Narrative:

On route to intercepting the localizer runway 19 on the approach the door opened unexpectedly. The resulting sound; wind and general turbulence caused me to descend below the glideslope and generate a low altitude alarm at the control facility.because the weather was at minimums and I was having trouble controlling the aircraft I elected to abort the approach and climb. ATC [gave] me instructions to higher altitudes which I had trouble maintaining due to the way the aircraft was performing with the door ajar and the fact that I was in IMC with turbulence.I was finally able to gain consistent control of the aircraft and ATC guided me to higher altitude outside of IMC and I was able (with ATC help) to get to [another airport] where I was able to land uneventfully. Throughout the entire process I had difficulty staying on altitude and being able to quickly reach assigned headings. At [the alternate airport] a 45 knot cross wind at altitude made it difficult to stay on the ILS; but I managed to stay within tolerances.I did not [request priority handling] because I felt I could handle the situation without doing that. I recognized the controllers had their hands full with the inclement weather and didn't want to further inconvenience them and other pilots.

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Original NASA ASRS Text

Title: The pilot of a BE58 experienced an unexpected opening of the cabin door on approach. A go-around and diversion was executed in instrument conditions with turbulence; where a successful landing was made.

Narrative: On route to intercepting the localizer Runway 19 on the approach the door opened unexpectedly. The resulting sound; wind and general turbulence caused me to descend below the glideslope and generate a low altitude alarm at the control facility.Because the weather was at minimums and I was having trouble controlling the aircraft I elected to abort the approach and climb. ATC [gave] me instructions to higher altitudes which I had trouble maintaining due to the way the aircraft was performing with the door ajar and the fact that I was in IMC with turbulence.I was finally able to gain consistent control of the aircraft and ATC guided me to higher altitude outside of IMC and I was able (with ATC help) to get to [another airport] where I was able to land uneventfully. Throughout the entire process I had difficulty staying on altitude and being able to quickly reach assigned headings. At [the alternate airport] a 45 knot cross wind at altitude made it difficult to stay on the ILS; but I managed to stay within tolerances.I did not [request priority handling] because I felt I could handle the situation without doing that. I recognized the controllers had their hands full with the inclement weather and didn't want to further inconvenience them and other pilots.

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.