CALABASAS, California — The pilot of Kobe Bryant's ill-fated helicopter was flying too low to be monitored in fog, air traffic controller recordings showed on Monday (Jan 27), as coroner's investigators said they had recovered three bodies from the crash site and were searching for more remains.

The Sikorsky S-76 chopper slammed into a steep hillside outside the town of Calabasas, California, about 65km northwest of downtown Los Angeles, on Sunday, killing all nine people on board, igniting a brush fire and spreading debris over 1,000 sq m of grassy terrain.

The National Transportation Board is calling for the public to give it any photographs or video that might have been taken of the weather in the area of the helicopter wreck, which it said left a "devastating accident scene".

The NTSB offered no update on the search for victims but said investigators were expected to be on the scene for as many as five days.

The dense fog, and its role in the crash, came under scrutiny on Monday as fans, friends and family of the NBA superstar confronted the reality that the charismatic 41-year-old and his 13-year-old daughter, Gianna, were among those on board who died.

The Los Angeles County Coroner's Office said in a statement posted to its website that three bodies had been recovered from the debris field and taken to a forensic science centre for identification.

"Today, the search continues in the Calabasas mountainside for the other occupants in the fatal helicopter crash," the coroner's office said.

Bryant, who won five NBA championships in his 20 years with the Los Angeles Lakers, was known since his playing days to travel frequently by helicopter to avoid the Los Angeles area's glacial traffic.

LAKERS GAME CANCELLED

The NBA cancelled a game scheduled for Staples Center on Tuesday between the Lakers and their cross-town rivals the Clippers.

"The decision was made out of respect for the Lakers organisation, which is deeply grieving the tragic loss of Lakers legend Kobe Bryant, his daughter Gianna and seven other people in a helicopter crash on Sunday," the NBA said.

In addition to the Bryants, the crash devastated three other families linked to the Mamba Sports Academy on their way to a girls' basketball tournament: A husband and wife with their 13-year-old daughter; a mother and her 13-year-old daughter; and a basketball coach who was also a mum.

The ninth victim was the pilot, Ara Zobayan, an experienced former flight instructor who was instrument-rated, or qualified to fly in fog, according to multiple US media accounts.

Witnesses recounted thick fog over the foothills where the helicopter went down. The fog was so bad that both the Los Angeles Police Department and Los Angeles County Sheriff's Department grounded their helicopter fleets, the Los Angeles Times reported, citing officials.

Air traffic controllers gave the pilot "Special Visual Flight Rules", or clearance to fly in less than optimal weather around the Burbank airport.

A Federal Aviation Administration (FAA) official noted a pilot "does not get a general, or blanket, clearance from the FAA to fly in these conditions. A pilot is responsible for determining whether it is safe to fly in current and expected conditions".

Moreover, the pilot apparently requested "flight following," or constant tracking from controllers, but was informed he was flying too low to be picked up by air traffic control radar. It is unclear if the pilot heard the comment as it comes near the end of the doomed flight.

"Two echo x-ray, you're still too low level for flight following at this time," an air traffic controller told the pilot, according to publicly available audio of the conversation that was posted by several aviation websites.

The FAA and the National Transportation Safety Board are investigating the crash. A team of NTSB investigators were at the site on Monday going through the wreckage. It is expected to be on site for a few more days, NTSB spokesman Keith Holloway said.

'LOWER AND LOWER'

The radio traffic audio indicates the pilot tried to remain below clouds in order to remain in visual contact with the ground and avoid flying on instruments, said Mr Gary Robb, an aviation lawyer and author of the book Helicopter Crash Litigation.

Mr Robb said it was "certainly possible" that the pilot was "flying so low to get under the cloud cover that he clipped the top of that mountain that extended into the clouds".

"The dialogue between the pilot and air traffic control leads me to believe ... he kept wanting to go lower and lower, beneath the fog and ceiling, as we call it, and that could have led him to fly so low that he flew into the mountain," Mr Robb said.

The pilot, in his transmissions, "was calm and controlled the whole time", Mr Robb said, calling the communications "extremely normal and routine".

Investigators also would have to consider mechanical failure, Mr Robb said, though he described the Sikorsky twin-engine turbo helicopter as a "reliable" and "generally safe" aircraft.

The mourning continued a day after Bryant's death. After Lakers fans spontaneously built a shrine to Bryant near the Staples Center where he played his home games, fans laid down flowers and Bryant jerseys at Lower Merion High School outside Philadelphia, where Bryant played before joining the NBA.

In Hollywood, A-list stars including Robert De Niro and Brad Pitt took part in a moment of silence to honour Bryant at the start of the annual Academy Award nominees luncheon. Bryant, an Oscar winner for the animated short film Dear Basketball, attended the lunch two years ago.

In New York, early morning commuters emerging from Penn Station stopped for a silent moment before an enormous electronic billboard lit up with Bryant's image outside Madison Square Garden. REUTERS