The National Highway Traffic Safety Administration said Thursday that it closed its investigation of a fatal crash involving Tesla’s Autopilot system, finding the technology in the Model S worked as it was designed.

The crash occurred near Williston, Fla., in May 2016 when a Tesla Model S sedan in Autopilot mode, which includes some self-driving features, drove under the trailer of a semi-tractor, killing the car’s driver, Joshua Brown of Ohio. Tesla later wrote in a blog post that “neither Autopilot nor the driver noticed the white side of the tractor trailer against a brightly lit sky, so the brake was not applied.”

Brown had posted video of himself on YouTube using Autopilot without his hands on wheel.

NHTSA said Thursday that the truck, which had made a left turn across the highway the Tesla was traveling on, should have been visible seven seconds before the crash, which the safety agency said should have been enough time for the driver to react.

“While technology is capable of preventing crashes, not all systems can do all things,” NHTSA spokesman Bryan Thomas said on a call with reporters.

With no evidence of a safety-related defect, the auto-safety agency isn’t ordering a recall to fix Tesla vehicles. NHTSA also noted that Tesla on its own rolled out a software update in September that issued more warnings if a driver’s hands weren't on the wheel and shut down the Autosteer function of Autopilot for drivers who repeatedly ignored the warnings.

The NHTSA investigation examined the crash scene as well as data from other incidents provided by Tesla. The agency also compared Tesla’s systems to those available on comparable vehicles. It found that Tesla’s technology was in line with the industry’s state-of-the-art, and that automatic braking for vehicles turning across a highway was “outside the expected performance capabilities.”

The agency also analyzed the crash rates in model year 2014-2016 Tesla Model S and 2016 Model X vehicles and found that the crash rate dropped by almost 40 percent after Autosteer was installed.

But Teslas that have Autosteer also have automatic emergency braking (automatic emergency braking was added in a few months before Autosteer in 2015), which the Insurance Institute for Highway Safety says reduces rear-end crashes by 40 percent. Consumer Reports has follow-up questions into NHTSA about how much of the Tesla crash decline might be attributable to automatic emergency braking.

In addition, the agency looked at the kinds of warnings Tesla includes in its owner's manuals and driver-user interfaces. Although they’re not specific as they could be, the warnings accurately described the systems’ limitations, NHTSA said.

Tesla in a statement said that “the safety of our customers comes first, and we appreciate the thoroughness of NHTSA’s report and its conclusion.”

The Tesla crash caused safety advocates, including Consumer Reports, to question whether the name Autopilot, as well as the marketing hype of its roll-out, promoted a dangerously premature assumption that the Model S was capable of truly driving on its own. Tesla’s own press release for the system announced “Your Autopilot has arrived” and promised to relieve drivers “of the most tedious and potentially dangerous aspects of road travel.” The release also stated that the driver “is still responsible for, and ultimately in control of, the car.”

Consumer Reports believes that these two messages—your vehicle can drive itself, but you may need to take over the controls at a moment’s notice—create potential for driver confusion. It also increases the possibility that drivers using Autopilot may not be engaged enough to to react quickly to emergency situations.

In general, though Consumer Reports supports technology that advances the consumer interest, the independent, nonprofit organization believes in a careful balance of innovation and safety.

NHTSA’s Thomas said the agency was interested in nurturing new safety technologies, and it wanted to encourage innovation even as different automakers experiment with different methods. Eventually, the industry will settle on best practices. In the meantime, the agency will continue to investigate and take action as necessary, he said.