Weather Briefing and Departure
Before departure, the pilot received a weather briefing from the Flight Service Station. The briefer advised of forecasted icing conditions along the intended route. The airplane was not equipped with any anti-icing or deicing systems.
Icing Encounter
About 15 minutes after departing, while at 14,000 feet MSL, ice began to form on the airplane. The pilot requested a lower altitude and a ground speed check. The airplane's ground speed was 170 knots. Twenty minutes later, the pilot again requested a lower altitude, but the controller was unable due to the minimum en route altitude (MEA).
Approximately 18 minutes after that, the pilot asked for another ground speed check. The controller responded with 150 knots. Eleven minutes later, the flight was cleared to 12,000 feet.
Continued Ice Accumulation
About 19 minutes after the clearance, the pilot reported that the airplane was picking up rime ice and again requested a lower altitude. About 7 minutes later, the controller reported a ground speed of 120 knots. Approximately 14 minutes after that, the pilot reported having problems maintaining airspeed and altitude.
Loss of Control
Six minutes later, the pilot reported that he was unable to maintain altitude. Radar contact was lost two minutes after that. The airplane subsequently collided with upsloping terrain in a wings-level, nose-down attitude.