20060423007092A

(-23) On the morning of 04/23/2006 (time unknown) a Cessna 172 piloted by privacy data omitted departed from the birchwood Alaska airport for a pleasure/shake down flight after completion of the aircrafts annual inspection. The pilot privacy data omitted did not file a flight plan. Approximately 11:30 am of the same day, a Cessna 170B piloted by privacy data omitted departed the same airport. The 170B pilot filed a flight plan, his plan showed him traveling from birchwood to talkeetna then return to birchwood, with a total flight time of 3 hours. The plan showed a total of 4 souls on board. The 3 occupants were children belonging to the pilot privacy data omitted. At approximately 11:53, the pilot of the 170 radioed flight service to modify his flight plan to 4 hours total time. Minutes after the radio call the 172 and the 170 collided in midair. The accident area was open and over marshy flats. The ground was frozen about 6 inches below the surface. I was unable to determine if any other aircraft were in the vicinity at the time of the accident. There were numerous witnesses available for interview. Some of the witnesses were on the ground in the general area bird watching. For the most part theseindividuals when interviewed did not see the actual collision but heard the sound and turned around to observe the aircraft mated together and then fall from the air. The 2 most informative witnesses were at a private home about 3/4 of a mile from the actual incident and observed the aircraft approach each other then collide and watched both fall to the ground. They had a clear view of the entire situation. These 2 individuals said they watched the 2 aircraft approaching each other and commented how close they were going to be when they passed. They stated that the 170 was heading in a northerly direction and the 172 was southwest bound. It appeared the 172 was at a lower altitide (approximately 50 or so feet). Both aircraft were between 1500 and 2000 feet AGL. They said the 172 passed under the 170 slightly and at one point one of the aircraft engines appeared to go to a higher RPM (by sound), at the same time the 172 made an abrupt pitch up maneuver. The witness who is a certificated pilot stated that the 172 looked almost as if it pitched into a stall type position. The 2 witnesses stated that the 172 wind screen made contact with the left outboard wing tip of the 170. The 2 aircraft then became tangled and hung in air for a moment. At some point the left wing of the 170 and the empennage and tail section of the 172 departed from their prospective aircraft. The aircraft then separated and fell to the ground. Light pieces of debris were seen by all witnesses fluttering to the ground which covered a large surface area at the scene. The large debris from both aircraft is listed in GPS coordinates on page 2. The aircraft as found at the scene showed high speed impact. The engines were both in deep depressions. There was no post crash fire. The witnesses called 911 and the approached the aircraft to assist any survivors. There were no survivors. I and the NTSB arrived at the scene. The state troopers were on site and had secured the area. We proceeded to document the scene and then allowed the troopers to extract the bodies. The aircraft were released to the insurance company for recovery that night. I the NTSB and a representative from Cessna reassembled the 2 aircraft as best as possible in a secure hangar. We were able to confirm for the most part the witness statements. The throttle position of the 170 was the only aircraft we were able to confirm, and it appeared to be in a cruise position. Due to the 170 radio call prior to the accident we confirmed from the additional owner that the radios were digital and had a single button frequency change. (Attempt here was to determine if the pilot of the 170 could have been changing radios at the time of the accident). It was found that the 170 propeller had slashed the left tire of the 172 and had torn the entire gear leg and wheel assembly from the aircraft. There were tire marks and green paint (170 colors) on the left side of the 172 empennage where this section had been torn from the aircraft. All color transfers were coordinated and confirmed all statements.