WAS ABOUT THE SAME AS THE ALTS AT THE STEP-DOWN FIXES. (THE ALT REQUIRED AT THE STEP-DOWN AND THE GS INTERSECTED AT THE FIXES.) I DECIDED TO SELECT THE APCH MODE (AUTOPLT CAPTURES GS) AFTER GAATE INTXN AND HAD IN MIND TO MAKE SURE THE ACFT DIDN'T DSND BELOW THE ALT LIMIT OF 3500 FT AT HUNDA INTXN. I CHKED THE MAP DISPLAY DME AND AT APPROX .2 (TWO TENTHS) OF A MI FROM HUNDA I FELT LIKE THE ACFT WOULD NOT GO BELOW THE 3500 FT ALT LIMIT AT HUNDA. I THINK WE WERE APPROX 3600 FT AT THAT POINT. I LOOKED DOWN AT MY APCH PLATE (IT WAS TO MY L SITTING ON TOP OF MY FLT CASE) TO CHK THE NEXT STEP-DOWN ALT FIX AND VERIFY THE REQUIRED ALT AT HUNDA. AS I WAS STARTING TO LOOK UP AT THE ADI AND HSI APCH SAID 'CANCEL APCH CLRNC, MAINTAIN 3500 FT.' I LOOKED AT MY MAP DISPLAY AND NOTED I WAS INSIDE HUNDA AND THEN I LOOKED AT MY ALT AND IT WAS AT 3270 FT (APPROX). I BEGAN A CLB TO 3500 FT AND AT 3350 FT APCH RECLRED US FOR THE ILS RWY 25L. WE WERE VMC AT THE TIME, BUT THE ATIS WAS CALLING FOR ILS TO VISUALS. CONTRIBUTING FACTORS WERE THE STEP ALTS MATCH THE GS ALTS AT MOST OTHER INTERSECTIONS ON THE ILS RWY 25L LAX. THIS GIVES YOU THE PERCEPTION THAT ALL WILL DO THAT. ANOTHER FACTOR WAS THAT I HAD PUT THE APCH PLATE ON MY FLT CASE TO MY L, I USUALLY (ALWAYS IN FULL ILS APCHS) PUT THE PLATE IN FRONT OF ME.

Data retrieved from NASA's ASRS site as of July 2007 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.