The pilot of the helicopter which crashed killing basketball superstar Kobe Bryant, his young daughter, and seven other people had probably become disorientated amid fog, US safety investigators have said.
The helicopter smashed into a hillside near Calabasas, California, on 26 January 2020.
Pilot Ara Zobayan was among the dead.
Investigators also said Zobayan may have felt “self-induced pressure” to complete the flight for Bryant.
The US National Transportation Safety Board (NTSB) has been investigating the circumstances around the crash, and met on Tuesday to vote on the probable cause. It is an independent federal agency with no enforcement powers.
In its official finding, the NTSB said the main cause of the crash was most likely the pilot’s decision to keep flying in inclement conditions, “which resulted in the pilot’s spatial disorientation and loss of control”.
During the flight, Zobayan told air traffic controllers the helicopter was climbing out of heavy cloud when it was actually descending.
“This manoeuvre is consistent with the pilot experiencing spatial disorientation in limited visibility conditions,” said NTSB chairman Robert Sumwalt.
“We are talking about spatial disorientation where literally the pilot may not know which way is up or down, whether he or she is leaning left or right.”
The NTSB added that “inadequate review and oversight” of safety management processes by the helicopter charter company, Island Express, may have also contributed to the crash.
However, the board did not find that the Sikorsky S-76B had experienced any mechanical problems. The helicopter was not required to have “black box” recorders, which capture flight data and voices in the cockpit, and was not carrying any.
Zobayan violated federal rules and went against his own flight training by flying into thick clouds, safety officials said.
The pilot “was flying under visual flight orders or VFR which legally prohibited him from penetrating the clouds”, but he did so anyway, said Mr Sumwalt.
Investigators also criticised Zobayan for banking the helicopter to the left, instead of bringing the aircraft straight up while trying to escape the bad weather.
Zobayan was an experienced pilot who had often flown for Bryant. The widely respected pilot had logged more than 1,200 hours in the Sikorsky-76 helicopter.
Disorientation can set in when pilots can’t see the sky or landscape, making it harder to judge an aircraft’s altitude and acceleration.
Investigators also said that the close relationship between Bryant and Zobayan may have compelled the pilot to fly even in unsafe conditions.
In text messages on the eve of the crash released by the NTSB, Zobayan wrote that the forecast seemed to be “not the best”. The next morning, he wrote that the conditions were “looking ok”.
At the time of the crash, retired NBA legend Bryant, 41, was travelling to a youth basketball tournament with his 13-year-old daughter, Gianna, two of her teammates, and several other friends.
The fatal crash prompted a global outpouring of support for the NBA star and his family – as well as a number of lawsuits.
Bryant’s wife, Vanessa Bryant, sued Zobayan and the companies that owned and operated the helicopter for alleged negligence and wrongful death. Families of the other victims sued the helicopter companies – but not Zobayan.
In September, Ms Bryant sued the Los Angeles County Sheriff’s Department after officers shared unauthorised photos of the crash site. California now has a state law prohibiting first responders from taking unauthorised pictures of people who died at the scene of an accident or crime.