Tesla's Autopilot Under Investigation After Fatal Crash

— -- Tesla's autopilot mode is undergoing a preliminary investigation by the U.S. National Highway Traffic Safety Administration, the automaker said today, following a recent crash that killed a driver who was using the semi-autonomous feature.

The Tesla driver was on a divided highway using autopilot when a tractor-trailer drove across the highway perpendicular to the Model S, according to a statement released today by the company.

"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."

Tesla's autopilot radar tunes out things such as overhead road signs in order to avoid "false braking events," Tesla CEO Elon Musk said on Twitter. Neither the Tesla driver nor the autopilot system noticed the white side of the high ride tractor-trailer in the bright sky, the company said.

The automaker said it informed federal authorities as part of its standard procedure following the crash and noted the preliminary investigation is to determine "whether the system worked according to expectations."

When the Tesla autopilot is activated, it reminds drivers to "always keep your hands on the wheel. Be prepared to take over at any time."

"Autopilot is getting better all the time, but it is not perfect and still requires the driver to remain alert," the company's statement said. "Nonetheless, when used in conjunction with driver oversight, the data is unequivocal that Autopilot reduces driver workload and results in a statistically significant improvement in safety when compared to purely manual driving."

The identity of the victim was not immediately known. However, Tesla's statement said the man "was a friend to Tesla and the broader [electric vehicle] community, a person who spent his life focused on innovation and the promise of technology and who believed strongly in Tesla’s mission. We would like to extend our deepest sympathies to his family and friends."

This is the first known fatality in more than 130 million miles driven with autopilot activated, according to Tesla.