Los Angeles - Police, firefighters, news channels and tourists: helicopters are a constant buzz in the Los Angeles skies, but only a few wealthy people like Kobe Bryant could afford to use them on a daily basis.

The expensive, rapid option is restricted to a handful of businessmen and celebrities - including the late basketball legend - seeking to avoid the Californian city's notoriously clogged roads.

"Renting a machine like (Bryant's Sikorsky S-76) is about $4 000 an hour, the pilot is earning at least $100 000 a year," Philippe Lesourd, a helicopter pilot and instructor who has been flying in the state for 29 years, told AFP.

"It's not within anyone's reach."

Beside Bryant, other celebrities who regularly use helicopters include the Kardashian family, said Lesourd, as well as businessmen who prefer an option "about five or six times faster than the road with traffic."

Bryant started using private choppers around 2006.

After dropping his daughters at school by car in the morning, he would fly 40 miles north to the Lakers stadium in downtown LA for basketball training, and return to Newport Beach in time to collect them.

The journey took just 15 minutes by helicopter, compared to at least two hours by car during rush hour.

"I had to figure out a way where I could still train and focus on the craft but not compromise family time," Bryant once said.

After retiring in 2016, the basketball titan - worth an estimated $600 million - continued to rent helicopters and pilots for his travels.

He was in his regular helicopter Sunday morning when it crashed into a hillside near Los Angeles.

Eight others were killed, including his 13-year-old daughter, whom Kobe was accompanying to a basketball game she was due to play in.

'Unstable'

The causes of the disaster have not yet been determined, but the city was shrouded in a dense fog.

"He should have said to himself 'Let's take the car,' or stopped somewhere and waited a couple of hours for the fog to lift," said Lesourd.

According to Lesourd, the likeliest explanation is that the pilot suffered "spatial disorientation" after losing sight of the ground upon entering the clouds.

"A helicopter is unstable - not like a car or a plane. You constantly have to actively control its altitude," he said.

"When you're in the clouds, your brain doesn't know which way is up and which is down, like when you're scuba diving."

Bryant's pilot would have been highly experienced, because helicopters which transport individual passengers "on demand" require strict, airline-style permits to operate.

Such "air taxi" pilots - a minority of those flying helicopters - have to undergo regular training and drug testing checks, added Lesourd.

California is the US state with the highest number of helicopter accidents, with 177 recorded between 2007-2016, according to official statistics.

Helicopters were on average safer than airplanes in the US, with a fatality rate of 0.82 per 100 000 flying hours, including 55 deaths in 24 accidents last year.

But according to figures from a US helicopter safety group, private flights have the worst performance of any sector.

Over the past decade, they accounted for only three percent of flying hours, but 26 percent of fatal accidents.