On February 28, 1999, at 0806 mountain standard time, a Beech 35-C33 Debonair, N977MC, was substantially damaged following impact with terrain during initial climb after takeoff from Lake County Airport, Leadville, Colorado. The none-instrument rated private pilot and his two passengers were not injured. The airplane was being operated by the owner under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal cross-country flight which was originating at the time of the accident. No flight plan had been filed. According to a flight instructor/FAA accident prevention counselor, the pilot telephoned her several days prior to the accident and requested advice on flying into the airport (elevation 9,927 feet) with three passengers and baggage. She recommended that he not fly to the airport with a heavy load because of the reduction in an airplane's performance in high density altitude. The pilot reported that he had gotten some other advice about flying into the airport, and he decided to fly the trip. He arrived successfully. On the day of the accident, he purchased 24 gallons of fuel. He loaded two passengers and baggage for the return trip. He said that during the engine run up, he adjusted the engine's mixture for maximum power for that altitude. The pilot reported that he departed straight ahead and flew in ground effect for 1 to 2 miles before to turning south. He said that the airplane began to sink, and the airplane continued to sink as he approached a snow covered hill. He said that after the airplane impacted the hill, it slid 60 to 80 yards before impacting trees. The airplane came to rest approximately 1,500 feet northeast of the departure end of the runway. The pilot said that he believed he was in "some kind of down draft." He told the Investigator-In-Charge (IIC) that it "just didn't seem to have the power." The flight instructor observed the airplane departing on runway 34, and was anticipating for him to make a left crosswind departure because of rising terrain to the east. She suddenly heard an impact, and the airplane's engine was silent. She ran back to the FBO to report the accident. An accurate weight was not determined due to the unknown weight of the passengers and baggage. The pilot did estimate that the airplane's fuel tanks were half full. The maximum gross weight of the airplane was 3,050 pounds, and the empty weight as of March 25, 1981, was 1,943.5 pounds. Based on FAA medical records on the pilot and witness weight estimates on the two passengers and baggage, the airplane was estimated to weigh 2,950 pounds at takeoff. According to the airplane's Pilot's Operating Handbook & FAA approved Airplane Flight Manual, at 10,000 feet density altitude, the airplane was capable of climbing at 490 feet per minute at 90 knots indicated airspeed.