On April 8, 2025, about 1459 central daylight time, a Cassutt III M airplane, N5RR, was substantially damaged when it was involved in an accident near Haskell, Oklahoma. The pilot was fatally injured. The aircraft was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. A witness stated that he was standing in front of the accident pilot’s hangar and had observed the pilot complete two or three laps around the airport traffic pattern. On the final lap, he said the pilot flew the length of the runway at about 100 feet above the ground and then saw the airplane pitch nose up steeply off the end of the runway. The airplane climbed until the airplane slowed down, at which point the airplane leveled off and turned through crosswind to the downwind leg of the traffic pattern where it began to pick up speed once again. He stated that the pilot had routinely done this maneuver in the past. The witness stated that while the airplane was on the downwind leg of the traffic pattern, it entered an aileron roll, and while upside down, the nose dipped towards the ground and the airplane began to lose altitude. The airplane continued through the roll, and it looked like the pilot had managed to level the wings of the airplane and was in the process of pulling out of the ensuing shallow dive but didn’t have enough altitude to do so. The airplane impacted the ground at a shallow angle, bounced and tumbled with components separating from the airplane. According to the witness, it all happened in about 5 seconds and that it occurred very fast. The witness stated that he had never seen the pilot perform any aerobatic type maneuvers in the past. Multiple witnesses stated that the engine was running at full power at the time of the accident and heard no indication of an engine issue. The airplane was examined at the accident site, and all major components of the airplane were present. Control cable continuity was verified, and no flight control anomalies were noted. The engine exhibited impact damage and no anomalies were noted. Wood propeller blade fragments were found on and in the ground at the initial point of impact. The propeller hub remained attached to the propeller mounting flange. The pilot’s cellphone was recovered at the accident site, and a cursory examination of the phone provided flight track data from an application installed on the phone. No phone calls or texts were present at the time of the accident. The phone was retained for further examination.