Medical examiner said rugged terrain complicated efforts to recover remains of nine victims killed in Sunday crash outside LA

Investigators worked on a rugged hillside outside Los Angeles on Monday to determine the cause of the helicopter crash that killed retired basketball star Kobe Bryant, his daughter Gianna and seven others.

About 20 investigators scoured the crash site in Calabasas, 30 miles (48km) north-west of downtown Los Angeles, where the helicopter went down in foggy weather on Sunday.

The cause of the disaster remains unknown, and is under investigation by the National Transportation Safety Board. Federal safety investigators are exploring factors including the pilot’s history and the helicopter’s maintenance records, said NTSB member Jennifer Homendy.

But much attention has focused on the weather, which was considered dangerous enough that the Los Angeles police department and the county sheriff’s department had grounded their helicopters. Bryant’s helicopter had received special approval to fly in the worse-than-usual weather, the New York Times reported.

'Devastating': America mourns Kobe Bryant after death in helicopter crash Read more

The Sikorsky S-76 carrying Bryant and his fellow passengers took off from Santa Ana in Orange county, south of Los Angeles, shortly after 9am, heading north and then west. Authorities did not say where Bryant was going, but the helicopter appeared headed in the direction of his youth sports academy in nearby Thousand Oaks, which was holding a basketball tournament Sunday in which Bryant’s 13-year-old daughter, known as GiGi, was competing.

Play Video 2:04 Kobe Bryant, his daughter Gianna, and their shared love of basketball – video report

Air traffic controllers noted poor visibility around Burbank to the north and Van Nuys to the north-west. According to the New York Times, the helicopter circled near Burbank while awaiting clearance from air traffic controllers to keep going. It received clearance to proceed through Burbank’s airspace before it continued on to Calabasas, where it crashed into the hillside around 9.45am at about 1,400ft (426m), according to data from Flightradar24.

When it struck the ground, the helicopter was flying at about 160 knots (184mph) and descending at a rate of more than 4,000ft a minute, the data showed.

In his last radio message, the pilot, identified as Ara Zobayan, asked for air traffic controllers to provide “flight following” aid but was told the craft was too low, Homendy told reporters Monday afternoon.

About four minutes later, the pilot said he was climbing to avoid a cloud layer, she said. “When [air traffic control] asked what the pilot planned to do, there was no reply.”

Zobayan had asked for and received special clearance to fly in the heavy fog just minutes before the crash. Several aviation experts said it was not uncommon for pilots to be given this kind of approval, though some thought it unusual that it would be granted in a busy area like LA.

Kurt Deetz, a pilot who used to fly Bryant in the helicopter, said the crash was more likely caused by bad weather than by engine or other mechanical problems.

“The likelihood of a catastrophic twin engine failure on that aircraft, it just doesn’t happen,” he told the Los Angeles Times. He said the helicopter, which Bryant flew out of downtown LA when he retired from the NBA in 2016, was in “fantastic” condition, and that the owners of the chopper had a “very good maintenance program”. Deetz said the model was like “a Cadillac, a limousine”, one frequently used by celebrities.

Justin Green, an aviation attorney in New York who flew helicopters in the marine corps, said pilots can become disoriented in low visibility, losing track of which direction is up.

Green said a pilot flying an S-76 would be instrument-rated, meaning that person could fly the helicopter without relying on visual cues from outside.

“If you’re flying visually, if you get caught in a situation where you can’t see out the windshield, the life expectancy of the pilot and the aircraft is maybe 10, 15 seconds, and it happens all the time, and it’s really a shame,” added Randy Waldman, a helicopter flight instructor who teaches at the nearby Van Nuys airport.

Facebook Twitter Pinterest Investigators survey the wreckage of the helicopter crash that killed Kobe Bryant in Calabasas, California, 27 January 2020. Photograph: David Swanson/EPA

Colin Storm was in his living room in Calabasas when he heard what sounded to him like a low-flying airplane or helicopter.

“It was very foggy so we couldn’t see anything,” he said. “But then we heard some sputtering and then a boom.”

The fog cleared a bit, and Storm could see smoke rising from the hillside in front of his home.

Firefighters hiked in with medical equipment and hoses, and medical personnel rappelled to the site from a helicopter but found no survivors, authorities said.

The Los Angeles county medical examiner, Dr Jonathan Lucas, said the rugged terrain complicated efforts to recover the remains of the victims. He estimated it would take at least a couple of days to complete the task. Authorities initially recovered three bodies and said the search for other victims was ongoing along the Calabasas mountainside.

The local sheriff said on Monday fans and mourners had flooded the area around the crash site, with some people going into residential neighborhoods and attempting to get to the hillside where the investigation is ongoing. He said the resulting traffic was creating obstacles for emergency personnel.

The other victims in the crash included a well-known local college baseball coach, John Altobelli, and his wife and daughter, Keri and Alyssa. Friends and family members said Gianna’s basketball coach, Christina Mauser, and Ara Zobayan, the aircraft’s pilot, also died in the crash. Peyton Chester, a team-mate of Gianna, and her mother, Sarah, were also in the helicopter.

Bryant, 41, was one of the most famous athletes in America, and his death has led to an outpouring of tributes from celebrities, politicians and fans in his hometown.