A Tesla Model S car steered by Autopilot crashed into a truck in May this year, killing its driver. The incident, officially the first fatal crash involving an autonomous car, has been described as a major setback for self-driving technology.
The US National Highway Traffic Safety Administration (NHTSA), investigating the incident, only revealed details on Thursday.
According to a blogpost on Tesla Motor’s website, the Model S crashed into a tractor trailer performing a left turn on a highway in Florida.
“Neither Autopilot nor the driver noticed the white side of the tractor trailer against a brightly lit sky, so the brake was not applied,” Tesla said. “The high ride height of the trailer combined with its positioning across the road and the extremely rare circumstances of the impact caused the Model S to pass under the trailer, with the bottom of the trailer impacting the windshield of the Model S.”
The electric vehicle manufacturer founded by SpaceX CEO Elon Musk stressed that the Autopilot feature is still in a testing phase and requires an explicit acknowledgement of this fact from the driver before being activated. However, the incident may heighten concerns about the safety of autonomous cars.
"We need more research into the interactions between driverless cars and driver-driven vehicles before we allow all drivers to take their hands off the wheel," AA president Edmund King commented on the incident. He said, however, that although not fool-proof, the driverless technology will enhance safety.
Neil Greig, director of policy and research at road safety charity IAM Roadsmart, said: "This tragic incident appears to be an early example of the problems caused by relying on driverless systems when very few vehicles have them.”
Tesla said its Autopilot function, launched last October, is only meant as an assistive feature and requires drivers to keep their hands on the wheel all the time.
“Every time that Autopilot is engaged, the car reminds the driver to ‘always keep your hands on the wheel. Be prepared to take over at any time’” Tesla wrote. “The system also makes frequent checks to ensure that the driver's hands remain on the wheel and provides visual and audible alerts if hands-on is not detected. It then gradually slows down the car until hands-on is detected again.”
The deceased driver, named as 40-year-old technology entrepreneur Joshua Brown from Canton, Ohio, was an avid Tesla fan.
He posted several videos on YouTube, praising the autopilot function, as well as pointing out its weaknesses. In a video from April this year, he described how the Autopilot prevented a side collision of his car with a boom truck.
"The truck tried to get to the exit ramp on the right and never saw my Tesla,” Brown wrote. “I actually wasn't watching that direction and Tessy (the name of my car) was on duty with Autopilot engaged. I became aware of the danger when Tessy alerted me with the ‘immediately take over’ warning chime and the car swerving to the right to avoid the side collision."
On the other hand, in a video from last October, Brown described several situations, in which the driver needs to be aware of the Autopilot’s quirks.
However, 62 years old Frank Baressi who drove the tractor trailer, which ultimately killed Mr Brown, indicated the Tesla enthusiast may have been over-relying on his car's self-driving abilities.
According to Baressi's account, Brown was driving so fast he didn’t even see him going through the trailer. He also claimed the deceased was watching Harry Potter on the car's TV screen.
"It was still playing when he died and snapped a telephone pole a quarter mile down the road.”
Tesla said the fatality, the first one involving an Autopilot-driven Tesla, came after 130 million miles driven with the functionality engaged. “Among all vehicles in the US, there is a fatality every 94 million miles,” the car-maker said. “Worldwide, there is a fatality approximately every 60 million miles.”
The NHTSA is now investigating the 25,000 Tesla Model S sedans equipped with the Autopilot system.
The NHTSA said the crash "calls for an examination of the design and performance of any driving aids in use at the time of the crash." The agency said it has opened a preliminary investigation that is the first step before it could seek to order a recall if it finds the vehicles were unsafe.
The Autopilot functionality has been criticised by many for being launched to early. Multiple videos have emerged since showing drivers tightly escaping collisions while relying on Autopilot.
In January, Tesla updated the Autopilot driving systems in Model S sedans to put new limits on its hands-free operation. The function was restricted on residential roads or roads without a centre divider.
"Autopilot is getting better all the time, but it is not perfect and still requires the driver to remain alert,” Tesla said on Thursday. “Nonetheless, when used in conjunction with driver oversight, the data is unequivocal that Autopilot reduces driver workload and results in a statistically significant improvement in safety when compared to purely manual driving."
Tesla shares fell as much as 3 per cent, or $6.28, in after-hours trading, on the news of the fatal crash and the investigation.
The following video was reportedly posted by the deceased driver about a month before his death. It shows how his Autopilot-supported Tesla helped him escape a collision with a boom truck.