NTSB Identification: ANC06FA048A
Accident occurred Sunday, April 23, 2006 in Chugiak, AK
Probable Cause Approval Date: 02/26/2007
Aircraft: Cessna 170B, registration: N4488B
Injuries: 5 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
Two airplanes, a Cessna 172, and a Cessna 170B, collided in mid air during cruise flight in day visual flight rules meteorological conditions. The 172, piloted by a solo commercial pilot, was traveling in a west-southwest direction. The 170B, with an airline transport certificated pilot and three passengers, was flying northbound, at an estimated altitude between 1,500 and 2,000 feet. A pilot-rated ground witness said he saw the two airplanes collide. He stated that as the Cessna 172 approached the Cessna 170B's right side, and as their flight paths converged, he heard the 172's engine power increase, and then saw the airplane pitch-up sharply. He said the two airplanes then collided, with the 170B striking the left side of the 172. Both airplanes became momentarily entwined, and then fell vertically to the ground. An examination of the wreckage disclosed impact signatures consistent with the witness's statement, with the 170B displaying black tire rubber deposits on portions of the white paint that covered the left lift strut. Traces of black, tire material were also discovered on portions of the 170B's propeller assembly. The Cessna 172's left main tire and inner tube were slashed longitudinally, consistent with a propeller strike, through to the aluminum wheel hub assembly. No radar coverage existed for the air space near the accident site, and neither pilot was in communication with any air traffic control facility. Toxicological samples were submitted from both pilots, and both tested negative for alcohol or drugs.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The inadequate visual lookout by the pilots of both airplanes during cruise flight, which resulted in their failure to see-and-avoid each other, and a subsequent midair collision. Full narrative available
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