On April 11, 2003, about 1030 Pacific daylight time, a Cessna 177RG, N1925Q, collided with a parked and unoccupied Piper PA-23-250, N14002, while starting the engine at the Redding Municipal Airport (RDD), Redding, California. The airplane was register to and operated by Jim & I Aviators, Inc., of Redding, California, under the provisions of 14 CFR Part 91. The airline transport pilot, the sole occupant, was not injured; the airplane sustained substantial. The local instructional flight was originating at the time of the accident. Day visual meteorological conditions prevailed, and a flight plan had not been filed. In a written statement, the pilot reported that he was practicing flying from the right seat for his certified flight instructor certificate. During the engine start-up sequence, he inadvertently set the throttle position at 1/4-inch from full throttle, as opposed to the Cessna recommended setting of 1/4-inch from idle. He started the engine with insufficient pressure on the brake pedals to counteract the inadvertent throttle setting. The airplane rolled forward and began to veer to the right. The right wing of the Cessna passed over the left wing of a nearby, parked Piper and collided with the Piper's left propeller blade, which was vertically positioned,. After the pilot positioned the throttle to idle, the airplane came to a complete stop and he shut down the engine. The pilot stated that the Cessna sustained damage to the right wing's leading edge and right wing panels. The Piper incurred damage to the left propeller. The pilot reported no pre-impact mechanical malfunctions or failures with the airplane. During a telephone interview with the National Transportation Safety Board's investigator-in-charge (IIC), the operator of the Cessna stated that he visited the accident site. He reported that prior to the accident, the Cessna was parked on the left side of the Piper and about 10 feet behind it. He noted skid marks, which he thought were an indication that the pilot had been applying brakes during the collision.