The former Jackson resident and expert mountain pilot killed in a crash Tuesday near Helena, Mont., set out that afternoon to take photographs of a site where he was involved in a crash two years ago, his friends said Friday.

Officials with the National Transportation Safety Board arrived Friday to begin investigating the crash that killed Sparky Imeson, a Helena flight instructor. Imeson was born and raised in Jackson Hole and logged more than 20,000 hours flying airplanes. He and his parents founded Imeson Aviation Inc. in 1968 at Jackson Hole Airport.

Imeson, 64, took off alone from the Bozeman airport at 2:11 p.m. Tuesday. Searchers on Thursday found the wreckage of his Cessna 180 about two miles southwest of the Canyon Ferry airstrip.

Two friends, Gary McDonald and Galen Hanselman, said Imeson had intended to document the site of a 2007 crash in the Elkhorn Mountains in which he was a passenger.

Imeson gave regular presentations on mountain flying and backcountry survival techniques. His friends said he wanted to use the photos in those presentations.

On Sunday, Imeson apparently suffered oxygen depravation on a flight out of Helena.

Flight records from Flightaware.com indicate that during that trip Imeson climbed to an altitude of 24,000 feet, where the air is too thin for humans to survive without supplemental oxygen.

After becoming disoriented, he was talked down to a lower altitude by an air traffic controller in Salt Lake City, McDonald said. Imeson likely had oxygen but could have had a problem with his equipment, he said.

Altitude does not appear to have been a factor in Tuesday’s crash, said NTSB Deputy Regional Chief Debra Eckrote.

“A witness saw the aircraft flying low in the area,” Eckrote said. “It appears he cleared a ridge line and then collided with some trees.

Evidence on site indicates the aircraft hit a couple of trees and then the ground.”

The wreckage, which was spread “over a couple of hundred feet,” will be removed Saturday and taken to a hangar for inspection, Eckrote said.

Montana Aeronautics Division administrator Debbie Alke said Imeson climbed to 6,700 feet on Tuesday before he dropped off the radar.

McDonald speculated that with 40 years of flying experience, Imeson might have had engine trouble or run into some other unexpected problem.

“We know he was up there, he was going to take pictures. He had no trouble up on top in the high country, but he had trouble below,” McDonald said.