Narrative:

Scene call request with local EMS; day VFR. Evaluated weather prior to acceptance of the flight and determined the weather enroute to the planned receiving facility; 46 miles away; would be a 1000 ft to 1200 ft ceiling with 10 miles visibility and the weather in the vicinity of the destination would be 1500 ft with 10 miles visibility. This weather planning was based on ASOS stations along the route and local weather forecasts.departed the base and landed at the scene location 4 miles away. While waiting on the crew and patient; double checked the weather for any changes. None were noted; weather was holding as originally planned. Departed the scene location southeast bound on course for the receiving hospital. Enroute the ceiling was holding as predicted; however the visibility began to reduce slightly due to pockets of haze and mist. Deviated my route of flight to the west to avoid the pockets of haze. I kept the crew advised of the situation and told them that even though we had to make a slight change to the route due to decreasing visibility the weather was still looking good to continue. 20 miles from our destination; the ceiling and visibility dramatically decreased as I inadvertently entered into one of the pockets of haze and now fog. All of my initial options (land; divert; return) for the deteriorating weather procedure quickly were eliminated so I decided the safest option was IMC.I notified my crew of what I was doing as I began my climb; squawked 7700 and [advised ATC] to determine what my options were. I elected to execute the ILS into ZZZ. Just inside the final approach fix I broke out VFR; canceled IFR with tower and proceeded to the destination hospital uneventfully.take a closer look at evaluating the winter weather and how quickly it can change. Make the no -go decision sooner; be more conservative with weather particularly when flying a VFR only machine.

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Original NASA ASRS Text

Title: BHT-407 Captain reported entering IMC in a VFR only aircraft.

Narrative: Scene call request with local EMS; Day VFR. Evaluated weather prior to acceptance of the flight and determined the weather enroute to the planned receiving facility; 46 miles away; would be a 1000 ft to 1200 ft ceiling with 10 miles visibility and the weather in the vicinity of the destination would be 1500 ft with 10 miles visibility. This weather planning was based on ASOS stations along the route and local weather forecasts.Departed the base and landed at the scene location 4 miles away. While waiting on the crew and patient; double checked the weather for any changes. None were noted; weather was holding as originally planned. Departed the scene location southeast bound on course for the receiving hospital. Enroute the ceiling was holding as predicted; however the visibility began to reduce slightly due to pockets of haze and mist. Deviated my route of flight to the west to avoid the pockets of haze. I kept the crew advised of the situation and told them that even though we had to make a slight change to the route due to decreasing visibility the weather was still looking good to continue. 20 miles from our destination; the ceiling and visibility dramatically decreased as I inadvertently entered into one of the pockets of haze and now fog. All of my initial options (land; divert; return) for the deteriorating weather procedure quickly were eliminated so I decided the safest option was IMC.I notified my crew of what I was doing as I began my climb; squawked 7700 and [advised ATC] to determine what my options were. I elected to execute the ILS into ZZZ. Just inside the final approach fix I broke out VFR; canceled IFR with tower and proceeded to the destination hospital uneventfully.Take a closer look at evaluating the winter weather and how quickly it can change. Make the no -go decision sooner; be more conservative with weather particularly when flying a VFR only machine.

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.