On November 5, 1999, at 1745 central standard time, a Waco KNF biplane, N698N, was substantially damaged when it impacted trees and terrain during the final approach to the Promise Land Airpark Airport, Midway, Arkansas. The airplane was registered to and operated by the pilot. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 personal flight, and a flight plan was not filed. The local flight originated from the Promise Land Airpark Airport at 1730. According to the pilot, he maneuvered the airplane onto the final approach leg for runway 18, a 2,000 foot turf airstrip. He stated that the airplane was at 25 feet agl and overflying a road and trees, located north of the approach end of the runway, when he "felt a rapid sink of the aircraft." The pilot "applied full throttle and attempted to lower the nose of the aircraft, but within what seemed like a couple of seconds" the airplane's left wing contacted a tree. Subsequently, the airplane contacted the ground and came to rest upright. The pilot stated that he attributed the loss of altitude to "wind shear or [a] downdraft." A pilot, who executed an approach and full stop landing on runway 18 approximately 5 minutes prior to the accident airplane, reported that his airplane's airspeed "dropped suddenly from 60mph to 40mph," while crossing trees on final approach. He added that he attributed the loss of airspeed to "an unexpected tailwind or downdraft." The FAA inspector, who examined the airplane at the site, reported that the front wing spars for the upper and lower left wings were structurally damaged. The left elevator was bent, the left main landing gear assembly separated from the airframe, and the engine separated from the airframe.