Narrative:

During civet 1 arrival, first officer was hand-flying aircraft using VNAV commands. Bremr intersection has crossing restr at or above 12000 ft. Just prior to bremr, first officer responded to CDU message to add drag, interpreting message as need to descend faster. First officer extended speed brakes and descended below 12000 ft. I noted error at approximately 11000 ft and first officer initiated correction. I informed approach control we had dropped below 12000 ft. He said there was no traffic conflict but to maintain 11000 ft. I had been busy with checklist, PA, tuning ILS, the usual and did not totally follow progression of arrival. We do not know why CDU commanded requirement for adding drag during that phase of flight. Supplemental information from acn 354719: I was the PF. On the civet 1 arrival to lax I descended below the 12000 ft or above restr at bremr intersection while hand-flying the arrival. Once we realized the mistake I began to climb but the captain called approach control and we were told there was no conflict, descend to cross bremr at 11000 ft or above. The CDU had said drag required and I thought that meant we were not going to make our next crossing restr so I continued the descent before verifying the altitude. Callback conversation with reporter revealed the following information: reporter was hand- flying the aircraft. She was flying with a new captain who was very inquisitive about every action she was making. He just was trying to understand every aspect of managing the approach. Reporter was using a different technique of flying the aircraft, as she was descending in vertical speed which allowed the altimeter alerter to be set to lowest altitude in the approach. Had she been flying in VNAV she would have had altitude protection for all the intermediate altitudes during the approach. The captain's constant inquiry of every step that was being taken by the PF took a lot of time from planning for a busy approach. Reporter stated that the captain was very distracting.

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Original NASA ASRS Text

Title: B757 CROSSES BREMR 1000 FT LOW DURING CIVET 1 ARR TO RWY 25L ILS AT LAX.

Narrative: DURING CIVET 1 ARR, FO WAS HAND-FLYING ACFT USING VNAV COMMANDS. BREMR INTXN HAS XING RESTR AT OR ABOVE 12000 FT. JUST PRIOR TO BREMR, FO RESPONDED TO CDU MESSAGE TO ADD DRAG, INTERPRETING MESSAGE AS NEED TO DSND FASTER. FO EXTENDED SPD BRAKES AND DSNDED BELOW 12000 FT. I NOTED ERROR AT APPROX 11000 FT AND FO INITIATED CORRECTION. I INFORMED APCH CTL WE HAD DROPPED BELOW 12000 FT. HE SAID THERE WAS NO TFC CONFLICT BUT TO MAINTAIN 11000 FT. I HAD BEEN BUSY WITH CHKLIST, PA, TUNING ILS, THE USUAL AND DID NOT TOTALLY FOLLOW PROGRESSION OF ARR. WE DO NOT KNOW WHY CDU COMMANDED REQUIREMENT FOR ADDING DRAG DURING THAT PHASE OF FLT. SUPPLEMENTAL INFO FROM ACN 354719: I WAS THE PF. ON THE CIVET 1 ARR TO LAX I DSNDED BELOW THE 12000 FT OR ABOVE RESTR AT BREMR INTXN WHILE HAND-FLYING THE ARR. ONCE WE REALIZED THE MISTAKE I BEGAN TO CLB BUT THE CAPT CALLED APCH CTL AND WE WERE TOLD THERE WAS NO CONFLICT, DSND TO CROSS BREMR AT 11000 FT OR ABOVE. THE CDU HAD SAID DRAG REQUIRED AND I THOUGHT THAT MEANT WE WERE NOT GOING TO MAKE OUR NEXT XING RESTR SO I CONTINUED THE DSCNT BEFORE VERIFYING THE ALT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS HAND- FLYING THE ACFT. SHE WAS FLYING WITH A NEW CAPT WHO WAS VERY INQUISITIVE ABOUT EVERY ACTION SHE WAS MAKING. HE JUST WAS TRYING TO UNDERSTAND EVERY ASPECT OF MANAGING THE APCH. RPTR WAS USING A DIFFERENT TECHNIQUE OF FLYING THE ACFT, AS SHE WAS DSNDING IN VERT SPD WHICH ALLOWED THE ALTIMETER ALERTER TO BE SET TO LOWEST ALT IN THE APCH. HAD SHE BEEN FLYING IN VNAV SHE WOULD HAVE HAD ALT PROTECTION FOR ALL THE INTERMEDIATE ALTS DURING THE APCH. THE CAPT'S CONSTANT INQUIRY OF EVERY STEP THAT WAS BEING TAKEN BY THE PF TOOK A LOT OF TIME FROM PLANNING FOR A BUSY APCH. RPTR STATED THAT THE CAPT WAS VERY DISTRACTING.

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.