The Accident Investigation Bureau (AIB) says the Caverton helicopter crash-landing incident involving Vice President Yemi Osinbajo was caused by a brownout.
Brownout is an in-flight visibility restriction caused by dust or sand in which the flight crew loses visual contact with nearby objects that provide the outside visual references and misjudge the distance from the air to the ground.
The Augusta Westland 139 helicopter 5N-CML involved in the crash is owned and operated by Caverton Helicopters Limited.
The crash landing happened in Kabba, Kogi state, on February 2, 2019, during the campaign season of the last presidential election.
In the report released on Tuesday, the AIB said the pilots did not have formal training on take-offs and landings in brownout conditions.
“The pilot and the co-pilot did not have formal training on flights in brownout conditions,” the report read.
“The flight crew encountered a brownout condition during the hover to land, which led to the loss of external visual references, spatial disorientation and loss of situational awareness resulting in a misjudgement of distance and ground clearance, as the flight crew tried to control the helicopter’s movements for landing.
“The helicopter landed hard and rolled over on its right side.
“The contributory factors were: inappropriate landing technique used, non-adherence to company procedures for known or anticipated brownout condition during landing and lack of risk assessment, limited landing site preparation and planning prior to commencement of the flight.”
All the 12 persons on board were uninjured and the AIB said the helicopter was destroyed.