On September 15, 2010, about 1840 Alaska daylight time, a float-equipped Piper PA-18 airplane, N9699P, sustained substantial damage during takeoff-initial climb from a floatplane lake, when it collided midair with another float-equipped Piper PA-18 airplane, N2FD, which also sustained substantial damage. The accident occurred about 3 miles west of Dillingham, Alaska. The airplanes were being operated by the pilots as visual flight rules (VFR) personal local flights under the provisions of 14 Code of Federal Regulation Part 91. The solo commercial pilot of N9699P received serious injuries, and the solo private pilot of N2FD received minor injuries. Visual meteorological conditions prevailed, and no flight plans were filed.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 24, the pilot of N9699P said he and the pilot of N2FD were friends, and that they were both departing for the same destination. He said during a preflight inspection of his airplane he found the master switch on, and the battery was dead. He said he hand-propped the airplane, and taxied on the lake to warm up the engine. The pilot said when he applied power for takeoff, the other airplane was to his left and behind him. He said he was not able to use the airplane's radio due to the dead battery, and the alternator had not kicked in to start charging the battery. He said his intent was to climb straight out to the south from the lake, and then turn east toward their destination. He said as the airplane climbed toward the edge of the lake, he saw something that flashed by, and he heard a loud noise. He said he lost control of the airplane, and it impacted the ground next to the floatplane lake. He said the airplane received substantial damage to both wings and the fuselage.

During a telephone conversation with the NTSB IIC on October 1, the pilot of the other accident airplane, N2FD, said that he had made arrangements with the pilot of N9699P to meet at another location after departing their mutual home floatplane lake. He said he had started his airplane, and was taxiing on the lake. He contacted a nearby FAA flight service station via the airplane's radio, who advised of helicopter traffic in the area. He said he did not hear N9699P on the radio, and that the last time he saw N9699P, it was on the lake to his right, and he believed taxiing to warm up its engine. He said he applied takeoff power, believing that he was the first to leave, and was not aware that N9699P was also taking off. He said he heard a loud bang, and thought something had broken on his airplane causing a loss of control and the crash. The pilot said he did not know he had collided with another airplane until he exited the wreckage on the ground. He said the airplane received substantial damage to both wings and the fuselage.

On September 30, the IIC contacted a witness to the accident via telephone. The witness said he was in his residence adjacent to the floatplane lake, and heard two airplanes power up, one right after the other. He said it was unusual for two airplanes to takeoff at the same time, and he looked outside to watch. The witness said he was familiar with both airplanes and pilots, and that he did not know which airplane powered up first. He said both airplanes started to takeoff from different areas on the same side of the lake, and they were headed in the same direction. He said both airplanes lifted off the water and started to climb. He said N9699P was to the right of N2FD, and that N9699P appeared to be in a slight left bank. He said about 50-70 feet above the water, N9699P appeared to come up underneath N2FD's right wing. The witness said the airplanes collided, and tumbled to the shore of the lake.