A preliminary report by the National Transportation Safety Board released Thursday concluded that Uber's self-driving technology fitted a Volvo XC90 driving in Tempe, Arizona, spotted a woman 6 seconds before fatally striking her, but didn't automatically brake because that feature was disabled.
The report concluded that the driver, Rafaela Vasquez, didn't take control of the self-driving car until less than a second before impact and didn't begin braking until less than a second after the fatal crash with 49-year-old Elaine Herzberg on March 18.
Investigators concluded that Uber's array of sensors, cameras, and lidar equipment on the Volvo XC90 spotted Herzberg about 6 seconds before the impact, or more than 350 feet away from the car, which was traveling at 43 mph. The onboard computers didn't determine that Herzberg would be a threat to the Volvo's intended path until about 1.3 seconds before the crash, but didn't mitigate the car's speed or direction because those features were disabled. The systems did not alert Vasquez to take control either.
At roughly 40 mph, the Volvo would need more than 80 feet to brake to a stop. Volvo has said that its sensors can react in fractions of a second, up to 62 mph, and a human driver would need more than a second to react and brake.
According to investigators, Uber disabled automatic emergency braking when the car is in self-driving mode "to reduce the potential for erratic vehicle behavior." Previous reports have indicated that self-driving cars can brake or swerve erratically for bicyclists traveling in roadways or other small road hazards.
When the car is being driven by a human, the Uber XC90 test vehicle engages Volvo's standard automatic emergency braking systems.
The report outlines the night leading up to the crash and said that Vasquez, who can be seen in videos looking down away from the roadway, said she was not using her phone in the moments before the crash. Vasquez said that she had both her personal and work cellphones in the car, but neither had been used until calling 911 after the crash.
Vasquez left the Uber test facility at 9:14 p.m. for a test loop. At 9:39 p.m. Vasquez enabled the car's self-driving technology and ran for nearly 20 minutes before striking Herzberg at 9:58 p.m.
Vasquez said she monitored the self-driving car's information sensors seconds before the crash. Uber asks its test drivers to monitor diagnostic information from the self-driving sensors and tag areas of interest for later review.
Police reported that at the time of the crash, Vasquez didn't appear impaired. Uber settled a civil case with the victim's family shortly after the crash.
In a statement emailed to The Car Connection, Uber said it will cooperate with investigators.
“Over the course of the last two months, we’ve worked closely with the NTSB. As their investigation continues, we’ve initiated our own safety review of our self-driving vehicles program. We’ve also brought on former NTSB Chair Christopher Hart to advise us on our overall safety culture, and we look forward to sharing more on the changes we’ll make in the coming weeks,” an Uber official said in a statement.
In March, Arizona Governor Doug Ducey suspended Uber's permit to test self-driving cars in the state. Uber announced Wednesday that it would no longer test cars in Arizona.
This story has been updated with comment from Uber.