For the vast majority of Americans, helicopters are hardly a routine form of transportation. But a high-profile helicopter disaster — like the crash in Calabasas, Calif., that killed Kobe Bryant and eight other people on Sunday — can draw widespread attention to helicopter safety.

Helicopter rides are significantly riskier than commercial airline flights, but not as dangerous as a trip on a personal plane. And some trips — like personal or private helicopter rides — are far more likely than others to end in a fatal accident.

"I think it is natural to the public, whenever an accident happens, to start to question the overall safety of a certain type of flying," says Anthony Brickhouse, a professor of aerospace and occupational safety at Embry-Riddle Aeronautical University. "I would just caution people to be patient and to let the investigation play out so that we can figure out what happened."

Commercial plane travel is extremely safe, despite recent catastrophes like the Boeing 737 Max crashes; in many years the fatal accident rate in the U.S. is zero. Helicopters are more dangerous, according to data from the federal government, with a fatal accident rate of 0.72 per 100,000 flight hours in 2018.

But general aviation — like recreational flying — is even more dangerous than that, with a fatal accident rate of more than 1 accident per 100,000 flight hours in 2018.

In general, helicopters today are safer than they used to be: Over the past two decades, the fatal accident rate has dropped by half, according to the United States Helicopter Safety Team, or USHST, an alliance of government and industry representatives.

But the last few years have seen mixed results. The fatal accident rate rose in 2017 and 2018, before dropping slightly last year.

Some helicopter rides are far riskier than others. In the U.S., sightseeing tours, police and news helicopters and aerial observation flights tend to be safer than other flights, the USHST says. Corporate flights and "air taxi" flights are in the middle of the pack.

And personal or private helicopter flights are responsible for a disproportionate number of fatal helicopter accidents. Personal or private rides account for just 3% of flight hours, but more than a quarter of fatal accidents.

To make helicopter flights safer, the USHST urges changes in training and technology. It also urges pilots to avoid flying too low.

The group also highlights the risk of "get-there-itis," when pilots are so determined to arrive at a destination that they ignore signs of risk. In some cases a powerful passenger can also put pressure on a pilot to complete a trip in unsafe conditions, pilots say.

Bob Clifford, a lawyer who has worked in aviation litigation for decades, says helicopters offer little margin for error and when disasters do occur they are often catastrophic.

"When they work they're wonderful," Clifford says. "Incredible convenience, incredible experience. But the flaws, if there are any in flight, are very fatal."

But Brickhouse, the aerospace professor, says there are a number of ways that helicopter flights can go wrong without ending in disaster. In the event of an engine failure, for instance, a technique called autorotation can bring an aircraft down safely.

"It's not like you have an issue with the helicopter and because it's a helicopter, it's just going to fall out of the sky and everybody's going to perish," he says. "It's really not that simple."

There's another question that sometimes pops up after high-profile crashes: How does the risk of flying compare to the hazards of the road?

It's an oft-repeated fact that commercial air travel is much safer than driving. That's not necessarily the case for helicopters — but the crash rates for helicopters and cars are calculated differently, so it's hard to make a precise comparison.

But one thing is for sure: Americans spend far more time in their cars — some 70 billion hours a year, according to AAA — and as a result, are much more likely to die in a car crash than any other form of transportation.

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