NTSB Identification: LAX01TA278.
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Accident occurred Sunday, August 12, 2001 in Alturas, CA
Probable Cause Approval Date: 05/28/2002
Aircraft: Douglas DC-3C, registration: N376AS
Injuries: 1 Serious,3 Uninjured.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.

The operator stated that their mission was to drop smoke jumpers on the Dusenbury fire incident in the South Warner Wilderness area of the Modoc National Forest. The air was smooth as the airplane descended over the fire. The 9 smoke jumpers were let out over the fire at 8,500 feet mean sea level (msl) in five passes, followed by four more passes to drop cargo. When the jump operations were completed, 360-degree circuits were made to gain altitude for the flight back to Redding. The "fasten seatbelt" sign was turned off for jump operations and cabin securing. There were two cabin crewmembers (spotters) on board who were securing the cabin for their return flight to Redding. As the airplane crossed over a ridge line at 9,000 feet msl (800 feet above ground level), it encountered a sudden wind shear, or downdraft, but then immediately back into smooth air. One spotter hit his helmet on the ceiling, but was not injured. The second spotter, who was in mid-cabin reported, "I just broke my leg." The pilot diverted the flight to Alturas. No other turbulence was encountered prior to or after the accident event. Following the accident, the pilot filed a "Safecon Aviation Safety Communique" through the U.S. Forest Service aviation management website. Additionally, the pilot made the following recommendations to prevent future accidents of this nature: 1) Re-emphasize to flight crews the importance of cabin safety awareness. 2) Re-emphasize to flight crews the potential for hidden turbulence over mountainous terrain. 3) Emphasize the importance of remaining in stable air while cabin personnel are securing cargo and moving about the cabin at the completion of drop missions. 4) Ensure all personnel aboard the aircraft are seated with seatbelts fastened whenever turbulence is anticipated.

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

The inadvertent encounter with terrain induced turbulence. A factor was the high terrain.

Full narrative available

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