DETROIT (AP) — A government investigation has found that a design flaw in Tesla's Autopilot semi-autonomous driving system and driver inattention combined to cause a Model S electric car to slam into a firetruck parked along a California freeway.
The National Transportation Safety Board determined that the driver was overly reliant on the system and that Autopilot's design let him disengage from driving.
The agency released a brief report Wednesday that outlined the probable cause of the January 2018 crash on a highway in Culver City.
The findings raise questions about the effectiveness of the Autopilot system, which was engaged but failed to take action in the Culver City crash and three others in which drivers were killed since 2016.
The driver in the Jan. 22, 2018 firetruck crash on Interstate 405 was not hurt. But the NTSB report says he did not have his hands on the steering wheel at the time of the crash.
The firetruck from Culver City, California, had stopped in the northbound high occupancy vehicle lane with its emergency lights flashing as it responded to another crash. The firefighters were also uninjured.
The Tesla driver, from suburban Woodland Hills, told the NTSB that he was traveling to work in Los Angeles when the crash happened. He told investigators he was looking forward with his hand rested on his knee while touching the bottom of the steering wheel.
Just before the crash, a large vehicle, an SUV or pickup truck, changed lanes in front of him, the driver told the NTSB.
"Although the driver stated that he was looking forward, he was unable to see the firetruck in time enough to avoid the crash. The driver had coffee and a bagel at the time, but he wasn't sure if either was in his hand when the crash occurred," according to the report.
Cellphone data showed the driver was not using his phone to talk or text in the minutes leading up to the crash.
A statement from a driver in a nearby vehicle provided by Tesla said the driver appeared to be looking down at a cellphone or other device he was holding in his left hand before the crash.
The NTSB determined in September 2017 that design limitations of the Tesla Model S Autopilot played a major role in a May 2016 fatal crash in Florida involving a vehicle operating under Autopilot. But it blamed the crash on an inattentive Tesla driver's overreliance on technology and a truck driver who made a left turn in front of the car.
The California investigation comes as the federal government has few regulations governing autonomous vehicles and driver-assist systems that can drive a car under certain circumstances. The systems can significantly reduce crashes, but computer-driven vehicles also can make mistakes.