On February 3, 1995, at 2007 hours Pacific standard time, a Schweizer 269C helicopter, N7509H, collided with the terrain about 10 miles south of Red Bluff Airport, Red Bluff, California. The pilots were conducting a combination visual flight rules (VFR) ferry and instructional flight to Modesto, California, and filed a VFR flight plan. The helicopter, operated by Precision Helicopters, Inc., Newberg, Oregon, sustained substantial damage. The certificated commercial pilot/certified flight instructor (CFI) received serious injuries; the dual student received minor injuries. Instrument meteorological conditions prevailed. The flight originated at Benton Field, Redding, California, at 1908 hours. National Transportation Safety Board investigators interviewed the pilot via a telephone on February 4, 1995, at 0815 hours. The pilot said that he was ferrying the helicopter to Los Angeles, California, and was also providing the passenger/student pilot dual instruction. He said that he continued the night flight because the student needed night flight instruction. The pilot was following automobiles on Interstate Highway 5, southbound, when he encountered extensive fog. He turned the helicopter 180 degrees toward the Red Bluff Airport and, between 2 and 3 minutes later, he lost all visual references. The helicopter subsequently collided with the terrain. He said the helicopter did not experience any preimpact mechanical malfunctions or failures. The pilot repeated his telephone statement in the aircraft accident report. He added, however, that the dual student was initially flying the helicopter after it departed Benton Field. The pilot said he assumed the controls when the visibility began to decrease. He also said that he lost all ground visual reference when he executed a descending 180-degree turn.