The landing area was described as having a brownout condition which caused the crash.
The operator of the crashed chopper involving Vice President Yemi Osinbajo in Kabba, Kogi, failed to carry out risk assessment test of the Kabba Stadium prior to the flight.
Akin Olateru, the Accident Investigation Bureau (AIB) Commissioner, made this known while presenting the bureau's report to newsmen in Lagos on Wednesday.
News Agency of Nigeria (NAN) reports that AIB released its preliminary report on the Feb. 2 Caverton Helicopter crash involving Vice President Yemi Osinbajo in Kabba, Kogi.
Olateru, presenting the reports exactly 11 days after Osinbajo and 11 others survived the crash, said: "The findings revealed that the helicopter had a valid Certificate of Air Worthiness. "But the operators, Caverton Helicopters Ltd., failed to carry out risk assessment test of the Kabba Stadium prior to the flight.
"Caverton Helicopters Ltd. did not conduct site survey of the landing field prior to this flight. "Caverton Helicopters Ltd. did not carry out safety and risk assessment of the landing area prior to dispatch of the flight.
"The helicopter hovered to land in a brownout condition." The AIB commissioner also attributed the crash landing of the Agusta Westland W139 Chopper, with registration number 5N-CML, to brownout, a condition generated by trying to land in a dusty and sandy environment.
Olateru said that the purpose of the preliminary investigation was to provide details of the initial facts, discussions and findings surrounding the occurrence.
He said that the investigation was conducted using information gathered from the witness statements, flight recorders, Health and Usage Monitoring System (HUMS) and Data, Flight Data Monitoring (FDM). The commissioner said that it also included preliminary inspection of the accident site and the wreckage.
He said drug and alcohol test for the crew could not be carried out, but they were properly licensed and adequately rested to operate the flight.
According to him, the Captain was the Pilot Flying (PF), and the Co-pilot was the Pilot Monitoring (PM) while the take-off, climb out, cruise and approach phases were normal.
Olateru said another helicopter operated by Nigeria Police Force (Bell 412; SN-PEJ) landed ahead of NGR002. He added that the crew briefed on landing in brownout and used the company's Brownout Landing Procedures.
"During the landing, at about 50 R to touchdown, a heavy brownout enveloped the helicopter and the crew lost visual contact with the ground.
"The Co-Pilot called out radio altimeter 35, 30, 25, 20, 15 and no more. "At about 14:34 hour (2.34pm), the helicopter touched down hard on the right main landing gear and rolled over to the right.
"The crew carried out Emergency Landing Procedures which included immediate engines shutdown, fuel shut OFF, battery switch OFF, and generators switch OFF," Olateru said.
Also he said that all occupants of the helicopter were evacuated uninjured, but the helicopter was substantially damaged. Olateru said the bureau had, as part of the safety recommendations, directed the Nigerian Civil Aviation Authority (NCAA) to issue an Advisory Circular to all helicopter operators flying in Nigeria to be alert of the possibility and the effect of brownout.
He said this was to ensure that appropriate procedures were put in place to mitigate its effect(s). The commissioner said the AIB also advised Caverton Helicopters Ltd.
to ensure that flight operations were carried out in accordance with the company's approved operations manual.
He said this include site survey and proper safety risk analysis are done before dispatching any helicopter to unapproved landing pads.
Meanwhile, reports had it that the management of Caverton helicopters said unusual weather condition caused the helicopter conveying Osinbajo to crash in Kogi state on Saturday, February 2.