Mr Graham confirmed that the two crew members and four passengers on board the aircraft were fatally injured and that there was a report of a fire outbreak when the helicopter crashed.
The National Transportation Safety Board (NTSB) has provided further details on the fatal helicopter crash that led to the death of the Group Chief Executive Officer of Access Holdings Plc, Herbert Wigwe, his wife, son and other crew members onboard.
The details were provided by a board member with the NTSB, Michael Graham, alongside the investigator in charge of the incident, Aaron Sours, at a press briefing on Saturday evening in Barstow, California.
Mr Graham confirmed that the two crew members and four passengers on board the aircraft were fatally injured and that there was a report of a fire outbreak when the helicopter crashed.
"As far as we know, from what was reported from witnesses that there was fire when the aircraft did contact the terrain," the official said.
He explained that they have a representative from the NTSB's Transportation Disaster Assistance division at the scene and that she is currently working with the family members of those who lost their lives.
The NTSB is an independent agency charged by the US Congress to investigate every civil aviation accident and significant accidents in the other modes of transportation across the United States of America.
On Saturday, PREMIUM TIMES reported the helicopter crash near the California-Nevada border. Apart from Mr Wigwe, his wife and his son, at least three other people are believed to have died in the crash.
Abimbola Ogunbanjo, former group chairman of Nigerian Exchange Group Plc (NGX Group), is also believed to be part of the passengers.
During the press briefing, the official said the ill-fated plane was rented from a chartered flight company based out of Burbank.
Asked about the weather conditions of the crash scene, Mr Graham said it was reported by witnesses that there was rain with some wintry mix.
"We currently have a meteorologist working on our team and we were working to analyse and get the exact weather conditions at that time. Of course, that's out in the middle of the desert so we'll have to find the closest reporting stations nearby to be able to give any accurate report," he said.
More details
Speaking further, Mr Graham said they are working at the incident scene to gather evidence.
"Our team methodically and systematically reviews all evidence and considers all potential factors to determine the probable cause," he said.
This, the official said, is the beginning of a long process and they will not jump to any conclusions, noting that a preliminary report will be available soon.
However, Mr Graham said, a full NTSB investigative report and investigation will last 12 to 24 months before a final report is published.
He explained that additional details about the accident included the crew which consisted of a pilot in command and a safety pilot. The NTSB said the accident flight was operated by Orbic Air LLC as a part 135 Charter flight.
The investigators said witness reports of the weather conditions at the time of the accident suggest rain and a wintry mix.
"The helicopter was not equipped with a cockpit voice recorder or a flight data recorder. This helicopter was not required to be equipped with those types of recording devices," he said.
Mr Graham said their investigators will be examining airworthiness to include maintenance and structures of the helicopter, operations, meteorology and air traffic control.
He listed parties to the ongoing investigation to include the FAA and Orbic Air LLC, adding that as the investigation continues, other parties could be named.
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The official disclosed that the French aviation accident investigation agency will serve as an accredited representative of the investigation because France is a state of the manufacturer of the Airbus helicopter and the Turbomeca engine.
"Both Airbus helicopters and Turbomeca engines will serve as technical advisors to the investigation," he noted.
He said the planned activities for the investigation will include travelling to the accident site to conduct the initial on-the-scene documentation, including aerial mapping of the wreckage with a drone and site measurements.
He urged eyewitnesses at the crash site to provide any further information they may have such as photos to support the bureau's investigation.
"We will provide support as well as investigative updates as they become available in the coming days," Mr Graham said.
