Narrative:

First officer was flying. He briefed the approach. I added the restriction to be at or above the step down altitudes on the approach. Once cleared for the approach at 5000 ft. The first officer armed and captured the glide slope. Autopilot was engaged. As we approached carle fix I reminded him not to go below the 4000 ft. Restriction. He argued with me and kept the autopilot on. I commanded him to get the autopilot off and level off as we were now below 4000 ft and outside carle. We crossed carle at 3750 ft; 250 ft low. We debriefed the incident at the gate but the first officer told me I was wrong and that he could just follow the glide slope once cleared for the approach.

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Original NASA ASRS Text

Title: An Air Carrier Captain monitoring an ILS Runway 10 approach reminded the First Officer that step down altitudes were mandatory. The First Officer disagreed; left the autopilot engaged on the glideslope and was 250 FT low crossing CARLE.

Narrative: First Officer was flying. He briefed the approach. I added the restriction to be at or above the step down altitudes on the approach. Once cleared for the approach at 5000 FT. The First Officer armed and captured the glide slope. Autopilot was engaged. As we approached CARLE fix I reminded him not to go below the 4000 FT. restriction. He argued with me and kept the autopilot on. I commanded him to get the autopilot off and level off as we were now below 4000 FT and outside CARLE. We crossed CARLE at 3750 FT; 250 FT low. We debriefed the incident at the gate but the First Officer told me I was wrong and that he could just follow the glide slope once cleared for the approach.

Data retrieved from NASA's ASRS site as of April 2012 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.