Narrative:

Weather had been VFR at ZZZ all day; with a ceiling about 3;500 and 8 miles of visibility; in rain. A low stratus layer at about 600 feet was south and southwest of ZZZ; across the bay. My company is single engine part 135; and must maintain glide to the shoreline. We have company routes and procedures in place to do this. I had gone to ZZZ1; on the far side of the bay from ZZZ. The far shoreline near ZZZ1 had a thin; scattered fog layer from 600 feet (MSL and AGL) to approximately 700 feet. It had been there all day; and had not really moved. It was a stable system. ZZZ1 is in class G airspace; and we had a company operational control release to operate in and out of ZZZ1. I was able to get under the fog layer before it started; and maintain glide distance to shore; stayed above minimum legal altitudes from terrain; and maintained legal cloud clearance and distance requirements. I spent approximately 15 minutes in ZZZ1 unloading freight; and I picked up one passenger to return to ZZZ. After takeoff; I stayed at the minimum legal altitude above terrain to make sure I had good cloud clearance. I had to stay right next to the shoreline to maintain glide distance to shore. There is one short over-water hop to make from the shoreline near ZZZ1 to an island at about 800 feet to maintain glide distance to shore. That area had been free of fog when I had gone to ZZZ1. However; now there was a fog layer at 500 feet. In that area. As I approached it; I thought I could see the layer breaking up and ending; because I could see far mountains through the fog. I decided that I could continue. When I thought the layer was ending; about half way to the island; I pulled up to maintain glide distance to shore. However; with the grey fog and the overcast sky above; I misjudged ; and ended up on instruments; going through the layer. The layer was about 100 feet thick; and I was in it for a few seconds. I was not in the vicinity of immediate rising terrain during the IMC encounter. Ultimately; I should have turned back around to ZZZ1. However; it was the last flight of the day; I was fatigued; daylight was about to fade quickly; and I did not want to get stuck in ZZZ1 overnight. In the future I will be on guard; especially near the end of the duty day; to not accept flights where there is a good chance I may not be able to return under good VFR conditions. Additionally; I recommend all VFR operators utilize tools such as synthetic vision for inadvertent IMC encounters. Our foreflight subscription gives us moving map; synthetic vision; with an attitude heading reference system (ahrs) overlay. These tools offer incredible situational awareness during an IMC encounter.

Related reports:

Google
 

Original NASA ASRS Text

Title: C206 pilot reported entering IMC while on a VFR flight plan.

Narrative: Weather had been VFR at ZZZ all day; with a ceiling about 3;500 and 8 miles of visibility; in rain. A low stratus layer at about 600 feet was S and SW of ZZZ; across the bay. My company is single engine Part 135; and must maintain glide to the shoreline. We have company routes and procedures in place to do this. I had gone to ZZZ1; on the far side of the bay from ZZZ. The far shoreline near ZZZ1 had a thin; scattered fog layer from 600 feet (MSL and AGL) to approximately 700 feet. It had been there all day; and had not really moved. It was a stable system. ZZZ1 is in class G airspace; and we had a company operational control release to operate in and out of ZZZ1. I was able to get under the fog layer before it started; and maintain glide distance to shore; stayed above minimum legal altitudes from terrain; and maintained legal cloud clearance and distance requirements. I spent approximately 15 minutes in ZZZ1 unloading freight; and I picked up one passenger to return to ZZZ. After takeoff; I stayed at the minimum legal altitude above terrain to make sure I had good cloud clearance. I had to stay right next to the shoreline to maintain glide distance to shore. There is one short over-water hop to make from the shoreline near ZZZ1 to an island at about 800 feet to maintain glide distance to shore. That area had been free of fog when I had gone to ZZZ1. However; now there was a fog layer at 500 feet. in that area. As I approached it; I thought I could see the layer breaking up and ending; because I could see far mountains through the fog. I decided that I could continue. When I thought the layer was ending; about half way to the island; I pulled up to maintain glide distance to shore. However; with the grey fog and the overcast sky above; I misjudged ; and ended up on instruments; going through the layer. The layer was about 100 feet thick; and I was in it for a few seconds. I was not in the vicinity of immediate rising terrain during the IMC encounter. Ultimately; I should have turned back around to ZZZ1. However; it was the last flight of the day; I was fatigued; daylight was about to fade quickly; and I did not want to get stuck in ZZZ1 overnight. In the future I will be on guard; especially near the end of the duty day; to not accept flights where there is a good chance I may not be able to return under good VFR conditions. Additionally; I recommend all VFR operators utilize tools such as synthetic vision for inadvertent IMC encounters. Our Foreflight subscription gives us moving map; synthetic vision; with an attitude heading reference system (AHRS) overlay. These tools offer incredible situational awareness during an IMC encounter.

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.