NTSB Identification: LAX98FA086B
Accident occurred Wednesday, February 11, 1998 in MORGAN HILL, CA
Probable Cause Approval Date: 04/20/2000
Aircraft: Boeing CH-47D, registration: ARNG
Injuries: 1 Fatal,4 Uninjured.
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.
A flight of two military helicopters was on a northerly heading while N8343D was on a converging northwesterly heading at the same altitude. There were no indications that the occupants of either aircraft saw each other prior to colliding in midair. The crew of the second helicopter saw the airplane approaching, but did not have time to radio a warning. After the collision, the airplane entered an uncontrolled descent. The helicopter pilot made a precautionary, run-on landing, and made an emergency shutdown. The 5 feet 2 inch airplane pilot used a pillow, placed on the seat bottom to increase his seated height. The seat did not have a vertical adjustment. The sun was in the southwest quadrant, with scattered clouds and 20 miles visibility. The top and bottom rotating beacons, as well as landing lights of both helicopters were illuminated. The helicopter pilot was flight following, but had not received any conflicting traffic advisories. The airplane pilot was not communicating with ATC. The transponder in the airplane was squawking 1200 but the altitude was reported as erratic and unreliable. The unreliable altitude returns from the airplane disabled the automatic intruder program. The controller did not see the airplane as a primary target because he was busy handling other traffic.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot-in-command's failure to maintain visual separation from N8343D approaching from his right. The controller's failure to provide a traffic advisory and the copilot's and flight engineer's inadequate visual lookout were factors. Full narrative available
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