Narrative:

On missed approach, assigned 3000 ft and heading for second approach to runway 27 back course. Altitude select on autoplt did not arm (reason unknown) and aircraft reached 3500 ft before I noticed it and returned to altitude. On second approach in, now deteriorating WX, I asked first officer for 2300 ft on altitude selector, which the first officer entered. I must have hit 'altitude select' before he entered it because it did not arm and I didn't notice it. At that point, I became concerned that we had not reset the FAF on the GPS and that we were inside the fix. Distraction by this discussion, I allowed the aircraft to descend through the 2300 ft minimum altitude to approximately 1800 ft before I determined our correct position on the approach. We were approximately 1.5 mi outside the fix, and the point at which we could descend to MDA of 1340 ft. I immediately disconnected the autoplt and initiated a missed approach. WX now below localizer runway 27 minimums. Diverted to det and landed safely after an ILS to minimums.

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Original NASA ASRS Text

Title: BEECH KING AIR 200 CAPT MADE THE SECOND MISSED APCH AFTER OVERSHOOTING ASSIGNED MISSED APCH ALT AND WANDERING BELOW APCH MINIMUMS OUTSIDE THE OM.

Narrative: ON MISSED APCH, ASSIGNED 3000 FT AND HEADING FOR SECOND APCH TO RWY 27 BACK COURSE. ALT SELECT ON AUTOPLT DID NOT ARM (REASON UNKNOWN) AND ACFT REACHED 3500 FT BEFORE I NOTICED IT AND RETURNED TO ALT. ON SECOND APCH IN, NOW DETERIORATING WX, I ASKED FO FOR 2300 FT ON ALT SELECTOR, WHICH THE FO ENTERED. I MUST HAVE HIT 'ALT SELECT' BEFORE HE ENTERED IT BECAUSE IT DID NOT ARM AND I DIDN'T NOTICE IT. AT THAT POINT, I BECAME CONCERNED THAT WE HAD NOT RESET THE FAF ON THE GPS AND THAT WE WERE INSIDE THE FIX. DISTR BY THIS DISCUSSION, I ALLOWED THE ACFT TO DSND THROUGH THE 2300 FT MINIMUM ALT TO APPROX 1800 FT BEFORE I DETERMINED OUR CORRECT POS ON THE APCH. WE WERE APPROX 1.5 MI OUTSIDE THE FIX, AND THE POINT AT WHICH WE COULD DSND TO MDA OF 1340 FT. I IMMEDIATELY DISCONNECTED THE AUTOPLT AND INITIATED A MISSED APCH. WX NOW BELOW LOC RWY 27 MINIMUMS. DIVERTED TO DET AND LANDED SAFELY AFTER AN ILS TO MINIMUMS.

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.