The helicopter that crashed in Southeast Alaska in late September, killing three people, entered a 500-foot freefall before dropping to a Glacier Bay National Park beach, according to a report released Friday by the National Transportation Safety Board.
The crash killed Anchorage business owner Josh Pepperd, 42, and his 11-year-old son Andrew, as well as Palmer air service owner David William King, 53, from Chickaloon.
Another of Pepperd's sons, 14-year-old Aiden, survived with serious injuries and talked with investigators about what happened.
Pepperd and Andrew remain missing. King's body was found three days after the crash about three-quarters of a mile from the crash site, near Lituya Bay.
Pepperd, owner of Davis Constructors and Engineers, had just bought the Airbus Helicopters AS350-B3e helicopter, and was flying it home from Texas.
Pepperd was sitting on the right side of the helicopter, piloting the craft. King sat in the left-hand seat as co-pilot with his own controls; he was along because of insurance policies requiring a pilot have a certain amount of flight time.
"We don't know if he was instructing. We don't know if they were doing flight training on the way up," said Clint Johnson, Alaska chief for the NTSB. "That's an unknown."
The helicopter left Juneau, flew over the mountains at 3,000 to 4,000 feet, then north along the coast.
The surviving teen told Alaska State Troopers that the pilot "reached down and rolled the throttle off" and left the collective up, NTSB investigator Joshua Lindberg wrote in the report.
The throttle controls engine speed. The collective, a lever next to the pilot's leg, controls the pitch angle of the rotor blades.
If the throttle is rolled back without decreasing the collective, the helicopter can lose rotor speed, according to a veteran Alaska helicopter pilot who asked not to be named. That, in turn, could lead to what happened next.
The helicopter entered a freefall from about 500 feet off the ground, the report states. The pilot increased the throttle again about 30 feet off the ground, but the teenager felt the helicopter hit the water and noticed it splashing in the cabin before he lost consciousness.
Investigators recovered an Appareo Vision 1000 unit, which was immersed in saltwater but should provide valuable information, Johnson said. The device is like a small flight-data recorder that takes images at a fast rate and records pitch, roll, acceleration, altitude changes and GPS coordinates.
The crash occurred about 60 miles northwest of Gustavus as the group flew from Juneau to Yakutat. The plan was to drop King off in Wasilla before heading to Anchorage.
Pepperd graduated from Wasilla High School in 1994, the same year he started his construction career as a union laborer, according to his obituary. He started full-time at Davis in 1999 and never left, founding sister company Mass Excavation Inc. Pepperd is survived by a large family including his four children and his wife, who is pregnant.
His memorial service was scheduled for Friday at Anchorage Bible Fellowship.
King started flying when he was 16 after graduating from Bettles High School, his obituary said. He flew solo cross-country to college in South Carolina and bought his first PA-20 at 17 with money made from Alaskan scene artwork.
King and his father founded Kingdom Air Corps, a missionary pilot and mechanic training program. He and his wife operated Last Frontier Aviation Group.
The preliminary NTSB report released Friday offers no official probable cause. That determination won't be made until next year at the earliest.