On September 24, 2004, about 2000 Alaska daylight time, a float equipped de Havilland DHC-2 airplane, N1018D, sustained substantial damage when it collided with trees during landing at an off airport site located about 35 miles northeast of Willow, Alaska. The airplane was being operated as a visual flight rules (VFR) on-demand passenger flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated by Susitna Air Service, Inc., of Willow. The certificated commercial pilot and the two passengers were not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated at the Kashwitna Lake Seaplane Base, Willow, about 1940. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on September 25, the pilot said he was landing at a remote river slough, adjacent to the Kashwitna River. He said that after touchdown the left wing collided with a stand of trees. The airplane pivoted to the left, and the airplane's floats subsequently collided with the river bank. The airplane sustained structural damage to both wings and fuselage. The pilot noted that there were no preaccident mechanical anomalies with the airplane .