Narrative:

Isn was reporting 1/4 mile vis and VV001 upon the time of my approach to runway 29. The city was in the clear and it looked like patchy fog around the area. After crossing the FAF I was able to see the runway and all approach and runway lights. Since isn can be a rather busy airport at times; it's normal practice for pilots to cancel IFR as soon as you can maintain VFR. I thought that this was a situation where the airport was just starting to clear up so I went back to center frequency to cancel my IFR flight plan. Being an instrument pilot with quite a bit of experience; I didn't think twice when I lost sight of the runway at around 500 feet AGL but had clear visual of both the approach lighting system and the runway threshold lights. I thought for sure that I would get the runway in sight shortly after that which prolonged my decision for a potential go around to avoid IMC conditions. I did eventually get the runway in sight but unfortunately temporarily flew into IMC conditions while on a VFR squawk code. I determined that a landing in IMC with runway in sight would be safer than going around in the IMC conditions so I continued to a landing. Lesson learned; don't be so quick to cancel IFR. That approach would have been legal if I stayed on my IFR clearance down to landing. I can honestly see how these types of scenarios could get an inexperienced VFR pilot into a world of trouble. The fog can be deceptive! This is the first time where I experienced a scenario like this.

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Original NASA ASRS Text

Title: SR22 pilot reported entering instrument conditions on approach after a premature cancellation of instrument flight plan.

Narrative: ISN was reporting 1/4 mile Vis and VV001 upon the time of my approach to Runway 29. The city was in the clear and it looked like patchy fog around the area. After crossing the FAF I was able to see the runway and all approach and runway lights. Since ISN can be a rather busy airport at times; it's normal practice for pilots to cancel IFR as soon as you can maintain VFR. I thought that this was a situation where the airport was just starting to clear up so I went back to center frequency to cancel my IFR flight plan. Being an Instrument pilot with quite a bit of experience; I didn't think twice when I lost sight of the runway at around 500 feet AGL but had clear visual of both the approach lighting system and the runway threshold lights. I thought for sure that I would get the runway in sight shortly after that which prolonged my decision for a potential go around to avoid IMC conditions. I did eventually get the runway in sight but unfortunately temporarily flew into IMC conditions while on a VFR squawk code. I determined that a landing in IMC with runway in sight would be safer than going around in the IMC conditions so I continued to a landing. Lesson learned; don't be so quick to cancel IFR. That approach would have been legal if I stayed on my IFR clearance down to landing. I can honestly see how these types of scenarios could get an inexperienced VFR pilot into a world of trouble. The fog can be deceptive! This is the first time where I experienced a scenario like this.

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.