On September 18, 1998, about 1130 Alaska daylight time, a tundra tire equipped Cessna 180 airplane, N9407C, sustained substantial damage during takeoff from a remote airstrip located about 17 miles southwest of Chalkitsik, Alaska. The airplane was being operated as a visual flight rules (VFR) personal flight under Title 14, CFR Part 91, when the accident occurred. The certificated private pilot, and the one passenger aboard, were not injured. Visual meteorological conditions prevailed, and a flight plan was filed. The flight originated at the accident airstrip, about 1125. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on September 22, the pilot reported that on the day of the accident he had already completed three round trips from the accident airstrip, ferrying passengers and supplies. He stated that during the accident takeoff run, about one-quarter down the runway, the airplane's main wheels sank into about 10 inches of soft mud. The airplane then nosed over, and sustained substantial damage to the wings, and rudder. The pilot noted that there were no preaccident anomalies with the airplane.