Radar data depicted the airplane flying northerly until about 1138, when it initiated a right turn to the south at about 400 feet msl. Witnesses then saw the airplane turn right to a westerly or northwesterly direction over land while radar depicted the airplane descending to about 200 feet msl. The airplane banked sharply left, and one witness observed the banner twist and separate. The airplane then banked to the right and impacted a 19-story condominium near its top floor. The airplane fell to the second floor deck and came to rest on its left side. Witnesses described the engine sound as either sputtering, operating normally or being at a low throttle setting.