According to a Federal Aviation Administration (FAA) inspector, the two private pilots reported that after departure, they proceeded to several airports for landings, before stopping at a fourth airport where they added air to the nose tire and took on 20.83 gallons of fuel. After a subsequent departure, the pilots flew the airplane south to two other airports, before turning north toward the original departure airport. About 15 miles south of the original departure airport, the engine began to run roughly, then finally quit. A witness stated that he observed the airplane just north of his position, with the engine not running, and heading east, when it made a right turn back towards his position and descended into a retention pond. The witness ran over to the pond and found that the two pilots had swum to shore. One of the pilots told the witness that they had "run out of fuel,” and a subsequent examination of the airplane by the FAA inspector after recovery from the pond found no fuel in the right tank and only 4 pints of fuel in the left tank.