Narrative:

The problem was inadequate preparation for an ILS approach into our alternate airport. I filed for the RNAV runway 2 approach into [our destination airport]. ASOS reported 200 feet; mist; minimums were 456. We attempted a coupled approach anyway. Early in the approach the autopilot decoupled at about 1000 ft and I went missed approach. I attempted another approach down to minimums without the autopilot and again went missed. I was a little rattled after that approach. Gave up on [this airport] and requested an approach into my alternate; and I was cleared immediately to [the initial approach fix] intersection for the 30L ILS. Well; [the alternate] is only 5 minutes away; and I had not loaded a flight plan; nor the approach - let alone prepped for the approach. When I attempted to fly a heading to [the initial approach fix]; the autopilot would not hold altitude - it was suffering from some kind of intermittent run-away trim. I had difficulty multi-tasking; flying the plane; trouble-shooting the autopilot; loading the approach and communicating with ATC. We failed to properly maintain altitude and vectors for a period of time - busting the 5100 ft assigned altitude by over 300 ft several times. I finally got the approach loaded; gave up on fixing the autopilot and shot the approach. However; my descent was well above the GS. I landed uneventfully.the next day I discovered that the autopilot steering knob was off center. We were unable to see that miss-setting the previous night due to night conditions. After resetting the steering knob to center the autopilot performed properly.the lesson learned is to have the alternate airport flight plan already programmed and prepped before attempting a primary approach where the conditions are reported near minimums.I never should have accepted ATC's initial clearance before having loaded and prepped for the approach. I should have requested to fly a course away from the action (out to sea) to give me time to get my wits about me from the previous two missed approaches; diagnose the autopilot; program the course; load and prep for the approach; and then finally request a clearance to [the alternate airport].the approach controller was so frustrated with my lack of precision in following his vectors that he asked: 'are you instrument rated?'. I told him: 'I was until tonight!' I should have informed the controller of my lack of preparation for the approach and multitasking problems created by the misbehaving autopilot. Had I informed him; perhaps he would have vectored me off somewhere safe to get my act together and only then clear me for the approach.

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Original NASA ASRS Text

Title: A C425 Pilot attempted two RNAV approaches to his destination but below minimum weather forced missed approach on each. Clearance to his alternate began direct an approach waypoint which was not programmed. The Pilot was overloaded multitasking with an apparent runway trim but landed safety. He discovered his autopilot steering knob was off center.

Narrative: The problem was inadequate preparation for an ILS approach into our alternate airport. I filed for the RNAV RWY 2 approach into [our destination airport]. ASOS reported 200 feet; mist; minimums were 456. We attempted a coupled approach anyway. Early in the approach the autopilot decoupled at about 1000 ft and I went missed approach. I attempted another approach down to minimums without the autopilot and again went missed. I was a little rattled after that approach. Gave up on [this airport] and requested an approach into my alternate; and I was cleared immediately to [the initial approach fix] intersection for the 30L ILS. Well; [the alternate] is only 5 minutes away; and I had not loaded a flight plan; nor the approach - let alone prepped for the approach. When I attempted to fly a heading to [the initial approach fix]; the autopilot would not hold altitude - it was suffering from some kind of intermittent run-away trim. I had difficulty multi-tasking; flying the plane; trouble-shooting the autopilot; loading the approach and communicating with ATC. We failed to properly maintain altitude and vectors for a period of time - busting the 5100 ft assigned altitude by over 300 ft several times. I finally got the approach loaded; gave up on fixing the autopilot and shot the approach. However; my descent was well above the GS. I landed uneventfully.The next day I discovered that the autopilot steering knob was off center. We were unable to see that miss-setting the previous night due to night conditions. After resetting the steering knob to center the autopilot performed properly.The lesson learned is to have the alternate airport flight plan already programmed and prepped before attempting a primary approach where the conditions are reported near minimums.I never should have accepted ATC's initial clearance before having loaded and prepped for the approach. I should have requested to fly a course away from the action (out to sea) to give me time to get my wits about me from the previous two missed approaches; diagnose the autopilot; program the course; load and prep for the approach; and then finally request a clearance to [the alternate airport].The approach controller was so frustrated with my lack of precision in following his vectors that he asked: 'Are you instrument rated?'. I told him: 'I was until tonight!' I should have informed the controller of my lack of preparation for the approach and multitasking problems created by the misbehaving autopilot. Had I informed him; perhaps he would have vectored me off somewhere safe to get my act together and only then clear me for the approach.

Data retrieved from NASA's ASRS site 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.