On July 13, 1998, approximately 1815 Pacific daylight time, a Cessna 152, N24823, registered to Walla Walla College, and being operated/flown by a private pilot, sustained substantial damage during a controlled in-flight collision with terrain approximately 17 nautical miles east northeast of Milton-Freewater, Oregon. The pilot and passenger were uninjured. No flight plan had been filed and visual meteorological conditions prevailed. The flight, which was personal, was to have been operated under 14CFR91, and originated from the Walla Walla Regional airport, Walla Walla, Washington, approximately 1735. The pilot reported that while flying in the Tiger Canyon area southeast of Walla Walla, "I decided that the terrain around us are [sic] rising rather quickly so I started to climb. As I was climbing [the] airplane wasn't performing too well due to high density altitude. Since I was surrounded by valley a turn was not my option. I decided to fly straight without losing anymore airspeed, [and] I impacted [a] series of trees at [the] very top of the hill." The aircraft then impacted terrain. Meteorological conditions at the Walla Walla Regional airport, 20 nautical miles northwest of the accident site, at 1805 hours were as follows: Surface temperature: 84 degrees Fahrenheit Wind direction: 200 degrees magnetic Wind speed: 06 knots Altimeter: 29.89 inches of mercury Walla Walla elevation: 1,205 feet (MSL) The calculated density altitude at the Walla Walla Regional airport, under the above conditions was 3,186 feet. The estimated density altitude at the accident site (4,200 feet MSL), based on the above conditions, was 6,861 feet.