On July 19, 1997, at 1730 Alaska daylight time, a Piper PA-18-150 airplane, N6822L, was destroyed when it departed the runway and struck trees at the owner's private airstrip located at mile 10, Knik-Goose Bay Road, 10 miles south of Wasilla, Alaska. The commercial certificated pilot and single passenger were not injured. The airplane was owned and operated under 14 CFR Part 91 by Garry T. Lynch of Wasilla, Alaska. Visual meteorological conditions prevailed at the time of the accident, with calm winds. The pilot, who was seated in the front seat, stated that he was conducting high speed taxi practice, with no intent for flight. He told the NTSB investigator that he gave control to his 18 year old son, who was in the back seat. The son caught his feet in the rudder pedals, the airplane became airborne, then departed the 1,000 foot long, 75 foot wide, gravel airstrip and impacted the trees. A witness who reported the accident to the Alaska State Troopers, stated that he saw the airplane impact trees at ten feet above the ground. A review of FAA records revealed that the pilot's medical certificate was expired. The last annual inspection conducted on the airplane was in 1988.