On April 8, 2002, approximately 0945 Pacific daylight time, a WSK-PZL Mielec M-18A agricultural aircraft, N81705, registered to A-1 Aviation Inc. of Fairfield, Washington, and being flown by a commercial pilot, was substantially damaged when it impacted terrain during the takeoff from a private airstrip 6 miles southeast of Rockford, Washington. The pilot was seriously injured in the accident. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local 14 CFR 137 agricultural aerial application flight. In a written statement, the pilot reported that he had been operating from this airstrip for several days for the aerial application flights dispensing dry fertilizer on winter wheat in the local area. On the day of the accident, this was his fifth load of the day. The airstrip was described as a "one-way" strip landing to the south and taking off to the north. After loading the aircraft, the pilot taxied the aircraft to the south end and conducted his normal pre-takeoff cockpit checks. The pilot noted that the wind had started to change directions and was now blowing from the south at three to five mph. The takeoff roll was begun and the tail wheel started to lift off the surface. The pilot stated that everything was normal until the aircraft lifted off and he "knew that something was different and I didn't have enough lift." The aircraft flew approximately 100 yards and then settled to the ground. The propeller contacted the ground, the engine separated from the firewall and the aircraft nosed over. The pilot reported that the aircraft was loaded with 100 gallons of fuel (half tanks) and approximately the same amount of fertilizer that he had been using on previous flights. The pilot reported no mechanical failure or malfunction with the aircraft at the time of the accident. After the accident, witnesses indicated that there was a gust of wind that occurred at the end of the take-off run.