Narrative:

About a hundred mi west of lax, approach control informed us to expect a straight-in approach to lax, landing to the east, expect runway 7. While I was on company frequency I was unable to monitor the captain's communication with ATC. However, during this time the first officer initiated a descent, which indicated what we had been cleared to depart out altitude. Approximately 40-50 mi from lax I heard ATC vector another aircraft into position for a landing on runway 25 (landing to the west). I decided to listen to the ATIS to see if there was a change of landing direction (which there was). While listening to the ATIS I again could not monitor the radio communication with ATC, but I noticed that the first officer had put 6000' into the altitude alerter. I finished listening to the ATIS and began monitoring ATC again just as we were being told that lax was in the process of changing runways, landing to the west, and that we were to turn left for a vector to 'sadde' for a sadde approach to lax. We headed for sadde using our FMS point-to-point navigation system. Approaching 8000' in our descent, ATC expressed concern about our altitude and said that we should be at 10000'. The captain said that we had last been cleared to 6000'. After a few moments, ATC told us to remain at 8000'. The controller then asked another aircraft if he had us in sight (he did), and requested that he expedite his climb through 10000'.

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Original NASA ASRS Text

Title: LAX APCH CTLR QUESTIONED FLT CREW OF WDB DESCENDING BELOW 10000' MSL.

Narrative: ABOUT A HUNDRED MI W OF LAX, APCH CTL INFORMED US TO EXPECT A STRAIGHT-IN APCH TO LAX, LNDG TO THE E, EXPECT RWY 7. WHILE I WAS ON COMPANY FREQ I WAS UNABLE TO MONITOR THE CAPT'S COM WITH ATC. HOWEVER, DURING THIS TIME THE F/O INITIATED A DSCNT, WHICH INDICATED WHAT WE HAD BEEN CLRED TO DEPART OUT ALT. APPROX 40-50 MI FROM LAX I HEARD ATC VECTOR ANOTHER ACFT INTO POS FOR A LNDG ON RWY 25 (LNDG TO THE W). I DECIDED TO LISTEN TO THE ATIS TO SEE IF THERE WAS A CHANGE OF LNDG DIRECTION (WHICH THERE WAS). WHILE LISTENING TO THE ATIS I AGAIN COULD NOT MONITOR THE RADIO COM WITH ATC, BUT I NOTICED THAT THE F/O HAD PUT 6000' INTO THE ALT ALERTER. I FINISHED LISTENING TO THE ATIS AND BEGAN MONITORING ATC AGAIN JUST AS WE WERE BEING TOLD THAT LAX WAS IN THE PROCESS OF CHANGING RWYS, LNDG TO THE W, AND THAT WE WERE TO TURN LEFT FOR A VECTOR TO 'SADDE' FOR A SADDE APCH TO LAX. WE HEADED FOR SADDE USING OUR FMS POINT-TO-POINT NAV SYS. APCHING 8000' IN OUR DSCNT, ATC EXPRESSED CONCERN ABOUT OUR ALT AND SAID THAT WE SHOULD BE AT 10000'. THE CAPT SAID THAT WE HAD LAST BEEN CLRED TO 6000'. AFTER A FEW MOMENTS, ATC TOLD US TO REMAIN AT 8000'. THE CTLR THEN ASKED ANOTHER ACFT IF HE HAD US IN SIGHT (HE DID), AND REQUESTED THAT HE EXPEDITE HIS CLB THROUGH 10000'.

Data retrieved from NASA's ASRS site as of August 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.