NTSB Identification: SEA07TA181.
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Accident occurred Monday, June 25, 2007 in Tehachapi, CA
Probable Cause Approval Date: 08/28/2008
Aircraft: McDonnell Douglas DC 10-10, registration: N450AX
Injuries: 3 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.
The transport category airplane had been modified as a firefighting air tanker and was contracted to the State of California under an exclusive-use contract for the fire season. This was the second fire season for the operator, flight crew, and accident airplane. In order to facilitate the availability of the accident airplane, the contracting agency increased the personnel assigned to the program. Normal operational procedures required that a lead airplane fly the intended flight profile prior to the air tanker. The air tanker crew typically views the flight profile flown by the lead airplane, and then flies the profile while following the lead airplane. The lead airplane points out obstacles and general concerns along the flight path to the air tanker during that first flight. On the accident run, the original lead airplane with a pilot specifically trained for the DC-10 fire retardant drop procedures had switched out with a backup lead airplane and pilot in order to return to base for refueling purposes. The backup lead airplane flew the flight profile prior to the accident airplane joining the flight profile for the fire retardant drop. As the captain flew the profile, the accident airplane flew at a lower altitude than the lead airplane, entered a left turn, and impacted multiple trees with the left wing. The digital flight data recorder indicated that the airplane had entered a 35-degree left bank with a vertical acceleration from 0.8 to 1.4 G's, which is consistent with normal loading in a banked turn. Although the flight crew was experienced with the operation of the accident airplane, they had limited fire suppression experience. The operator provided training on the airplane and training in operating in the fire environment. The flight crew obtained the majority of their retardant drop experience (in excess of 100 hours using water for drops) during the certification testing for the airplane.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The captain's failure to maintain clearance from trees. Full narrative available
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