On May 29, 1998, about 1430 Alaska daylight time, a wheel equipped Cessna 185 airplane, N4761Q, sustained substantial damage while landing on a sand bar, located about 35 miles north of Kotzebue, Alaska. The airplane was being operated as a visual flight rules (VFR) local area government flight under Title 14, CFR Part 91, when the accident occurred. The airplane is registered to the State of Alaska, and operated by the Alaska State Troopers. The first pilot, seated in the right seat, and the second pilot, seated in the left seat, both certificated commercial pilots, received minor injuries. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated at the Kotzebue Airport, about 1300. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on June 2, the first pilot, a Fish and Wildlife Protection Officer for the State of Alaska, reported that he was providing flight instruction and recurrent training to the second pilot, a pilot for the Alaska State Troopers. He said that two successful landings were accomplished on the same sand bar prior to the accident. On the last approach to the south, and while the second pilot was manipulating the controls, the airplane encountered a downdraft, and landed in a river just short of the intended touchdown point. The airplane came to rest upside down in about 3 feet of water. Both pilots exited the airplane and waded to shore. The airplane sustained substantial damage to the wings, fuselage, and tail. Both pilots reported that the wind at the time of the accident was about 180 degrees at 10 knots.