NTSB Identification: SEA04FA083A
Accident occurred Sunday, May 16, 2004 in Tenino, WA
Probable Cause Approval Date: 09/13/2005
Aircraft: Cessna 170B, registration: N3510D
Injuries: 1 Fatal,1 Minor.

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.

At 2038:10, a Cessna 170B and a Cessna 210J collided in-flight about 5 miles southeast of Tenino, Washington, at 3,000 feet mean sea level (about 2,700 feet above ground level). The Cessna 170B, flown by a private pilot, sole occupant of the airplane, was transponder equipped squawking code 1200 and emitting Mode C altitude information. The Cessna 170B had just descended from 7,500 feet msl and was leveling off at 3,000 feet on a magnetic heading of 322 degrees when the collision occurred. The pilot of the Cessna 170B, whose engine was separated from the airplane as a result of the collision, was able to maintain control of the airplane and succeeded in making a forced landing to an open field. The pilot of the Cessna 210J, also the sole occupant, was not emitting a transponder code, and therefore no altitude or other identifying information was available. However, a radar target was observed to the left and on a collision course with the Cessna 170B, and is assumed to have been the Cessna 210J; there were no other aircraft observed in the immediate vicinity. At 2036:11, the aircraft were approximately 3 1/2 nautical miles apart, the Cessna 210J oriented on a heading of north, while the Cessna 170B was on a magnetic heading of 309 degrees. At 2036:34, both aircraft were still on their respective headings, however, their lateral separation had diminished by 3/4 of a mile; the airplanes were now 2 3/4 miles apart. At 2036:58, lateral separation was reduced by 1/2 mile to 2 1/4 miles, and at 2037:22 lateral separation was further reduced to 1 1/4 miles. At 0337:46, 24 seconds prior to the collision, radar data indicates the aircraft were separated by a lateral distance of approximately 3,300 feet. Based on scratch marks and paint transfer signatures observed on both aircraft, as well as an estimated speed of the overtaking Cessna 210J being 150 knots and the GPS readout speed of the Cessna 170B of 113 knots, calculations revealed a closure speed of 41 knots, and a collision angle of 8 degrees. A calculated convergence angle of 22 degrees was determined for the Cessna 210J and 150 degrees for the Cessna 170B. It was concluded that based on the Cessna 210J's convergence angle and pilot's unobstructed forward field of vision, the Cessna 210J pilot should have been able to detect the presence of the Cessna 170B using normal visual scanning procedures consistent with visual flight rule (VFR) operations.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The other pilot's failure to maintain an adequate visual lookout during cruise flight, which resulted in a midair collision between the two airplanes.

Full narrative available

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