Narrative:

On 5/mon/89 I was serving as first officer from mem to las. The captain was flying, and I performed duties as PNF. From the arrival (crowe five I believe), we were directed to intercept the runway 25 ILS and track it inbound. The captain's VOR was on the ILS 25, and mine was left on the las VOR. The approach controller then cleared us for the approach, and the captain started to descend to FAF crossing altitude of 3800', since we were within 10 mi of the FAF. At 4100', the approach controller asked us to verify our altitude of 4100', since he was getting a low altitude alert on us. We were still outside the marker at this time, how far I'm not certain, but the glide slope needle was still full scale deflection at the top of the instrument. He then leveled off until glide slope interception, and completed the approach without further incident. Upon later investigation, the captain felt that he should have been crossing all intxns at the published approach altitudes, rather than going to FAF crossing altitude upon receipt of the clearance and being within 10 mi from FAF. This situation could be avoided with better crew coordination and following glide slope down on approach, using published intxns for altitude cross-checks.

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Original NASA ASRS Text

Title: ACR MLG DESCENDED BELOW MINIMUM CHARTED ALT STARTING AN ILS APCH INTO LAS AT NIGHT. MSAW ACTIVATED.

Narrative: ON 5/MON/89 I WAS SERVING AS F/O FROM MEM TO LAS. THE CAPT WAS FLYING, AND I PERFORMED DUTIES AS PNF. FROM THE ARRIVAL (CROWE FIVE I BELIEVE), WE WERE DIRECTED TO INTERCEPT THE RWY 25 ILS AND TRACK IT INBND. THE CAPT'S VOR WAS ON THE ILS 25, AND MINE WAS LEFT ON THE LAS VOR. THE APCH CTLR THEN CLRED US FOR THE APCH, AND THE CAPT STARTED TO DSND TO FAF XING ALT OF 3800', SINCE WE WERE WITHIN 10 MI OF THE FAF. AT 4100', THE APCH CTLR ASKED US TO VERIFY OUR ALT OF 4100', SINCE HE WAS GETTING A LOW ALT ALERT ON US. WE WERE STILL OUTSIDE THE MARKER AT THIS TIME, HOW FAR I'M NOT CERTAIN, BUT THE GLIDE SLOPE NEEDLE WAS STILL FULL SCALE DEFLECTION AT THE TOP OF THE INSTRUMENT. HE THEN LEVELED OFF UNTIL GLIDE SLOPE INTERCEPTION, AND COMPLETED THE APCH WITHOUT FURTHER INCIDENT. UPON LATER INVESTIGATION, THE CAPT FELT THAT HE SHOULD HAVE BEEN XING ALL INTXNS AT THE PUBLISHED APCH ALTS, RATHER THAN GOING TO FAF XING ALT UPON RECEIPT OF THE CLRNC AND BEING WITHIN 10 MI FROM FAF. THIS SITUATION COULD BE AVOIDED WITH BETTER CREW COORD AND FOLLOWING GLIDE SLOPE DOWN ON APCH, USING PUBLISHED INTXNS FOR ALT CROSS-CHECKS.

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.