The wing of a firefighting aircraft might have hit a tree and broken off before the tanker crashed into a canyon wall in Yosemite National Park, killing the pilot, federal investigators said Wednesday.
The twin-engine S-2T air tanker was destroyed when it hit the ground and caught fire, the National Transportation Safety Board said in a preliminary report on the Oct. 7 crash.
A more complete investigation is ongoing and expected to take months.
Veteran pilot Geoffrey “Craig” Hunt, the plane's sole crew member, was following another aircraft as he prepared to drop 1,200 gallons of chemical retardant on the fire that was climbing a steep canyon wall near the park's west entrance.
A third plane flew overhead, directing the firefighting efforts.
“The crew of the controller airplane reported that the accident airplane may have struck a tree with its wing, which separated from the airplane,” according the five-paragraph report. “Both aircrews reported that there was smoke in the area, but visibility was good.”
Authorities previously said the aircraft's left wing was found at the beginning of a roughly quarter-mile-long debris field.
Ken Pimlott, director of the California Department of Forestry and Fire Protection, said the agency hopes the final report will provide findings that can be used to minimize the inherent dangers of the job.
“We owe that to Craig, who traded his life in an effort to protect the lives of others,” Pimlott said in a statement.
The investigation was complicated because of the wildfire that eventually burned more than 300 acres, cutting off electricity and closing the main road into Yosemite Valley for days.
The state's remaining 22 air tankers were grounded for two days until investigators were satisfied that the crash was not a result of faulty equipment that could affect the rest of the fleet.
Hunt, 62, of San Jose was a 13-year veteran pilot of DynCorp International. Like the state's other air tanker pilots, he flew the plane under a contract with the state.
The air tankers form the backbone of the state's firefighting fleet, which also includes 11 helicopters and 14 observer planes used to guide the other firefighting aircraft.
Investigators previously said they had preliminarily ruled out problems caused by the age of the tanker fleet. The planes were manufactured as early as the 1950s for anti-submarine warfare but have been rebuilt repeatedly over the ensuing decades.