Narrative:

We descended below an authority/authorized altitude after being cleared for the ILS 25 in oxnard with intersection altitude limitation. The problem arose #1 in transfer from instructions from approach to approach plate. We confused G/south intercept altitude with localizer 25 (X) FAF altitude. In doing so, we descended below 3300' to 2600', at which point we received a low altitude alert. #2 flight from lax to oxr was a flight of 17 mins, in which we experienced engine irregularities and were anticipating an emergency. As a result, the above occurred. Upon receiving an altitude alert, we climbed and intercepted the G/south. In situations where cockpit workload is heavy (17 min flight in complex airspace), complicated with a possible emergency dilemma, it's imperative to have good crew coordination and share the workload. Supplemental information from acn 128061: asked for G/south intercept altitude from first officer. He responded with the correct 3300' altitude. I asked him to confirm this and he then stated 'no, it is 2000'.' I began descent from 4000 to 2000' and was cautioned at 2300' by point mugu approach that aircraft was low. This aircraft is not equipped with approach plate holders and first officer's are not required to have charts. Due to this, my first officer was monitoring the approach with my commercial charts in his lap and incorrectly idented G/south intercept. My fault for not previewing approach visually myself. Fortunately, we had visibility contact with the ground at all times. Recommend that all export category aircraft have lit plate holders installed.

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Original NASA ASRS Text

Title: COMMUTER ACR DESCENDS TOO SOON ON ILS WHEN FO MISREADS APCH CHART FOR OXR, RESULTING IN MSAW.

Narrative: WE DSNDED BELOW AN AUTH ALT AFTER BEING CLRED FOR THE ILS 25 IN OXNARD WITH INTXN ALT LIMITATION. THE PROB AROSE #1 IN TRANSFER FROM INSTRUCTIONS FROM APCH TO APCH PLATE. WE CONFUSED G/S INTERCEPT ALT WITH LOC 25 (X) FAF ALT. IN DOING SO, WE DSNDED BELOW 3300' TO 2600', AT WHICH POINT WE RECEIVED A LOW ALT ALERT. #2 FLT FROM LAX TO OXR WAS A FLT OF 17 MINS, IN WHICH WE EXPERIENCED ENG IRREGULARITIES AND WERE ANTICIPATING AN EMER. AS A RESULT, THE ABOVE OCCURRED. UPON RECEIVING AN ALT ALERT, WE CLBED AND INTERCEPTED THE G/S. IN SITUATIONS WHERE COCKPIT WORKLOAD IS HEAVY (17 MIN FLT IN COMPLEX AIRSPACE), COMPLICATED WITH A POSSIBLE EMER DILEMMA, IT'S IMPERATIVE TO HAVE GOOD CREW COORD AND SHARE THE WORKLOAD. SUPPLEMENTAL INFO FROM ACN 128061: ASKED FOR G/S INTERCEPT ALT FROM F/O. HE RESPONDED WITH THE CORRECT 3300' ALT. I ASKED HIM TO CONFIRM THIS AND HE THEN STATED 'NO, IT IS 2000'.' I BEGAN DSCNT FROM 4000 TO 2000' AND WAS CAUTIONED AT 2300' BY POINT MUGU APCH THAT ACFT WAS LOW. THIS ACFT IS NOT EQUIPPED WITH APCH PLATE HOLDERS AND F/O'S ARE NOT REQUIRED TO HAVE CHARTS. DUE TO THIS, MY F/O WAS MONITORING THE APCH WITH MY COMMERCIAL CHARTS IN HIS LAP AND INCORRECTLY IDENTED G/S INTERCEPT. MY FAULT FOR NOT PREVIEWING APCH VISUALLY MYSELF. FORTUNATELY, WE HAD VIS CONTACT WITH THE GND AT ALL TIMES. RECOMMEND THAT ALL EXPORT CATEGORY ACFT HAVE LIT PLATE HOLDERS INSTALLED.

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.