NBA star Kobe Bryant died alongside his daughter Gianna, 13 (Picture: AP/Reuters/Getty) Investigators say engine failure was not to blame for the helicopter crash which killed Kobe Bryant, his daughter and seven others. The five-time NBA champion, 41, died alongside his 13-year-old daughter Gianna on the way to a girls basketball tournament at his academy on January 26. The National Transportation Safety Board is looking into whether heavy fog could have led to the tragedy in Calabasas, near Los Angeles, California. Investigators say a cut tree branch at the site of the crash suggests the engine was working properly when the helicopter came crashing down. Very foggy conditions are thought to have contributed to the crash which killed nine people (Picture: AP) (Left to right) Natalia Diamante Bryant, Gianna Maria-Onore Bryant, Kobe Bryant, Bianka Bella Bryantand wife Vanessa Laine Bryant (Picture: @kobebryant) Officials carry bags of items away from the helicopter crash scene (Picture: Reuters) A passing mountain biker says he saw the helicopter slam into the ground and burst into a giant ball of flames. Advertisement Advertisement Conditions on the night were so foggy the LAPD grounded local police helicopters as a safety precaution. Recordings of the calls between pilot Ara Zobayan and air traffic control suggest he was trying to remain low beneath the fog, which some experts suggest could have led to him crashing into a mountain. Weather conditions and busy airspace on route meant the aircraft spent around 15 minutes circling shortly before the collision. ‘Experienced’ Zobayan received special clearance to fly through the fog and was said to be flying at 1,400 feet. The jerseys of late Los Angeles Laker Kobe Bryant (right) and of Gianna are draped on the seats at Staples Center before a Lakers’ NBA game against the Portland Trail Blazers (Picture: AP) Investigators have ruled out the possibility of engine failure (Picture: AP) A full report on the tragedy is not expected for at least a year (Picture: AP) Radar data revealed he then climbed to 2,300 feet before beginning a left descending turn. The wreckage of the Sikorsky S-76B was found at 1,085 feet, the NTSB said. In an audio clip air traffic controllers can be heard saying ‘You’re still too low level’ to the pilot. A full report by the NTSB is not expected until for at least a year, but its report today said the helicopter’s instrument panel and flight control were destroyed and most devices displaced. More: Kobe Bryant Woman cut ex-boyfriend's mother's head off with steak knives and left it in kitchen sink Kim Kardashian had a ‘surrogacy therapist’ to make sure she bonded with Chicago West Phillip Schofield defends Eamonn Holmes’ ‘hot tub’ joke amid coming out announcement Got a story for Metro.co.uk? Get in touch with our news team by emailing us at [email protected]. For more stories like this, check our news page. Advertisement Advertisement