Photo of Northbound view of the crash scene before the Tesla was engulfed in flames.

​​Northbound view of the crash scene before the Tesla was engulfed in flames. (Source:

witness S. Engleman)

Collision Between a Sport Utility Vehicle Operating With Partial Driving Automation and a Crash Attenuator

What Happened

​​On March 23, 2018, at 9:27 a.m., a 2017 Tesla Model X P100D electric-powered sport utility vehicle (SUV), occupied by a 38-year-old male driver, was traveling south on US Highway 101 (US-101) in Mountain View, Santa Clara County, California. At this location, US-101 has six southbound traffic lanes, including a high-occupancy vehicle (HOV) exit lane to State Route 85 (SR-85) southbound on the far left. As the SUV approached the US-101−SR-85 interchange, it was traveling in the lane second from the left, which was an HOV lane for continued travel on US-101.

While approaching a paved gore area dividing the main travel lanes of US-101 from the SR-85 left-exit ramp, the SUV moved to the left and entered the gore. The vehicle continued traveling through the gore and struck a damaged and nonoperational crash attenuator at a speed of about 71 mph. The crash attenuator was positioned at the end of a concrete median barrier. As a result of the collision, the SUV rotated counterclockwise and the front body structure separated from the rear of the vehicle. The Tesla was involved in subsequent collisions with two other vehicles, a 2010 Mazda 3 and a 2017 Audi A4.

The Tesla’s high-voltage battery was breached in the collision and a postcrash fire ensued. On-scene witnesses found the Tesla driver in his seat with his lap/shoulder belt buckled. They removed him from the vehicle before it was engulfed in flames. The driver was transported to a local hospital, where he died from blunt-force trauma injuries. The driver of the Mazda sustained minor injuries, and the driver of the Audi was uninjured.

System performance data downloaded from the Tesla indicated that the driver was operating the SUV using the Traffic-Aware Cruise Control (an adaptive cruise control system) and Autosteer system (a lane-keeping assist system), which are advanced driver assistance systems in Tesla’s “Autopilot” suite. As part of this investigation, the National Transportation Safety Board (NTSB) reviewed previous NTSB investigations involving the Tesla Autopilot system in Williston, Florida; Culver City, California; and Delray Beach, Florida, to examine common issues regarding the safety of advanced driver assistance systems that provide partial driving automation (both lateral and longitudinal control).

4/12/2018 - Tesla Party Removal Notification Letter to CEO Elon Musk

What We Found

The probable cause of the Mountain View, California, crash was the Tesla Autopilot system steering the sport utility vehicle into a highway gore area due to system limitations, and the driver’s lack of response due to distraction likely from a cell phone game application and overreliance on the Autopilot partial driving automation system. Contributing to the crash was the Tesla vehicle’s ineffective monitoring of driver engagement, which facilitated the driver’s complacency and inattentiveness. Contributing to the severity of the driver’s injuries was the vehicle’s impact with a crash attenuator barrier that was damaged and nonoperational at the time of the collision due to the California Highway Patrol’s failure to report the damage following a previous crash, and systemic problems with the California Department of Transportation’s maintenance division in repairing traffic safety hardware in a timely manner.​

What We Recommended

We made recommendatins to the National Highway Traffic Safety Administration, to the Occupational Safety and Health Administration, to SAE International, to Manufacturers of Portable Electronic Devices (Apple, Google, HTC, Lenovo, LG, Motorola, Nokia, Samsung, and Sony), to Apple Inc.


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