Narrative:

Extreme icing encounter emergency. I had been assigned a charter to fly from ZZZ-ZZZ1-ZZZ2-ZZZ early on the morning of [date]. I departed ZZZ without incident or concern; and shot the approach RNAV xx at ZZZ1. In the descent; I picked up some light rime [ice]; right on the leading edge; but nothing that was incredibly significant. I broke out about approximately 50 feet above minimums (350); in 8-9 miles visibility and landed without incident. After removing the ice; we taxied back for runway xy. As I was turning around and taking off I noticed that some mist moving towards the airport off the hills towards the south. During climb out on the odp everything began as normal; but quickly the plane decelerated from 105 knots to 90 knots; during climb out. Upon reaching 300 feet AGL; the plane was climbing at 100 feet/minute with significant ice buildup behind the protected area. I knew that at the current rate of ice accretion that we would never reach where the tops were (3;000 feet). Even though I could not [advise] ATC due to low altitude and poor radio reception; I had to [evaluate conditions] myself. Looking back; I could still make out the airport; and the hill beside it. And made a snap decision to turn back and land. We landed without incident.the only thing that I really have to say is that is absolutely the fastest I've ever seen ice accumulate. Only suggestion for myself is that if I see some sort of light mist hanging on the south side of a village like that again; and the temperatures are close to or at freezing; I may delay takeoff.

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Original NASA ASRS Text

Title: Cessna 208 pilot reported returning to departure airport after encountering icing conditions that severely affected aircraft performance.

Narrative: Extreme Icing Encounter Emergency. I had been assigned a charter to fly from ZZZ-ZZZ1-ZZZ2-ZZZ early on the morning of [date]. I departed ZZZ without incident or concern; and shot the approach RNAV XX at ZZZ1. In the descent; I picked up some light rime [ice]; right on the leading edge; but nothing that was incredibly significant. I broke out about approximately 50 feet above minimums (350); in 8-9 miles visibility and landed without incident. After removing the ice; we taxied back for Runway XY. As I was turning around and taking off I noticed that some mist moving towards the airport off the hills towards the south. During climb out on the ODP everything began as normal; but quickly the plane decelerated from 105 knots to 90 knots; during climb out. Upon reaching 300 feet AGL; the plane was climbing at 100 feet/minute with significant ice buildup behind the protected area. I knew that at the current rate of ice accretion that we would never reach where the tops were (3;000 feet). Even though I could not [advise] ATC due to low altitude and poor radio reception; I had to [evaluate conditions] myself. Looking back; I could still make out the airport; and the hill beside it. And made a snap decision to turn back and land. We landed without incident.The only thing that I really have to say is that is absolutely the fastest I've ever seen ice accumulate. Only suggestion for myself is that if I see some sort of light mist hanging on the south side of a village like that again; and the temperatures are close to or at freezing; I may delay takeoff.

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.