Weather Briefing and Flight Plan
The pilot obtained a weather briefing for an instrument flight rules (IFR) flight. The briefer informed the pilot of IFR conditions along the route and an airman's meteorological information (AIRMET) for icing conditions in the northern third of Colorado; however, the planned route was not within that AIRMET's boundaries. The pilot then filed an IFR flight plan.
Departure and Initial Climb
The flight departed and climbed to a cruising altitude of 9,000 feet. While in instrument meteorological conditions (IMC), the pilot observed that the airplane's groundspeed was lower than expected and that the outside air temperature was slightly below freezing. He contacted air traffic control (ATC), requested a descent to 7,000 feet, and initiated the descent.
Icing Encounter
Rime ice began to accumulate on the airplane's windshield, wings, and vertical stabilizer. The flight continued and was 25–30 miles past the nearest airport when the pilot advised ATC that the airplane could not maintain altitude due to icing. ATC recommended that the pilot reverse course and divert to that airport. The pilot then turned back toward the airport.
Descent and Visibility
The pilot stated that the airplane remained in a shallow descent, but he was able to maintain 80 mph airspeed. The flight broke out of the cloud layer at 4,500 feet. The pilot's outside view was obstructed by the ice-covered windshield, except for a 6-inch radius semi-circle that was cleared by the airplane's windshield defroster.
Terrain Impact
The flight continued toward the airport; however, it encountered rising terrain, and subsequently, the airplane impacted the ground.