Super King Air 200
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 60; Flight Crew Total 13500; Flight Crew Type 1800
Situational Awareness; Confusion
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
While descending on a LP GPS Approach; pilot not flying advised descent to 720 MSL to cross fix RUZAL. From the approach brief; this didn't sound correct. I asked the co-pilot to verify twice; and he responded '720 is correct'. At 900 MSL; Tower advised below glide path. We continued approach and landed uneventfully. The correct altitude at RUZAL is 1040 MSL.
When pilot flying asked for minimums pilot not flying responded with feet above ground rather than altimeter reading; causing pilot to descend to below minimum altitude. Mistake not noticed until tower called low altitude alert. At time ATIS reporting 1500 over visibility 7 miles.
BE200 flight crew describes the cause of a descent below minimums during a LP GPS approach. A low altitude alert is issued by the Tower.