The converted DC-4 cargo plane carried 3000 gallons of fuel to the Nixon Fork Gold Mine near McGrath, AK. This mine has a 4200 x 100 ft gravel runway (16/34). There is a hill at the south end of the runway which forces everyone to land to the south. The Carvair was coming in with a tail wind, attempting a landing on runway 16. The captain said that the airplane encountered sinking air and became low on the landing approach, and the right main landing gear struck the lip of the runway. The right main landing gear was torn off, which allowed the nose and right wing to collide with the runway surface. The right wing was torn off the fuselage, and caught fire. The airplane slid 180 degrees, went off the runway and ended up in a ditch. The right wing continued to burn for about 1.5 hours. The pilot indicated that the weather conditions consisted of an east wind of about 5 to 10 knots, and mostly clear skies, with isolated areas of convective cloud formations. PROBABLE CAUSE: “An undershoot and collision with the runway when the pilot misjudged the distance/altitude during the landing flare/touchdown.”