Witnesses to a helicopter crash last month that killed three people told federal investigators that they heard an odd noise followed by a bang and then saw the helicopter descend without its rotor blades spinning.
A preliminary report by the National Transportation Safety board into the April 29 crash on Oahu also said witnesses saw that "the helicopter appeared to be descending vertically with little forward motion."
The report did not specify a cause for the crash of the helicopter on a residential street in Kailua, 15 miles (24 kilometers) northeast of Honolulu, The Honolulu Star-Advertiser reported Wednesday.
The accident killed 28-year-old pilot Joseph G. Berridge of Honolulu, and two female passengers, 28-year-old Ryan McAuliffe of Chicago, Illinois, and 76-year-old Jan Burgess of Australia.
A final report including a probable cause is likely to take 12 to 24 months to complete, said safety board spokesman Eric Weiss.
The helicopter was registered to United Helicopter Leasing LLC, and operated by Novictor Aviation LLC, which provides air tours under the business name of Novictor Helicopters, the report said.
The flight left Daniel K. Inouye International Airport in Honolulu at 8:54 a.m. in good weather operating by sight rather than instruments.
Democratic U.S. Sen. Mazie Hirono of Hawaii sent letters Tuesday to federal transportation officials requesting detailed information about helicopter accidents in the state.
State lawmakers have also called on federal officials to either ground all tour helicopters or ban flights over residential neighbors.