Narrative:

Taxi in lax, ground control told us to call TRACON on the land line. On the telephone, the supervisor advised we descended below 10000 ft at arnes without clearance. I thought I heard 'cross bremer at 12000 ft, cleared ILS runway 25L approach.' the supervisor advised me that no loss of separation occurred and it was mostly an instructional conversation. In retrospect, would it have been better if we held at arnes? This trap at arnes was set and sprung because of the following. Told to fly 320 KTS or better, 250 KTS, 180 KTS as soon as possible, then 210 KTS. Given 2 vectors to intercept runway 25L localizer and resume civet 1. Frequency saturation, people 'stepping on each other' and traffic calls. FMC shows no route discontinuity from arnes to ILS runway 25L -- continuous route with step down fixes. New stars like civet 1 that allow pilot 'discretion dscnts' powerfully suggest that descent below 10000 ft at arnes is expected. I suggest that we examine ways to clear for civet 1, runway 25L ILS all at once, so the trap at arnes would not occur. If speed control will not handle separation, then instruct an airplane to break out of final and resequence it. Frequency saturation was a major factor in this -- it was close to no communication. I also suggest that commercial chart -- puts 'expect ILS approach' note at arnes in bold type.

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Original NASA ASRS Text

Title: ALT XING RESTR -- ACR DSNDS BELOW A MINIMUM XING ALT ON A STAR ARR.

Narrative: TAXI IN LAX, GND CTL TOLD US TO CALL TRACON ON THE LAND LINE. ON THE TELEPHONE, THE SUPVR ADVISED WE DSNDED BELOW 10000 FT AT ARNES WITHOUT CLRNC. I THOUGHT I HEARD 'CROSS BREMER AT 12000 FT, CLRED ILS RWY 25L APCH.' THE SUPVR ADVISED ME THAT NO LOSS OF SEPARATION OCCURRED AND IT WAS MOSTLY AN INSTRUCTIONAL CONVERSATION. IN RETROSPECT, WOULD IT HAVE BEEN BETTER IF WE HELD AT ARNES? THIS TRAP AT ARNES WAS SET AND SPRUNG BECAUSE OF THE FOLLOWING. TOLD TO FLY 320 KTS OR BETTER, 250 KTS, 180 KTS AS SOON AS POSSIBLE, THEN 210 KTS. GIVEN 2 VECTORS TO INTERCEPT RWY 25L LOC AND RESUME CIVET 1. FREQ SATURATION, PEOPLE 'STEPPING ON EACH OTHER' AND TFC CALLS. FMC SHOWS NO RTE DISCONTINUITY FROM ARNES TO ILS RWY 25L -- CONTINUOUS RTE WITH STEP DOWN FIXES. NEW STARS LIKE CIVET 1 THAT ALLOW PLT 'DISCRETION DSCNTS' POWERFULLY SUGGEST THAT DSCNT BELOW 10000 FT AT ARNES IS EXPECTED. I SUGGEST THAT WE EXAMINE WAYS TO CLR FOR CIVET 1, RWY 25L ILS ALL AT ONCE, SO THE TRAP AT ARNES WOULD NOT OCCUR. IF SPD CTL WILL NOT HANDLE SEPARATION, THEN INSTRUCT AN AIRPLANE TO BREAK OUT OF FINAL AND RESEQUENCE IT. FREQ SATURATION WAS A MAJOR FACTOR IN THIS -- IT WAS CLOSE TO NO COM. I ALSO SUGGEST THAT COMMERCIAL CHART -- PUTS 'EXPECT ILS APCH' NOTE AT ARNES IN BOLD TYPE.

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.