On May 5, 1996, at 1400 mountain daylight time, a Cessna A185E, N185MP, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, collided with trees during an aborted takeoff from a private airstrip located 31 miles east of Cascade, Idaho. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the airline transport pilot and his passenger were not injured. The intended destination for this flight was to Hailey, Idaho. The pilot reported that he had made a precautionary landing at the private grass airstrip due to weather. According to the pilot, after the weather improved, he executed a soft field takeoff but, after leveling off at 10 feet above ground level to increase airspeed, the aircraft would not accelerate above 60 miles per hour indicated airspeed. The pilot stated that he felt that there was now a tailwind. The aircraft's airspeed subsequently "dropped about 10 miles per hour" and, upon reaching the end of the runway, the aircraft collided with the tops of small trees before the pilot retarded the throttle and aborted the takeoff. The airplane landed approximately 300 feet off the end of the runway. The pilot reported that the grass strip was wet and soft with standing water at the north end.