What happened
Prior to departure, the pilot received a weather briefing from a flight service station. During this briefing, the briefer noted that the weather included rime ice, mixed clouds, and various forms of precipitation, including mist, snow, sleet, and rain. The briefer specifically advised the pilot to expect icing, instrument flight rules (IFR) conditions, and turbulence along the route, noting that an anti-icing equipped aircraft would be necessary. The pilot did not identify an alternate airport during this briefing.
Shortly after takeoff, air traffic control identified the aircraft on radar as it climbed to 4,000 feet. The pilot initially reported accumulating very little ice and requested an increase in altitude to 6,000 feet. However, shortly after being cleared to the higher altitude, the pilot requested a descent to 3,000 feet because the aircraft would not climb. The controller subsequently cleared the aircraft to 3,200 feet, which was the minimum en route altitude for that area.
The pilot then requested to divert to a nearby airport and reported that the aircraft was accumulating a lot of ice, making it difficult to maintain altitude. During communications with air traffic control, the pilot indicated that the aircraft was losing altitude and that they could not find approach plates for the diversion airport. The pilot eventually stated they were unable to navigate an approach and would be descending. During the attempted forced landing, the aircraft impacted a tree and came to rest upright in a field approximately 4 miles southeast of the airport. There were no injuries reported.
The investigation
An examination of the aircraft revealed no anomalies with the airframe, engines, or systems. The pilot reported that there were no known issues with the deicing equipment prior to the event. The pilot also noted that visibility regarding the extent of ice accumulation was limited because the flight took place before sunrise.