Narrative:

On descent into oak we were at 8000 ft and cleared to 5000 ft. Passing 7200 ft we were told to maintain 7000 ft. I disengaged the autoplt and leveled the aircraft at 7000 ft. I then re-engaged the autoplt. We were then reclred to 5000 ft, assigned a speed of 180 KTS and asked to expedite the descent. In an effort to go down and slow down we fully configured. We were given a heading and cleared for the ILS to runway 29, maintain 2500 ft until established. I set the intercept heading in the heading select window and 2500 ft in the altitude select window. Since we were still quite a distance from the fap, approaching 2500 ft we returned the flaps to 20 degrees. At localizer the first officer set the runway heading in the heading select window. At some point in time he also set the missed approach altitude of 4000 ft in the altitude select window which I was unaware of. The autoplt never captured the 2500 ft and the aircraft continued to descend to 1900 ft before the first officer called the deviation to my attention. I returned the aircraft to 2000 ft until the GS was captured inside of alvar intersection. The strange thing about the incident is that I don't have any memory of descending below 2500 ft until the first officer spoke up. I think there is a possibility that I fell asleep. As to what led up to this occurrence there are several factors. First and foremost was fatigue on the part of myself and the first officer. Due to the trip scheduling we both had had only 2 hours sleep in the last 24 hours. We had started at XA15 am in oak and flown to ont and phx then back to oak. At one point, just southeast of bishop, ca, we had both dozed off for a few moments. Also contributing were the high workload demands placed upon us by ATC. In retrospect, the best way to have avoided the whole mess would have been to call into scheduling 'fatigued.' however, the punitive attitude of our flight management prevents crew members from doing so out of fear of retribution. What is really needed here is a revamp of the far rest requirements and duty limits to consider the natural circadian rhythms of the human body.

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Original NASA ASRS Text

Title: CAPT OF AN AIRBUS A310 DSNDED BELOW ASSIGNED APCH ALT FOR AN ILS APCH DUE TO MISPROGRAMMING THE FMC.

Narrative: ON DSCNT INTO OAK WE WERE AT 8000 FT AND CLRED TO 5000 FT. PASSING 7200 FT WE WERE TOLD TO MAINTAIN 7000 FT. I DISENGAGED THE AUTOPLT AND LEVELED THE ACFT AT 7000 FT. I THEN RE-ENGAGED THE AUTOPLT. WE WERE THEN RECLRED TO 5000 FT, ASSIGNED A SPD OF 180 KTS AND ASKED TO EXPEDITE THE DSCNT. IN AN EFFORT TO GO DOWN AND SLOW DOWN WE FULLY CONFIGURED. WE WERE GIVEN A HEADING AND CLRED FOR THE ILS TO RWY 29, MAINTAIN 2500 FT UNTIL ESTABLISHED. I SET THE INTERCEPT HEADING IN THE HEADING SELECT WINDOW AND 2500 FT IN THE ALT SELECT WINDOW. SINCE WE WERE STILL QUITE A DISTANCE FROM THE FAP, APCHING 2500 FT WE RETURNED THE FLAPS TO 20 DEGS. AT LOC THE FO SET THE RWY HEADING IN THE HEADING SELECT WINDOW. AT SOME POINT IN TIME HE ALSO SET THE MISSED APCH ALT OF 4000 FT IN THE ALT SELECT WINDOW WHICH I WAS UNAWARE OF. THE AUTOPLT NEVER CAPTURED THE 2500 FT AND THE ACFT CONTINUED TO DSND TO 1900 FT BEFORE THE FO CALLED THE DEV TO MY ATTN. I RETURNED THE ACFT TO 2000 FT UNTIL THE GS WAS CAPTURED INSIDE OF ALVAR INTXN. THE STRANGE THING ABOUT THE INCIDENT IS THAT I DON'T HAVE ANY MEMORY OF DSNDING BELOW 2500 FT UNTIL THE FO SPOKE UP. I THINK THERE IS A POSSIBILITY THAT I FELL ASLEEP. AS TO WHAT LED UP TO THIS OCCURRENCE THERE ARE SEVERAL FACTORS. FIRST AND FOREMOST WAS FATIGUE ON THE PART OF MYSELF AND THE FO. DUE TO THE TRIP SCHEDULING WE BOTH HAD HAD ONLY 2 HRS SLEEP IN THE LAST 24 HRS. WE HAD STARTED AT XA15 AM IN OAK AND FLOWN TO ONT AND PHX THEN BACK TO OAK. AT ONE POINT, JUST SE OF BISHOP, CA, WE HAD BOTH DOZED OFF FOR A FEW MOMENTS. ALSO CONTRIBUTING WERE THE HIGH WORKLOAD DEMANDS PLACED UPON US BY ATC. IN RETROSPECT, THE BEST WAY TO HAVE AVOIDED THE WHOLE MESS WOULD HAVE BEEN TO CALL INTO SCHEDULING 'FATIGUED.' HOWEVER, THE PUNITIVE ATTITUDE OF OUR FLT MGMNT PREVENTS CREW MEMBERS FROM DOING SO OUT OF FEAR OF RETRIBUTION. WHAT IS REALLY NEEDED HERE IS A REVAMP OF THE FAR REST REQUIREMENTS AND DUTY LIMITS TO CONSIDER THE NATURAL CIRCADIAN RHYTHMS OF THE HUMAN BODY.

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.