The private pilot was attempting to land his airplane at night on the unlighted, unpaved private airstrip where he based the airplane. The airstrip was situated in a rural area, about 5 miles from the nearest town. The airstrip was oriented approximately east-west, atop a ridge that was oriented northeast-southwest. The ridge rose approximately 300 feet above the surrounding terrain. According to the pilot, during his final approach to the airstrip, he encountered a downdraft, and the airplane impacted the southwest side of the ridge. According to information provided by first responders, the airplane struck a tree and then terrain, and came to rest after a very short distance. The right wing was crushed and displaced aft, and the fuselage also sustained substantial damage. The pilot extracted himself from the wreckage, and utilized his mobile phone to summon assistance, since he was seriously injured. About 2 hours after the accident, he was airlifted to a hospital. Hospital medical personnel interviews and blood tests of the pilot conducted at least 3 hours after the accident revealed that the pilot appeared intoxicated, admitted to using methadone and morphine on a daily basis, and had a blood alcohol concentration of 0.246 grams/deciliter. FAA regulations prohibit operation of an aircraft by persons with blood alcohol concentrations of 0.040 grams/deciliter or greater. The pilot did not hold a valid FAA medical certificate. He also stated that he did not experience any mechanical deficiencies or failures of the airplane prior to the impact.