Narrative:

Air carrier xyz slc-lax. Our clearance was for civet 4 into lax. We had been cleared to FL180 and we were passing through approximately FL220 approaching civet (approximately 10-15 NM). Runway 25L was briefed using civet 4. Lax calls and gives mitts 1 to runway 24R because of traffic. The autoplt was on and the PF was the first officer, who elected to program the autoplt. The STAR was pulled out and runway 24R ILS approach was also pulled out. The clearance was mitts 1 direct snrkl at or above 12000 ft. Descend via mitts 1. The FMS was programmed for mitts 1 but snrkl wasn't showing. Captain suggested civet transition which when selected showed snrkl. Aircraft direct snrkl. There had been numerous airspeed changes, ie, 300 KTS, 280 KTS, 250 KTS, and at some point the aircraft had been taken out of VNAV and 250 KTS set manually (250 KTS also set in descent page), LNAV was engaged, runway 24R briefed. I don't know if the PNF set 250 KTS manually or I did. I don't remember doing it, things were happening fast. Approaching mitts (11000 B, 10000 a) it appeared that the aircraft was going to descend below 10000 ft (not in VNAV and altitude set for denay at 8000 ft). Altitude hold selected, at which point I noted that the aircraft wasn't in VNAV. Aircraft descended to about 9600 ft before I climbed back towards 10000 ft. At mitts, reinitiated descent for normal approach. Once I pointed out we had descended below 10000 ft, the captain noted we hadn't done descent or approach checklists (although all items had been completed except altimeter -- 9600 ft at 29.92 vice 30.17). Causal factors: 1) last min STAR change. 2) PF programmed FMS instead of PNF. 3) numerous airspeed changes. 4) aircraft in manual speed instead of VNAV. 5) poor crew coordination. 6) PF didn't call for checklists, didn't back up. 7) confusion and time crunch. Note: lax is starting to do this a lot. We obviously could have handled it better.

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Original NASA ASRS Text

Title: B757 FLC ERRONEOUSLY DSNDED BELOW 10000 FT WITHOUT PROPER CLRNC ON CIVET ARR TO LAX, CA.

Narrative: ACR XYZ SLC-LAX. OUR CLRNC WAS FOR CIVET 4 INTO LAX. WE HAD BEEN CLRED TO FL180 AND WE WERE PASSING THROUGH APPROX FL220 APCHING CIVET (APPROX 10-15 NM). RWY 25L WAS BRIEFED USING CIVET 4. LAX CALLS AND GIVES MITTS 1 TO RWY 24R BECAUSE OF TFC. THE AUTOPLT WAS ON AND THE PF WAS THE FO, WHO ELECTED TO PROGRAM THE AUTOPLT. THE STAR WAS PULLED OUT AND RWY 24R ILS APCH WAS ALSO PULLED OUT. THE CLRNC WAS MITTS 1 DIRECT SNRKL AT OR ABOVE 12000 FT. DSND VIA MITTS 1. THE FMS WAS PROGRAMMED FOR MITTS 1 BUT SNRKL WASN'T SHOWING. CAPT SUGGESTED CIVET TRANSITION WHICH WHEN SELECTED SHOWED SNRKL. ACFT DIRECT SNRKL. THERE HAD BEEN NUMEROUS AIRSPD CHANGES, IE, 300 KTS, 280 KTS, 250 KTS, AND AT SOME POINT THE ACFT HAD BEEN TAKEN OUT OF VNAV AND 250 KTS SET MANUALLY (250 KTS ALSO SET IN DSCNT PAGE), LNAV WAS ENGAGED, RWY 24R BRIEFED. I DON'T KNOW IF THE PNF SET 250 KTS MANUALLY OR I DID. I DON'T REMEMBER DOING IT, THINGS WERE HAPPENING FAST. APCHING MITTS (11000 B, 10000 A) IT APPEARED THAT THE ACFT WAS GOING TO DSND BELOW 10000 FT (NOT IN VNAV AND ALT SET FOR DENAY AT 8000 FT). ALT HOLD SELECTED, AT WHICH POINT I NOTED THAT THE ACFT WASN'T IN VNAV. ACFT DSNDED TO ABOUT 9600 FT BEFORE I CLBED BACK TOWARDS 10000 FT. AT MITTS, REINITIATED DSCNT FOR NORMAL APCH. ONCE I POINTED OUT WE HAD DSNDED BELOW 10000 FT, THE CAPT NOTED WE HADN'T DONE DSCNT OR APCH CHKLISTS (ALTHOUGH ALL ITEMS HAD BEEN COMPLETED EXCEPT ALTIMETER -- 9600 FT AT 29.92 VICE 30.17). CAUSAL FACTORS: 1) LAST MIN STAR CHANGE. 2) PF PROGRAMMED FMS INSTEAD OF PNF. 3) NUMEROUS AIRSPD CHANGES. 4) ACFT IN MANUAL SPD INSTEAD OF VNAV. 5) POOR CREW COORD. 6) PF DIDN'T CALL FOR CHKLISTS, DIDN'T BACK UP. 7) CONFUSION AND TIME CRUNCH. NOTE: LAX IS STARTING TO DO THIS A LOT. WE OBVIOUSLY COULD HAVE HANDLED IT BETTER.

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.