Video culled from three security camera recordings near the crash site shows the aircraft began rotating counterclockwise during takeoff Tuesday morning and rose slightly, nearly level, from a rooftop helipad, the agency said. The helicopter continued rotating counterclockwise for about 360 degrees before it pitched forward, nose low.
It "continued the counterclockwise rotation in a nose low attitude until it disappeared from the camera's field of view," the agency said in its one-page statement.
Available video apparently did not show the actual crash on a street next to the Space Needle, where the KOMO-TV chopper burst into flames, setting several vehicles ablaze and spewing burning fuel down the street.
Multiple witnesses reported seeing the helicopter lift off and begin a counterclockwise rotation, then pitch downward, still rotating, and crash. They indicated the fire began after the crash, the NTSB said.
Witnesses earlier told reporters they heard unusual noises coming from the aircraft as it lifted off from the helipad atop KOMO's six-story headquarters after refueling. The initial NTSB report did not discuss any noises.
The helicopter came to rest on its right side and "all major structural components" were located in the immediate area of the main wreckage, the NTSB said. Wreckage debris was found in a 340-foot radius of the main wreckage.
The initial report did not attempt to pinpoint a cause for the crash. A final report could take as long as a year, agency officials have said.
Agency investigators moved the wreckage to a secure hangar in Auburn, south of Seattle, where they are reconstructing the helicopter.
The wreck killed both men on board - pilot Gary Pfitzner, 59, and former KOMO photographer Bill Strothman, 62. The two worked for Helicopters Inc., of Cahokia, Ill., which owned the Eurocopter AS350 aircraft.
The agency continues combing through pilot and maintenance and company records associated with the flight, the NTSB's Dennis Hogenson said earlier. Investigators are focusing on the helicopter's engine, the airframe, the pilot and the environment.
A Seattle man in a car, Richard Newman, 38, was seriously burned when the helicopter crashed and caught fire. Newman underwent surgery Friday and afterward was reported back in intensive care in serious condition, a Harborview Medical Center spokeswoman said. He suffered burns covering nearly 20 percent of his body, on his back and arms.
The agency cautioned that the initial report was preliminary information and subject to change.