The National Transportation Safety Board report described the Feb. 10 accident that killed all three people aboard, but it drew no conclusions on what caused the Bell 206B JetRanger to go down on a remote film production ranch in the rugged Acton area of northern Los Angeles County.
The helicopter was being used for scenes in which an actor dropped a backpack to the ground from the hovering aircraft.
The production crew on the ground was not filming at the time, but there was a camera operator aboard and a GoPro camera pointed at an actor in the left front seat, the report said. The recording devices were sent to NTSB headquarters for examination.
"Dark night visual meteorological conditions prevailed," the report said.
The untitled, military-themed TV program was being produced by Eyeworks USA for Discovery Channel, the channel confirmed previously in a statement that said it was cooperating with authorities. The NTSB said Eyeworks contracted with Orbic Air, a helicopter services company, and the pilot filed paperwork with the Federal Aviation Administration under his own company, Crossbow Helicopters.
The report said the pilot and members of the production crew scouted the location a few weeks earlier and discussed maneuvers and what equipment they needed. Two scenes were necessary, with two
The helicopter left its base at Los Angeles' Van Nuys Airport, about 30 miles southwest of Acton, at 4:45 p.m. Feb. 9, with about 55 gallons of fuel aboard and 10 extra gallons in plastic containers, according to the report. After arriving at the shooting location, the pilot gave a safety briefing to production crew members and removed the fuel containers and left side doors.
The first flights began about 9 p.m. and lasted an hour as the pilot circled numerous times, returned to the landing zone to retrieve the backpack and discuss changes necessary for getting the right shot.
The production crew and the pilot took a meal break at 11 p.m. and the pilot took a 1 1/2- to two-hour sleep break in a trailer.
The second location was a plateau next to a valley, with the bag drop location illuminated by lights on two cranes. The NTSB said the pilot requested an additional smaller light to illuminate an area of sloping terrain and a line of glow sticks along a ridge leading to the drop zone.
The actor in the left front seat was illuminated by a flexible LED light pad, the report noted.
"Witnesses observed the helicopter depart normally and fly toward the plateau from the west," it said. "While maneuvering about 60 mph, the helicopter suddenly pitched down and collided with the terrain below the valley's wall. The production crew had expected the helicopter to perform high passes prior to maneuvering around near the plateau for the action shot and did not have the cameras on the ground set up or filming."
Debris was scattered for 170 feet.
The victims were identified earlier as pilot David Gene Gibbs, 59, of Valencia; cameraman Darren Arthur Rydstrom, 46, of Whittier; and Michael William Donatelli, 45, of Indiana, Pa.