Narrative:A Cessna 208B, N430A, was destroyed when it collided with terrain near Naches, Washington. The commercial pilot and nine passengers were killed.
The pilot was returning a group of skydivers to their home base after a weekend of skydiving. He flew several jump flights, and then stopped early in the afternoon to prepare the airplane for the flight home. The flight was planned into an area of clouds, turbulence, and icing, which the pilot had researched. He delayed the departure until he decided that he could complete the planned flight under visual flight rules (VFR). The flight departed Star (ID92), Idaho, about 1750 PDT, en route to Shelton (SHN), Washington. The accident occurred at night with little illumination of the moon, and the airplane was in an area of layered clouds. A detailed analysis of the weather conditions revealed that the flight probably encountered broken to overcast layers both below and above its flight altitude. The satellite and sounding images suggested that it was possibly in an area of mountain wave conditions, which can enhance icing. The recorded radar data indicated that the pilot was likely maneuvering to go around, above, or below rain showers or clouds while attempting to maintain VFR. The airplane likely entered clouds during the last 3 minutes of flight, and possibly icing and turbulence. It was turning when it departed from controlled flight, with the angle-of-attack increasing rapidly. The unpressurized airplane was flying at over 14,000 feet mean sea level for more than 1 hour during the flight. It reached 15,000 feet just prior to the accident in sequential 360-degree turns while climbing and descending. Supplemental oxygen was not being used. At these altitudes, the pilot would be substantially impaired by hypoxia, but would have virtually no subjective symptoms, and would likely be unaware of his impairment. The pilot had logged over 2,000 hours of total flight time, with nearly 300 hours in this make and model of airplane. He was instrument-rated, but had only logged a total of 2 hours of actual instrument flight time. Company policy was to fly under visual flight rules only, and they had not flight-checked the pilot for instrument flight.
Probable Cause:
PROBABLE CAUSE: "The pilot's failure to maintain an adequate airspeed to avoid an aerodynamic stall while maneuvering. Contributing to the accident were the pilot's impaired physiological state due to hypoxia, the pilot's inadequate preflight weather evaluation, and his attempted flight into areas of known adverse weather. Also contributing were the pilot's inadvertent flight into instrument meteorological conditions that included clouds, turbulence, and dark night conditions."
Accident investigation:
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Investigating agency: | NTSB |
Status: | Investigation completed |
Duration: | 1 year and 9 months | Accident number: | LAX08MA007 | Download report: | Summary report
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Classification:
Flightcrew incapacitation
Loss of control
Sources:
» Missing plane was carrying skydive group (KATU, 8-10-2007)
» FAA
» Wreckage of Missing Plane Found (Washington State DoT, 9-10-2007)
» NTSB
Photos
accident date:
07-10-2007type: Cessna 208B Grand Caravan
registration: N430A
accident date:
07-10-2007type: Cessna 208B Grand Caravan
registration: N430A
Composite radar ground trackt of Cessna 208 N430A
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does
not display the exact flight path.
Distance from Star-Snake River Skydiving Airport, ID to Shelton-Sanderson Field, WA as the crow flies is 642 km (401 miles).
Accident location: Exact; as reported in the official accident report.
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.