The Tesla Model 3 that crashed into a tractor-truck on March 1 in Florida had Autopilot engaged at the time of the crash, according to the National Transportation Safety Board's (NTSB) preliminary report.
The Tesla Model 3 was traveling at 68 mph (110 km/h) in a 55 mph zone when it struck the truck's trailer and continued under it, shearing the Tesla's roof off and killing its 50 year-old driver, Jeremy Banner.
According to NTSB investigators, Tesla's advanced driver assistance system (ADAS), Autopilot, was engaged about 10 seconds before impact.
Banner's hands hadn't touched the wheel from less than 8 seconds before the crash, according to vehicle data.
After reviewing vehicle data and surveillance video footage, the NTSB found that neither Autopilot nor the driver attempted to avoid crashing into the truck.
"Neither the preliminary data nor the videos indicate that the driver or the ADAS executed evasive maneuvers," investigators wrote.
Video footage showed that the truck was crossing the highway and had slowed as it crossed the southbound lanes of State Highway 441 in Palm Beach County, blocking the Tesla's path.
The Tesla continued southbound on 441 for about 1,600 feet (500m) after impact.
NTSB continues to investigate the probable cause of the incident with the aim of issuing safety recommendations to prevent similar crashes.
The circumstances leading to the crash share many similarities with the 2016 death of Tesla driver, Joshua Brown, who crashed into the trailer of a truck that was crossing two-lanes on a highway in Florida.
NTSB noted in its final 2017 report into the 2016 crash that the driver was over reliant on Tesla's Autopilot, which was also engaged when it crashed.
Among seven recommendations it made from the investigation was that "Tesla's automated vehicle control system was not designed to, and could not, identify the truck crossing the Tesla's path or recognize the impending crash."
It also said the way Autopilot monitored and responded to driver interaction with the wheel "was not an effective method of ensuring driver engagement". As a result, Tesla shorted the time Autopilot issues a warning alert when the driver's hands are off the wheel.
Autopilot was also engaged when Apple engineer Wei 'Walter' Huang crashed his Model X into a road barrier and died. In April, his family filed a lawsuit against Tesla in a California state court, alleging negligence on the part of the electric car maker.
A Tesla spokesperson told ZDNet in response to the NTSB report: "Shortly following the accident, we informed the National Highway Traffic Safety Administration and the National Transportation Safety Board that the vehicle's logs showed that Autopilot was first engaged by the driver just 10 seconds prior to the accident, and then the driver immediately removed his hands from the wheel. Autopilot had not been used at any other time during that drive. We are deeply saddened by this accident and our thoughts are with everyone affected by this tragedy.
"Tesla drivers have logged more than one billion miles with Autopilot engaged, and our data shows that, when used properly by an attentive driver who is prepared to take control at all times, drivers supported by Autopilot are safer than those operating without assistance. For the past three quarters we have released quarterly safety data directly from our vehicles which demonstrates that."