DETROIT — The race by automakers and technology firms to develop self-driving cars has been fueled by the belief that computers can operate a vehicle more safely than human drivers.
But that view is now in question after the revelation on Thursday that the driver of a Tesla Model S electric sedan was killed in an accident when the car was in self-driving mode.
Federal regulators, who are in the early stages of setting guidelines for autonomous vehicles, have opened a formal investigation into the incident, which occurred on May 7 in Williston, Fla.
In a statement, the National Highway Traffic Safety Administration said preliminary reports indicated that the crash occurred when a tractor-trailer made a left turn in front of the Tesla, and the car failed to apply the brakes.
It is the first known fatal accident involving a vehicle being driven by itself by means of sophisticated computer software, sensors, cameras and radar.
The safety agency did not identify the Tesla driver who was killed. But the Florida Highway Patrol identified him as Joshua Brown, 40, of Canton, Ohio.
He was a Navy veteran who owned a technology consulting firm. In a news release, Tesla on Thursday described him as a man “who spent his life focused on innovation and the promise of technology and who believed strongly in Tesla’s mission.”
Mr. Brown posted videos of himself riding in autopilot mode. “The car’s doing it all itself,’’ he said in one, smiling as he took his hands from the steering wheel.
Video by Joshua Brown
In another, he praised the system for saving his car from an accident.
The death is a blow to Tesla at a time when the company is pushing to expand its product lineup from expensive electric vehicles to more mainstream models. The company on Thursday declined to say whether the technology or the driver or either were at fault in the accident.
In its news release it said, “Neither autopilot nor the driver noticed the white side of the tractor-trailer against a brightly lit sky, so the brake was not applied.”
The crash also casts doubt on whether autonomous vehicles in general can consistently make split-second, life-or-death driving decisions on the highway.
And other companies are increasing investments in self-driving technology. Google, for example, recently announced plans to adapt 100 Chrysler minivans for autonomous driving. Earlier this year, G.M. acquired the software firm Cruise Automation to accelerate its own self-driving applications.
Even as the companies conduct many tests on autonomous vehicles at both private facilities and on public highways, there is skepticism that the technology has progressed far enough for the government to approve cars that totally drive themselves.