An autonomous Uber car spotted a pedestrian about six seconds before fatally hitting her but did not stop because the system used to automatically apply brakes in potentially dangerous situations had been disabled, US federal investigators said.
In a preliminary report on the crash, the National Transportation Safety Board (NTSB) said emergency braking manoeuvres are not enabled while Uber鈥檚 cars are under computer control 鈥渢o reduce the potential for erratic vehicle behaviour鈥�.
Instead, Uber relies on a human backup driver to intervene but the system is not designed to alert the driver.
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In the crash in March, the driver began steering less than a second before impact but did not brake until less than a second after impact, according to the preliminary report, which does not determine fault.
A video of the crash showed the driver looking down just before the vehicle struck and killed 49-year-old Elaine Herzberg in Tempe, Arizona. Uber said in a statement that it has worked closely with the NTSB and is doing an internal review of its self-driving vehicle programme.
The company has also brought in former NTSB chairman Christopher Hart 鈥渢o advise us on our overall safety culture, and we look forward to sharing more on the changes we鈥檒l make in the coming weeks鈥�.
The NTSB report comes a day after Uber pulled its self-driving cars out of Arizona, eliminating the jobs of about 300 people who served as backup drivers and performed other jobs connected to the vehicles.
Suspended
Uber had suspended testing of its self-driving vehicles in Arizona, Pittsburgh, San Francisco and Toronto while regulators investigated the cause of the March 18 crash.
Sensors on the fully autonomous Volvo XC-90 SUV spotted Ms Herzberg while the car was travelling at 43mph and determined that braking was needed 1.3 seconds before impact, according to the report.
The agency, which can make safety recommendations to other federal agencies, said information in the preliminary report can change as the investigation progresses and that no conclusions should be drawn from the report.
The NTSB preliminary report does not provide 鈥渁ny decisive findings or conclusions鈥�, said Daniel Scarpinato, spokesman for Arizona governor Doug Ducey.
鈥淲e await the more thorough and final investigative report. Uber鈥檚 self-driving vehicle suspension remains in place.鈥�
