The General Airways DC-3 was being used for a Civil Air Movement of military personnel from Boise to Lackland AFB via Pueblo. On the final leg of the flight icing weather conditions were encountered. The accretion of ice on the aircraft became critical and the flight crew attempted to reach Kerrville but ran out of fuel, crash-landed in trees and caught fire. PROBABLE CAUSE: “The captain’s poor judgement in continuing into known and dangerous icing conditions.”