Government officials are looking into a fatal accident that involved a Tesla Model S that was operating in semi-autonomous mode.
The National Highway Traffic Safety Administration has opened a preliminary evaluation into the accident; it’s the first “known fatality in just over 130 million miles where Autopilot was activated,” according to Tesla. NHTSA is evaluating the circumstances to determine whether the company’s Autopilot system performed as expected during the accident.
“It is important to emphasize that the NHTSA action is simply a preliminary evaluation to determine whether the system worked according to expectations,” a Tesla spokesperson wrote in a blog post.
The vehicle in question was driving down a divided highway semi-autonomously using Autopilot when a tractor trailer crossed its path. Neither the car’s sensors nor the driver saw the trailer, according to Tesla’s blog post, because the trailer’s white exterior was difficult to detect against the “brightly lit sky.”
“The high ride height of the trailer combined with its positioning across the road and the extremely rare circumstances of the impact caused the Model S to pass under the trailer, with the bottom of the trailer impacting the windshield of the Model S,” the blog post stated.
The company emphasized that the Autopilot technology requires the owner to acknowledge the feature is still being tested and that they’re advised to keep their hands on the wheel and be prepared to take over if the software can’t properly navigate on its own. In situations where the driver remains alert, data shows Autopilot improves driver safety, according to the company.
There is an ongoing debate in the industry over whether rolling out semi-autonomous features incrementally is safe. Opponents say doing so introduces the potential of human error to autonomous technology while proponents argue exposure to semi-autonomous technology is necessary and allows consumers to become more comfortable and fluent with how to use it.
This article originally appeared on Recode.net.